JP4512693B2 - Polarization control element, manufacturing method thereof, and microscope - Google Patents

Description

  The present invention relates to a polarization control element, a manufacturing method thereof, and a microscope.

  Various optical elements are used in optical instruments such as a microscope. Examples of the optical element include a polarizing plate that converts incident light into linearly polarized light and a phase plate that delays the phase of incident light. Such an optical element can change the deflection state of incident light. Further, an optical element obtained by dividing an anisotropic optical element into four parts is disclosed (Non-Patent Document 1). Furthermore, an optical element using a photonic crystal is disclosed (Patent Document 1, Non-Patent Document 2).

The polarizing plate has a polarization axis in a predetermined direction, and controls so that light becomes linearly polarized light. That is, the polarizing plate emits light as linearly polarized light in a direction along the optical axis. Therefore, when natural light (non-polarized light) is incident, the light is emitted as linearly polarized light. In addition, the wave plate causes a predetermined phase difference between the O light and the E light. For example, a half-wave plate causes a phase difference of 180 °. In addition, the quarter wavelength plate causes a phase difference of 90 °. Therefore, in the half-wave plate, when the angle formed by the optical axis of the wave plate and the direction of the linearly polarized light is 45 °, the direction of the linearly polarized light is rotated by 90 ° and emitted. In the quarter wave plate, when the angle formed by the optical axis of the wave plate and the direction of the linearly polarized light is 45 °, the light is emitted from the linearly polarized light as circularly polarized light.
JP-A-10-335758 R. Dorn, S .; Quabis, and G.G. Leuchs, Phys. Rev, Lett. 91,233901 (2003) Photonic Lattice Website Products & Applications Optical Elements Photonic Crystal Composite Optical Elements [Search January 5, 2006], Internet <URL: http://www.photonic-lattice.com/index.html>

  By the way, in the second harmonic microscope (SHG: Second Harmonic Generation), a laser fluorescence microscope for detecting molecular orientation, a Raman microscope, a near-field microscope, etc., the z component of the focused electric field can be increased or decreased. It is desired. As shown in FIG. 12A, it is desired to generate radial polarized light whose polarization axis is radial, or azimuth polarized light in which linearly polarized light is distributed in a direction orthogonal to the radial polarized light. In radial polarization and azimuth polarization, Ex and Ey have distributions of x and y. In the radial polarization, as shown in FIG. 12A, linearly polarized light is distributed along a radial direction from one central point. In azimuth polarized light, as shown in FIG. 12B, linearly polarized light is distributed in a direction orthogonal to radial polarized light. Thus, there is a demand for an optical element that forms a polarization state in which the vibration direction of the electric vector of light has a spatial distribution in the light beam cross section.

  When a light beam in a radial polarization state is collected by, for example, an objective lens and irradiated on the sample, the z component of the electric vector of light increases on the sample. On the other hand, when the azimuth polarized light is condensed by the objective lens and irradiated on the sample, the z component of the electric vector of light becomes small on the sample. Therefore, an optical element that generates a radial polarization state or an azimuth polarization state is expected to be used for various applications. However, such an optical element has a problem that its manufacturing method has not been established and it cannot be manufactured with high productivity.

  The present invention has been made against the background of such circumstances, and an object of the present invention is to use a polarization control element capable of bringing light into a predetermined polarization state, a method for manufacturing the same, and the polarization control element. Is to provide a microscope.

  The polarization control element according to the first aspect of the present invention is a polarization control element that changes the polarization state of incident light in accordance with the incident position, and is a divided region that is radially divided into eight or more, and the incident light. In this example, there are divided regions each provided with a wavelength plate that emits light with a phase shifted, and the optical axes of a pair of wavelength plates provided in the opposite divided regions are substantially orthogonal to each other. Thereby, pseudo radial polarization or pseudo azimuth polarization can be easily realized.

  The polarization control element according to the second aspect of the present invention is the polarization control element described above, wherein the wavelength plate has a photonic crystal formed on the substrate. Thereby, it is possible to prevent the polarization state from being disturbed at the boundary between the divided regions.

  A polarization control element according to a third aspect of the present invention is characterized in that, in the above-described polarization control element, the divided region is formed by attaching a radially divided wave plate to a substrate. It is. With a simple configuration, pseudo radial polarization or pseudo azimuth polarization can be easily realized.

  A polarization control element according to a fourth aspect of the present invention is the polarization control element described above, wherein the 16 divided regions are provided. Thereby, it can be set as the polarization state closer to radial polarization or azimuth polarization.

  A polarization control element according to a fifth aspect of the present invention is characterized in that an identification mark for identifying the optical axis of the wave plate is provided in the polarization control element described above. Thereby, when arrange | positioning the polarization control element 100, an angle can be adjusted simply.

  A laser microscope according to a sixth aspect of the present invention includes a polarization control element, a light source that emits light incident on the polarization control element, and a light that is collected from the polarization control element. And an objective lens for irradiating the lens. Thereby, z component of an electric vector can be made high or z component can be made low, and the application field of a laser microscope can be expanded.

  A method for manufacturing a polarization control element according to a seventh aspect of the present invention is a method for manufacturing a polarization control element that changes a polarization state of incident light in accordance with an incident position, and is divided into two or more radially on a substrate. A groove pattern in a predetermined direction is formed for each divided region, a photonic crystal having a periodic structure of a plurality of dielectric films is formed on a substrate provided with the groove pattern, and an optical element is formed on the opposed divided regions. A wave plate whose axes are substantially orthogonal is formed. Thereby, the polarization control element which can implement | achieve pseudo radial polarization or pseudo azimuth polarization by a simple method can be manufactured.

  A method for manufacturing a polarization control element according to an eighth aspect of the present invention is a method for manufacturing a polarization control element that changes the polarization state of incident light according to an incident position, and an optical axis is provided in a predetermined direction. A plurality of wave plates are prepared, and each of the wave plates is radially divided so that an angle formed by the optical axis and the cutting line is different for each of the wave plates, and two or more from each wave plate A polarization control element that changes the polarization state of incident light according to an incident position, wherein a predetermined number of divided areas are formed from the plurality of divided areas formed from the plurality of wavelength plates. A region is selected, and among the plurality of wave plates, a divided region selected from the first wave plate is attached to the substrate, and the plurality of wavelengths are adjacent to the divided region selected from the first wave plate. Of the plates selected from other wave plates Paste regions, on opposite divided region, in which the optical axis of the wavelength plate is arranged perpendicular. Thereby, the polarization control element which can implement | achieve pseudo radial polarization or pseudo azimuth polarization by a simple method can be manufactured.

  A polarization control element manufacturing method according to a ninth aspect of the present invention is the above-described manufacturing method, wherein, among the divided regions divided from the first wave plate, other divided regions that are not bonded to the substrate are used. Of the divided regions that are bonded to the substrate and divided from the second wave plate, the divided regions that are not bonded to the substrate are arranged next to the divided region that is divided from the first wave plate. In this way, it is bonded to the other substrate. Thereby, material cost can be reduced and it can manufacture with high productivity.

  ADVANTAGE OF THE INVENTION According to this invention, the polarization control element which can be set as a predetermined polarization state, its manufacturing method, and a microscope can be provided.

  Hereinafter, embodiments to which the present invention can be applied will be described. The following description is to describe the embodiment of the present invention, and the present invention is not limited to the following embodiment. For clarity of explanation, the following description is omitted and simplified as appropriate. Further, those skilled in the art will be able to easily change, add, and convert each element of the following embodiments within the scope of the present invention. In addition, what attached | subjected the same code | symbol in each figure has shown the same element, and abbreviate | omits description suitably.

Embodiment 1 of the Invention
A polarization control element according to an embodiment of the present invention will be described with reference to FIG. Fig.1 (a) is a front view which shows typically the structure of the polarization control element concerning this Embodiment. FIG.1 (b) is a side view which shows the structure of the polarization control element concerning this Embodiment. Here, the polarization control element 100 divided into eight will be described as an example of the polarization control element according to the present invention. Further, the surface on which the plate-like polarization control element 100 is arranged is an XY plane as shown in FIG. Further, as shown in FIG. 1B, the direction perpendicular to the polarization control element 100 is taken as the Z direction. Therefore, the light beam that passes through the polarization control element 100 usually propagates along the Z direction.

  The polarization control element 100 has a transparent substrate 50 made of glass or the like. The substrate 50 has eight regions divided radially. As shown in FIG. 1, these eight areas are defined as a divided area 51 to a divided area 58. That is, the polarization control element 100 includes eight divided regions 51 to 58. The divided areas 51 to 58 are divided symmetrically with respect to the center point. Therefore, the eight polarization control elements 100 are arranged radially. In this way, the eight regions divided radially are divided regions 51 to 58. The size of each divided area is equal. The divided areas 51 to 58 are provided over the entire circumferential direction. Accordingly, each of the divided regions 51 to 58 is an isosceles triangle having an internal angle of 45 ° corresponding to a point near the center point. The combined shape of the divided areas 51 to 58 is a regular octagon. In other words, triangles obtained by dividing a regular octagon into eight equal parts are divided areas 51 to 58. Note that the center point of the divided region may not be the center of the substrate 50. That is, the center of the substrate 50 and the center of the divided region do not have to coincide with each other.

  Each of the divided regions 51 to 58 is provided with a half-wave plate having optical axes in different directions. That is, the vibration direction of light is different for each of the divided areas 51 to 58. In FIG. 1A, the optical axes in the divided areas 51 to 58 are indicated by arrows. Here, the optical axis of each divided region is shifted by 22.5 ° from the optical axis of the adjacent divided region. That is, with reference to the direction of the Y-axis, as shown in FIG. 1, the angle of the optical axis of the wave plate in the divided region 51 is 0 °, the optical axis of the divided region 52 is −22.5 °, and the divided region The optical axis of 52 is −45 °, and the optical axis of the divided region 54 is −67.5 °. The optical axis of the divided area 58 is 22.5 °, the optical axis of the divided area 57 is 45 °, the optical axis of the divided area 56 is 67.5 °, and the optical axis of the divided area 55 is 90 °. It becomes.

  Accordingly, the optical axes of the pair of wave plates provided in the divided regions facing each other with respect to the center point are orthogonal to each other. For example, the optical axis of the divided area 51 is 0 °, and the optical axis of the divided area 55 facing the divided area 51 is 90 °. The optical axis of the divided area 52 and the optical axis of the divided area 56 are orthogonal to each other. Similarly, the divided regions 53 and 57 have orthogonal optical axes, and the divided regions 54 and 58 have orthogonal optical axes. In other words, the angle difference between the optical axes of the pair of wave plates provided in the divided regions facing each other is 90 °. As described above, the pair of divided regions arranged diagonally across the center point of the divided regions 51 to 58 are provided with wave plates having different optical axes by 90 °.

  The half-wave plate emits incident light with a half-wave phase difference. Therefore, if the angle formed by the direction of the linearly polarized light with respect to the optical axis of the half-wave plate is θ, the light passing through the half-wave plate is the linearly polarized light rotated by 2θ from the original linearly polarized light. Become. For example, when the optical axis of the half-wave plate and the polarization axis of linearly polarized light are shifted by 45 °, the half-wave plate emits linearly polarized light whose polarization axis is shifted by 90 °. The wavelength plate is provided on the front surface 50 a of the substrate 50. Moreover, it is preferable to apply AR coating to the back surface 50b in order to prevent reflection.

  A polarization state of light emitted from the polarization control element 100 shown in FIG. 1 will be described with reference to FIG. FIG. 2 shows a case where linearly polarized light having a polarization axis along the Y direction is incident. Therefore, the polarization azimuth of the outgoing light that is emitted when linearly polarized light having an incident polarization azimuth of 0 ° is described. That is, the case where the optical axis of the divided region 51 and the polarization axis of the incident light coincide with each other will be described. In FIG. 2, the polarization axes of the emitted light emitted from each divided region are indicated by arrows. The polarization axes of the linearly polarized light emitted from the divided areas 51 to 58 are radial. In FIG. 2, the substrate 50 is not shown.

  Specifically, the polarization axes of linearly polarized light emitted from a pair of divided regions facing the center point are parallel. And a vibration direction is opposite in a pair of division area which opposes. Further, the polarization axis of the light emitted from the adjacent divided regions is shifted by 45 °. For example, the polarization axis of the light emitted from the divided area 51 and the divided area 55 is 0 °. Further, the polarization axis of the light emitted from the divided region 52 and the divided region 56 is −45 °, and the polarization axis of the light emitted from the divided region 53 and the divided region 57 is 90 °. The polarization axis of the light emitted from the divided region 58 is + 45 °. Therefore, the angle of the polarization axis changes according to the incident position, and the outgoing polarization displacement becomes radial. As described above, the polarization control element 100 according to the present embodiment controls the polarization state of incident light to change to a desired polarization state according to the incident position.

  By making linearly polarized light incident on the polarization control element 100, it is possible to control the polarization state to be close to radial polarization. That is, the linearly polarized light can be changed to pseudo radial polarized light that approximates radial polarized light. Further, when linearly polarized light whose polarization axis is in the X direction is incident on the polarization control element 100, the polarization axis has a shape close to a circle. Therefore, a polarization state close to azimuth polarization can be obtained. That is, pseudo azimuth polarized light approximate to azimuth polarized light can be obtained. The distribution of the polarization axes in the xy plane at this time is as shown in FIG.

  By increasing the number of divisions of the polarization control element 100, a polarization state closer to radial polarization or azimuth polarization can be achieved. In other words, increasing the number of divided regions changes the polarization axis more smoothly. In other words, when the number of divisions is infinite, an ideal radial polarization state as shown in FIG. 12A or an ideal azimuth polarization state as shown in FIG. 12B can be generated. The number of divisions is preferably an even number, and can be, for example, 2 or 4 or more. Furthermore, in order to increase the z component of the electric field vector, the number of divisions is preferably 8 or more, and more preferably 16 or more. That is, the number of divisions is preferably 2n (n is an integer of 1 or more). Moreover, it is preferable to divide symmetrically with respect to the center point of a divided area and to make the size of the opposed divided areas the same. In other words, it is preferable that the central angles of the divided areas are equal to each other so that the divided areas have the same size. For example, if the number of divisions is 2n, the angle corresponding to one divided region is 360 degrees / 2n.

  Specifically, for example, when the number of divisions is 16, the optical axis of the wave plate is shifted by 11.25 ° from the adjacent division region. As a result, the optical axes are orthogonal to each other in the divided areas facing each other. When a polarization axis having a certain angle is incident on the polarization control element, linearly polarized light is emitted as pseudo radial polarized light or pseudo azimuth polarized light.

In the arbitrary cross section (z = z ₁ ) of the light beam, the x component and the y component of the electric vector in the radial polarization state are expressed as follows.
Ex = x / (x ² + y ² ) · A · sin (kz ₁ -wt-c)
Ey = y / (x ² + y ² ) · A · sin (kz ₁ -wt-c)
Further, the x component and the y component of the electric vector in the azimuth polarization state are shown as follows.
Ex = x / (x ² + y ² ) · A · sin (kz ₁ -wt-c)
Ey = y / (x ² + y ² ) · A · sin (kz ₁ -wt-c)
However, one point on the beam cross section is defined as the origin (x = 0, y = 0). Here, w is the frequency of light, k is the wave number, t is time, and c is an arbitrary constant.

With regard to pseudo radial polarization and pseudo azimuth polarization, in the case of 2n equal parts, the direction of the optical axis in each divided region can be defined as follows. However, in the following formula, the polarization axis of incident linearly polarized light is set to 0 °.
Optical axis 90 ° / n × i (i = 0, 1, 2, 3,..., N−1) of the half-wave plate in the case of generating pseudo radial polarization
Optical axis 90 ° / n × i + 45 ° of a half-wave plate in the case of generating pseudo azimuth polarized light with respect to linearly polarized light (i = 0, 1, 2, 3,..., N−1)

  As shown in FIG. 1, the polarization control element 100 is provided with an identification mark 59 for identifying the direction of the optical axis in the wave plate. The identification mark 59 is provided on the divided area 51. That is, it is provided outside the divided area 51. Therefore, the optical axis of the divided region 51 corresponding to the identification mark 59 can be easily determined. Thereby, when arrange | positioning the polarization control element 100, an angle can be adjusted simply.

  The above-described polarization control element 100 can be manufactured, for example, by forming a photonic crystal on the substrate 50. Thereby, the wavelength plate which has a different optical axis in the division area 51-the division area 58 can be provided. Specifically, the surface 50a on the front side of the substrate 50 is a growth surface of the photonic crystal. The optical axes of the wavelength plates of the divided regions 51 to 58 can be set according to the direction of the photonic crystal. A photonic crystal is a structure in which a plurality of dielectrics are alternately stacked with a period of about the wavelength of light. For example, the photonic crystal can be formed by a manufacturing method disclosed in Japanese Patent Application Laid-Open No. 10-335758. it can. Specifically, an etching process is performed on a transparent substrate 50 such as glass to form a predetermined pattern groove. The pattern grooves are periodically formed with a predetermined width on the substrate. The pattern groove is formed in a direction corresponding to the optical axis of each divided region. For example, the pattern grooves are formed in the orthogonal direction in the opposed divided regions. In addition, the direction of the divided region and the pattern groove is shifted adjacently. Therefore, the pattern grooves are formed in different directions for each divided region. As the etching process, for example, an ion beam etching process can be used. Thereby, the pattern groove | channel for forming a photonic crystal can be formed accurately.

Then, a plurality of dielectrics having different refractive indexes are alternately stacked on the pattern groove. As these dielectrics, for example, a low refractive material SiO ₂ and a high refractive material Si can be used. Further, Ta ₂ O ₅ can be used as the high refractive material. These dielectric films are formed by bias sputtering, for example. Thereby, sputter etching is performed at the time of film formation and at that time, and a desired periodic structure can be obtained. That is, it is preferable to form a photonic crystal by a self-cloning method. The self-cloning method is a method in which a plurality of materials are periodically formed in advance by a combination of sputter film formation and sputter etching on a substrate on which an uneven pattern (groove pattern) is formed. As a result, a steady structure with a certain unevenness is generated, and a multilayer film is formed while being accurately transmitted from the lower film to the upper film. The film forming conditions can be, for example, those described in JP-A-10-335758. The dielectric films are alternately stacked with a period of about the wavelength of incident light. Thereby, the photonic crystal grows along the direction of the groove pattern. Therefore, a desired three-dimensional structure can be obtained, and the optical axis of the wave plate can be set in a desired direction. In this way, a wave plate having a desired optical axis can be easily formed. The polarization state can be controlled by changing the direction of the pattern groove for each divided region. That is, it can be controlled so as to have different polarization states according to the incident position of the incident light.

  By forming a photonic crystal by the self-cloning method, the accuracy is improved and the influence of diffracted light or the like can be reduced. That is, by forming a wave plate using a photonic crystal, the polarization state is not disturbed even in the vicinity of the boundary of the divided regions. Therefore, a polarization state closer to azimuth polarization or radial polarization can be generated. In this embodiment, a photonic crystal is formed on a substrate, and a wavelength plate is provided on the substrate. Therefore, a polarization control element capable of generating a desired polarization state can be manufactured by a simple method. Thereby, a polarization control element can be manufactured with high productivity.

  The identification mark 59 can be formed by, for example, an etching process. Further, the identification mark 59 is preferably formed by an etching process when forming the pattern groove. This eliminates the need for a separate step for forming the identification mark 59, so that the identification mark 59 can be easily formed. Of course, the identification mark may be formed by a method other than the etching process. Thereby, the direction of the optical axis of the wave plate can be easily identified. Further, the identification mark may be formed by notching or marking a part of the substrate 50.

  As a specific example, a substrate 50 having a side of 15 mm and a thickness of 0.5 mm can be used. As the substrate 50, a transparent glass substrate can be used. Further, the combined area of the divided areas 51 to 58 can be 12 mm in the X direction and the Y direction. In this case, the effective beam diameter is 10 mm. That is, it is possible to generate a pseudo-azimuth polarized light beam or a pseudo radial polarized light beam with a spot diameter of 10 mm. This effective diameter can be, for example, about the pupil diameter of an objective lens in a microscope. When the beam diameter is 1 mm, laser light having an average power of 2 W can be irradiated.

Embodiment 2 of the Invention
The polarization control element according to the present embodiment includes four divided regions. These four divided areas are divided radially as in the first embodiment. The optical axes of the pair of wave plates provided in the opposing regions are orthogonal to each other. Thereby, the effect similar to Embodiment 1 can be acquired. Note that the description of the same configuration as that of Embodiment 1 is omitted. However, the polarization control element according to the present embodiment is manufactured by a method different from that of the first embodiment. That is, although the wavelength plate is formed using the photonic crystal in the first embodiment, in this embodiment, the wavelength plate is divided into a plurality of divided regions. The polarization control element is formed by attaching the divided region to the substrate.

  A manufacturing process of the polarization control element according to the present embodiment will be described with reference to FIGS. FIG. 4 is a front view showing a manufacturing process of the polarization control element according to this embodiment. First, as shown in FIG. 4A, two wave plates 60 and 70 are prepared. In addition, in order to form two polarization control elements, two substrates 80 and 81 are prepared as shown in FIG. The two wave plates 60 and 70 are normal half-wave plates and rotate the polarization axis of linearly polarized light by 90 °. The two wave plates 60 and 70 are each provided with an orientation flat. That is, a notch is provided in a part of the disc-shaped wave plate. Here, as shown in FIG. 4A, the first wave plate is the wave plate 60 and the second wave plate is the wave plate 70. The optical axes of the wave plates 60 and 70 are indicated by arrows in FIG. The optical axis of the wave plate 60 is orthogonal to the direction of the notch that becomes the orientation flat. On the other hand, the optical axis of the wave plate 70 is inclined 45 ° from the direction of the notch. The wave plates 60 and 70 may be zero order or multi-order.

  The prepared wave plates 60 and 70 are divided into four along the cutting line indicated by the dotted line in FIG. As a result, the wave plates 60 and 70 are cut along the cutting line, and are radially divided into four equal parts. The cutting lines pass through the center of the circle and are orthogonal to each other. Accordingly, a sector-shaped divided region having a central angle of 90 ° is generated. As shown in FIG. 4A, regions where the wave plate 60 is divided are divided regions 61 to 64, and regions where the wave plate 70 is divided are divided regions 71 to 74. At this time, the optical axes of the divided regions 61 to 64 are parallel to one of the cutting lines and perpendicular to the other. On the other hand, the optical axes of the divided regions 71 to 74 are inclined 45 ° from the two cutting lines. The cutting line of the wave plate 60 is arranged so as to cross the orientation flat, and the cutting line of the wave plate 70 is arranged outside the orientation flat so as not to cross the orientation flat.

  By using the two wave plates 60 and 70, two polarization control elements can be manufactured. Specifically, as shown in FIG. 4B, the two divided regions 61 and 62 of the wave plate 60 and the two divided regions 72 and 73 of the wave plate 70 are bonded on the substrate 80, and the first sheet A polarization control element can be formed. Also, the two polarization regions 63 and 64 of the wave plate 60 and the two division regions 71 and 74 of the wave plate 70 can be bonded to the substrate 81 to form a second polarization control element.

  Specifically, the divided regions 61 and 62 are bonded on the substrate 80. On the substrate 80, the divided regions 61 and the divided regions 62 that are arranged adjacent to each other on the wave plate 60 are arranged diagonally. Thereby, the optical axes of the pair of wave plates provided in the divided region 61 and the divided region 62 facing the center are orthogonal to each other. Then, the divided areas 72 and 73 are bonded to the substrate 80, and the divided areas 72 and 73 are arranged between the divided areas 61 and 62 on the substrate 80. Thereby, the optical axes of the pair of wave plates provided in the divided region 72 and the divided region 73 facing the center are orthogonal to each other. Further, the divided areas divided from the wave plate 60 and the divided areas divided from the wave plate 70 are alternately arranged in the circumferential direction. That is, in the circumferential direction, the divided area 61, the divided area 72, the divided area 62, and the divided area 73 are arranged in this order.

  Similarly, the divided regions 63 and 64 are bonded onto the substrate 81. Here, the divided region 63 and the divided region 64 that are arranged adjacent to each other in the wave plate 60 are arranged diagonally. Thereby, the optical axes of the pair of wave plates provided in the divided region 63 and the divided region 64 facing the center are orthogonal to each other. Then, the divided areas 71 and 74 are bonded to the substrate 81, and the divided areas 72 and 73 are disposed between the divided areas 63 and 64 on the substrate 81. Thereby, the optical axes of the pair of wave plates provided in the divided region 72 and the divided region 73 facing the center are orthogonal to each other. Further, the divided areas divided from the wave plate 60 and the divided areas divided from the wave plate 70 are alternately arranged in the circumferential direction. That is, in the circumferential direction, the divided area 63, the divided area 74, the divided area 63, and the divided area 71 are arranged in this order. Thereby, two polarization control elements can be manufactured from two wave plates, and productivity can be improved.

  For bonding the substrates 80 and 81 to the respective divided regions, for example, a resin adhesive can be used. Specifically, an adhesive is provided in the vicinity of the arc portion of the divided region and brought into contact with the substrate 50. Then, the adhesive is cured. At this time, it is desirable that the adhesive does not enter the optically used portion. This can prevent the polarization state from being disturbed. Note that when the transmitted wavefront accuracy can be maintained, an adhesive may be provided on the entire divided region.

  In this way, a plurality of wave plates 60 and 70 having optical axes provided in a predetermined direction are prepared, and the wave plates 60 and 70 are cut radially. At this time, the plurality of wave plates 60 and 70 are divided so that divided regions having the same shape are formed. That is, it is preferable to prepare the wave plates 60 and 70 having the same size and equally divide them radially at the same angle. At this time, the angle formed by the optical axis and the cutting line is changed for each wave plate. In other words, the wave plate is divided on the radiation so that the angle formed by the optical axis of the wave plate and the cutting line differs depending on the wavelength. As a result, a plurality of divided regions are formed from the respective wave plates 60 and 70. The number of divisions of the wave plate may be two or more. In this manner, eight divided regions are formed from the two wave plates 60 and 70.

  Then, a partial region of the eight divided regions generated from the wave plates 60 and 70 is selected. Thereby, a predetermined number of divided regions are selected. Here, four of a divided area 61, a divided area 62, a divided area 72, and a divided area 73 are selected. That is, as many divided regions as the number formed over the entire circumferential direction are selected from among all the divided regions generated by the plurality of wave plates. The divided areas 61 and 62 selected from the divided areas 61 to 64 generated by the first wave plate 60 are bonded onto the substrate 80. At this time, adjacent regions in the circumferential direction are opened so that the divided regions 61 and 62 generated by the first wave plate 60 are not continuously arranged. The divided regions 61 and 62 divided from the first wave plate 60 are preferably arranged diagonally. That is, the adjacent divided regions 61 and 62 in the wave plate 60 are spaced apart and arranged diagonally on the substrate 80.

  The divided areas 72 and 73 selected from the divided areas 71 to 74 generated by the second wave plate 70 are attached to the substrate. Here, the divided areas 72 and 73 selected from the second wave plate 70 are arranged next to the divided areas 61 and 62. That is, the divided regions 72 and 73 are arranged from the second wave plate 70 so as to be adjacent to the divided regions 61 and 62 generated by the first wave plate 60 in the circumferential direction. Thus, the divided regions 72 and 73 divided from the second wave plate 70 are arranged between the divided regions 61 and 62 divided from the first wave plate 60 in the circumferential direction. The The adjacent divided regions are arranged with different optical axis directions. At this time, the adjacent divided regions 71 and 72 in the wave plate 70 are arranged diagonally apart on the substrate 80. Thereby, it arrange | positions so that the optical axis of the division area which opposes on both sides of a center may orthogonally cross. That is, the optical axis of the wave plate is orthogonal in the divided region 61 and the divided region 62. Further, in the divided region 72 and the divided region 73, the optical axes of the wave plates are orthogonal. In addition, the optical axis is inclined 45 ° in the divided region 61 and the divided region 72.

  Further, the remaining divided regions 63 and 64 of the first wave plate 60 are bonded onto the other substrate 81. That is, among the divided areas 61 to 64 divided from the first wave plate 60, the divided areas 63 and 64 that are not bonded to the substrate 80 are bonded to the substrate 81. At this time, like the substrate 80, the divided regions 63 and the divided regions 64 are spaced apart and arranged diagonally. Accordingly, the pair of optical axes provided in the opposed divided regions 63 and 64 are orthogonal to each other. Further, the remaining divided regions 71 and 74 of the second wave plate 70 are bonded to the substrate 81. That is, of the divided areas 71 to 74 divided from the first wave plate 70, the divided areas 71 and 74 that are not bonded to the substrate 80 are bonded to the substrate 81. At this time, the divided areas 71 and 74 are respectively disposed between the divided areas 63 and 64 provided diagonally. Accordingly, in the circumferential direction, the divided regions 71 and 74 divided from the second wave plate 70 are arranged between the divided region 63 and the divided region 64 divided from the first wave plate 60. . In other words, in the circumferential direction, the divided areas divided from the first wave plate 60 and the divided areas divided from the second wave plate 70 are alternately arranged one by one.

  In this way, the second divided polarization control element is produced by pasting the remaining divided regions that are not pasted together when the first polarization control element is formed on another substrate 81. Therefore, material costs can be reduced and productivity can be improved.

  Note that the order of pasting the divided regions is not limited. For example, the divided regions may be bonded together in the order in which they are arranged in the circumferential direction. At this time, the divided region of the first wave plate 60 and the divided region of the second wave plate 70 are alternately bonded. Thereby, bonding accuracy can be improved. Of course, the invention is not limited to the case where two polarization control elements are formed from two wave plates, and a plurality of polarization control elements can be formed from a plurality of wave plates. In the present embodiment, the number of divisions is not limited to four. For example, the number of divisions can be 2 or more. Of course, in order to approach the ideal azimuth polarization state or the ideal radial polarization state, it is preferable to increase the number of divisions, and it is preferable to set the number of divisions to 8 or more.

  The number of wave plates prepared for manufacturing the polarization control element is not limited to two. For example, in the case of four divisions, four polarization control elements can be manufactured by selecting and pasting divided regions one by one from four wave plates. That is, a plurality of divided regions are selected from the divided regions formed by cutting the plurality of wave plates. At this time, one or more divided regions are selected from each wave plate. Then, the plurality of selected divided regions are attached to the substrate. At this time, the divided areas selected from the divided areas of the first wave plate and the divided areas selected from the divided areas of the other wave plates are arranged so as to be adjacent in the circumferential direction. Then, the selected predetermined number of divided regions are pasted so that the entire circumferential direction is filled. In order to form the next polarization control element, a part or all of the divided areas are selected from the remaining divided areas. And it affixes on a board | substrate similarly. By repeating this, the same number of polarization control elements as the number of wave plates can be formed. Therefore, material costs can be reduced and productivity can be improved. Of course, when bonding, the optical plates of the wave plates provided in the opposed divided regions are arranged so as to be orthogonal.

  Next, a configuration of a microscope using the polarization control element according to the present embodiment will be described with reference to FIG. In this embodiment, a polarization control element is used in the second harmonic microscope shown in FIG. A second harmonic generation (SHG) microscope will be described with reference to FIG. FIG. 5 is a configuration diagram showing an outline of the SHG microscope in the present embodiment. The SHG microscope is an optical microscope that uses light of a predetermined wavelength to enter a sample and uses second harmonic generation (SHG). The SHG microscope can be used for observing various samples such as catalytic reaction surfaces, metal and semiconductor microstructures, etc., especially in the fields of medical and biotechnology, etc. It is an effective means. The image of the SHG light intensity represents the molecular orientation distribution and the like, and the orientation distribution pattern can be observed from the molecular concentration due to the non-equilibrium phenomenon. A biological sample is composed of asymmetric biomolecules, and the SHG image is effective for extracting and observing the distribution of special structures in the biological body. In many cases, multiphoton excited fluorescence is generated from the sample along with second harmonic emission. The SHG microscope 1 of this embodiment can simultaneously observe the multiphoton excitation fluorescence together with the second harmonic generated by the sample. Multiphoton excitation fluorescence is excitation fluorescence due to simultaneous absorption of two or more photons.

  In FIG. 5, 10 is a laser light source, 11 is a beam expander, 13 is a beam splitter, 14 is a galvanometer mirror, 15 is a galvanometer mirror, 16 is an objective lens arranged on the incident side, and 17 is an objective lens arranged on the transmission side. A lens, 18 is a photodetector for detecting the second harmonic propagating in the same direction as the incident light, 19 is a photodetector propagating in the opposite direction to the incident light, 20 is a lens, and 21 is a fundamental wave on the transmission side. The cut filter, 22 is a reflection-side fundamental wave cut filter, and 30 is a sample. Reference numeral 100 denotes the polarization control element shown in FIG.

  In the SHG microscope having the configuration shown in FIG. 5, the second harmonic generated in the sample 30 and propagated forward is detected by the photodetector 18, and the second harmonic generated in the sample 30 and propagated backward is detected by the photodetector. 19 is detected. Here, the front is the same direction as the propagation direction of the incident light, and the rear is the direction opposite to the propagation direction of the incident light. The polarization control element 100 may be provided so as to be inserted on the optical path. Then, the second harmonic wave propagating backward is detected with the polarization control element 100 inserted, and the second harmonic wave propagating forward is detected with the polarization control element 100 removed from the optical path. Good.

  As the laser light source 10 of this embodiment, a laser device capable of generating second harmonics and multiphoton fluorescence is used. For example, an infrared light pulse using a mode lock, titanium, sapphire, or a laser can be used for observation of biological cells. As the characteristics of the laser beam such as the laser beam wavelength, the laser beam intensity, the oscillation mode, the repetition frequency, and the pulse width, an appropriate one is selected depending on the sample and the observation method.

  The beam expander 11 expands the beam diameter of the light from the laser light source 10 and emits it. The light beam expanded by the beam expander 11 enters the polarization control element 100. When detecting the second harmonic generated in the sample 30 and propagating backward, the polarization control element 100 is arranged on the optical path. Thereby, pseudo radial polarization can be generated. When detecting the second harmonic generated in the sample 30 and propagating forward, the polarization control element 100 is removed from the optical path. In this case, linearly polarized light is obtained. This polarization control element 100 is the one shown in FIG. The light emitted from the polarization control element 100 is refracted by the lenses 20 a and 20 b and enters the beam splitter 13. Part of the light incident on the beam splitter 13 passes through the beam splitter 13 as it is and enters the galvanometer mirror 14.

  The light reflected by the galvanometer mirror 14 is refracted by the lenses 20 c and 20 d and enters the galvanometer mirror 15. The galvanometer mirror 14 and the galvanometer mirror 15 scan the beam to enable observation and imaging of the entire surface of the sample. The light reflected by the galvanometer mirror 15 is refracted by the lenses 20e and 20f and enters the objective lens 16 on the incident side. The objective lens 16 collects the incident laser light and makes it incident on the sample 30.

  The sample 30 emits a second harmonic having a frequency twice that of the incident light and multiphoton excitation fluorescence by the incident light. A typical multiphoton excited fluorescence is two-photon excited fluorescence. Of the second harmonic and multiphoton excitation fluorescence emitted from the sample 30 and propagating forward, the transmitted light transmitted through the sample 30 is collected by the objective lens 17 on the transmission side. Further, the fundamental wave that has passed through the sample 30 as it is is condensed by the objective lens 17 on the transmission side. The transmission-side objective lens 17 is disposed on the side opposite to the incident-side objective lens 16 with respect to the sample 30. The sample 30 is preferably disposed between the entrance-side objective lens 16 and the transmission-side objective lens 17, and the focal points of the two objective lenses are preferably substantially coincident on the sample.

  The light from the objective lens 17 is refracted by the lenses 20 g and 20 h and enters the fundamental wave cut filter 21. The fundamental wave cut filter 21 separates the second harmonic from the fundamental wave and the multiphoton excitation fluorescence. That is, only the second harmonic wave passes through the fundamental wave cut filter 21 from the light incident on the fundamental wave cut filter 21 from the objective lens 17. The fundamental wave cut filter 21 can be configured by, for example, a band-pass filter or a low-pass filter that blocks the wavelength range of the output light of the laser light source 10 and the wavelength range of multiphoton excitation fluorescence. Alternatively, it may be a dichroic mirror arranged to be inclined with respect to the optical axis. Multi-photon excitation fluorescence can be detected by changing the fundamental wave cut filter 21 to a band-pass filter or the like that cuts off the second harmonic waveband and the fundamental waveband.

  The second harmonic wave that has passed through the fundamental wave cut filter 21 enters the photodetector 18. The light incident on the photodetector 18 is collected by the lens 20 h or the like and is incident on the light receiving surface of the photodetector 18. The photodetector 18 is, for example, a two-dimensional photosensor such as a CCD camera. In order to effectively detect the second harmonic, which is weak light, the photodetector 18 is preferably provided with an image intifier. The photodetector 18 detects incident light and converts it into a video signal. The video signal is input to an image processing apparatus (not shown) that performs image processing, and the captured image is displayed on the display.

  On the other hand, among the second harmonics generated from the sample 30, the second harmonic radiated in the direction opposite to the propagation direction of the incident light propagates in the direction opposite to the incident light. That is, the second harmonic radiated backward is incident on the objective lens 16 again and travels in the direction of the laser light source 10. The second harmonic is refracted by the objective lens 16, the lens 20 f and the lens 20 e and enters the galvanometer mirror 15. The second harmonic wave reflected by the galvanometer mirror 15 is refracted by the lens 20 d and the lens 20 c and enters the galvanometer mirror 14. The second harmonic wave reflected by the galvanometer mirror 14 enters the beam splitter 13. The beam splitter 13 reflects a part of the incident light toward the photodetector 19. The light reflected by the beam splitter 13 is refracted by the lenses 20 i and 20 j and enters the fundamental wave cut filter 22. The fundamental wave cut filter 22 separates only the second harmonic from the fundamental wave and multiphoton excitation fluorescence that have propagated in the same direction as the second harmonic. That is, only the second harmonic wave passes through the fundamental wave cut filter 22 from the light incident on the fundamental wave cut filter 22 from the objective lens 16. The fundamental wave cut filter 22 can be the same as the fundamental wave cut filter 21 on the transmission side.

  Then, the second harmonic transmitted through the fundamental wave cut filter 21 enters the photodetector 19. The light incident on the photodetector 19 is collected by the lens 20 j and the like and enters the light receiving surface of the photodetector 19. The photodetector 19 is, for example, a two-dimensional photosensor such as a CCD camera. In order to effectively detect the second harmonic wave that is weak light, the light detector 19 is preferably provided with an image intifier. The photodetector 19 detects incident light and converts it into a video signal. The video signal is input to an image processing apparatus (not shown) that performs image processing, and the captured image is displayed on the display.

  By arranging the polarization control element 100 on the optical path, the second harmonic generated in the sample 30 is radiated backward. The mechanism by which the second harmonic is radiated backward will be described below. First, the effect when the above-described polarization control element 100 is arranged on the optical path will be described with reference to FIG. FIG. 6 is a diagram schematically showing a state of light propagation until the sample 30 is irradiated from the polarization control element 100 in order to explain the principle that the second harmonic is emitted backward. In FIG. 6, the configuration between the polarization control element 100 and the objective lens 16 is not shown.

  When the polarization control element 100 as shown in FIG. 4B is arranged on the optical path, a phase shift occurs between the light transmitted through the upper divided region 51 and the light transmitted through the lower divided region 55. That is, the phase of light is shifted by 180 ° between the divided region 51 and the divided region 55 that are arranged vertically opposite to each other. Assuming that linearly polarized light is output from the laser light, the phases of the orthogonal components of the electric vectors are in agreement. Due to the polarization control element 100, the phase of the electric vector is shifted by 180 ° between the divided region 51 and the divided region 55. That is, the vibration direction of the electric vector is opposite between the upper divided area 51 and the lower divided area 55. In the upper divided area 51 and the lower divided area 55, the polarization directions are opposite to each other. That is, the light transmitted through the upper divided region 51 and the light transmitted through the lower divided region 55 are linearly polarized light on the same straight line, but their vibration directions are opposite.

  The arrow in FIG. 6 schematically shows the vibration direction of the electric vector at that position in two dimensions. As described above, since the laser light before passing through the polarization control element 100 is linearly polarized, the electric vectors all oscillate in the same direction. By passing through the polarization control element 100, the vibration direction of the electric vector changes according to the position. The electric vector of the light transmitted through the upper divided region 51 is oscillating upward. On the other hand, the electric vector of the light transmitted through the lower divided region 55 oscillates downward. In FIG. 6, the vibration direction of light passing through the center is shown as an upward direction for the sake of explanation.

  A case where light in such a vibration direction is collected by the objective lens 16 will be described. The light transmitted through the upper divided area 51 is refracted by the objective lens 16 so as to be inclined downward. Therefore, the vibration direction of the electric vector of light is diagonally upward to the right as shown in FIG. Since the light transmitted through the center is not refracted by the objective lens 16, the vibration direction remains as it is upward. The light transmitted through the lower divided region 55 is refracted by the objective lens 16 so as to be inclined upward. Therefore, the vibration direction of the electric vector of light is diagonally downward to the right. In this way, light having different vibration directions depending on the position is collected on the sample.

  Next, the state where the light transmitted through the polarization control element 100 is condensed on the sample by the objective lens 16 will be described. Here, the vibration direction of the electric vector of light is considered by dividing it into a component (z component) in a direction parallel to a component perpendicular to the light traveling direction. In FIG. 6, a direction perpendicular to the light traveling direction is defined as the up-down direction, and a direction parallel to the light traveling direction is defined as the left-right direction.

  After passing through the objective lens 16, the vibration direction of the electric vector is diagonally right upward in the upper divided area 51 and diagonally lower right in the lower divided area 55, so the components in the vertical direction are opposite to each other. Thereby, in the state condensed on the sample, the vertical components in the vibration direction of the electric vector cancel each other. Therefore, the electric vector component in the direction perpendicular to the light traveling direction is substantially zero. That is, the electric vector of light does not vibrate in the direction perpendicular to the traveling direction on the sample.

  On the other hand, the vibration direction of the electric vector is diagonally right upward in the upper divided area 51 and diagonally lower right in the lower divided area 55, so that the components in the left-right direction are the same right direction. As a result, the left and right components of the electric vector are strengthened by the upper divided area 51 and the lower divided area 55. Accordingly, the electric vector component parallel to the light traveling direction is emphasized in the right direction. That is, the electric vector of light is oscillating in a direction parallel to the traveling direction. By condensing the laser light whose phase is shifted by the polarization control element 100 with the objective lens 16 in this manner, the sample 30 can be irradiated with light in a state where the electric vector vibrates in a direction parallel to the traveling direction. .

  Next, the principle that second harmonics are generated backward by irradiating the sample 30 with light while the electric vector vibrates in a direction parallel to the traveling direction will be described with reference to FIGS. FIG. 7 is a diagram schematically showing a second harmonic radiation pattern when the sample 30 is irradiated with light in a state where the electric vector vibrates in a direction parallel to the traveling direction. FIG. 8 is a diagram schematically showing a second harmonic radiation pattern when the sample 30 is irradiated with light in a state where the electric vector vibrates in a direction perpendicular to the traveling direction. That is, FIG. 7 shows the radiation pattern of the second harmonic in the SHG microscope according to the present embodiment in which the polarization control element 100 is arranged, and FIG. 8 shows a conventional SHG microscope in which the polarization control element 100 is not arranged. The radiation pattern of the 2nd harmonic in is shown.

  First, the radiation pattern of the second harmonic in the SHG microscope in which the polarization control element 100 is not disposed will be described with reference to FIG. In the state where the polarization control element 100 is not disposed, the electric vector of the light applied to the sample 30 oscillates in a direction perpendicular to the traveling direction. That is, when the polarization control element 100 is not disposed, even if light is collected by the objective lens 16, components in a direction parallel to the traveling direction cancel each other and become substantially zero. When light oscillating in a direction perpendicular to the traveling direction is irradiated, the polarized molecules oscillate in the vertical direction. As a result, a radiation pattern 40 as shown in FIG. 8 is obtained, and a second harmonic is generated in the forward direction. The second harmonic generated in the forward direction becomes a radiation pattern 40 that spreads with respect to the optical axis. That is, a broad second harmonic wave is generated in the same direction as the incident direction.

  On the other hand, the radiation pattern of the second harmonic in the SHG microscope according to the present embodiment in which the polarization control element 100 is arranged will be described. In the present embodiment, since the polarization control element 100 is disposed, the electric vector of the light irradiated on the sample 30 vibrates in a direction parallel to the traveling direction. When light oscillating in a direction parallel to the traveling direction is irradiated, the polarized molecules vibrate in the left-right direction. That is, the vibration direction of the polarized molecule differs depending on the vibration direction of the electric vector, and the radiation pattern 40 shown in FIG. 8 becomes a radiation pattern inclined by 90 °. The radiation pattern 40 spreads in the direction perpendicular to the traveling direction, and the second harmonic is generated backward as shown in FIG. That is, a broad second harmonic wave is generated in the same direction as the incident direction.

  Here, in order to increase the amount of the second harmonic radiated backward, it is preferable to use the objective lens 16 having a high numerical aperture. Thereby, the angle refracted by the objective lens 16 is increased, and the component that vibrates in the direction parallel to the traveling direction can be increased. For example, as shown in FIG. 3, when the angle of light collected by the objective lens 16 is α, the objective lens 16 having sin α = 0.9 to 0.95 is used. Thereby, the light quantity of the 2nd harmonic radiated back can be made sufficient. Further, in order to make the light amount of the second harmonic wave detectable by the photodetector 19, it is preferable that sin α ≧ 0.5. That is, by setting α ≧ 30 °, the light amount of the second harmonic can be detected by the photodetector 19. Note that the value of α described above is an exemplary value, and changes according to the light quantity of the laser light source, the performance of the optical system, the photodetector, and the like.

  The second harmonic wave thus emitted in the direction opposite to the traveling direction of the incident light is incident on the photodetector 19 through the objective lens 16 and the like. Then, a second harmonic image radiated rearward is picked up by the photodetector 19. As a result, it is possible to easily capture an SHG light image on an opaque sample such as a semiconductor or a thick sample such as a living body, and the field of application of the SHG microscope can be expanded.

  The polarization control element 100 is not limited to the SHG microscope, but can be used for a laser scanning fluorescence microscope, a Raman microscope, and a near-field microscope for detecting molecular orientation. Furthermore, it is also possible to use the above-described polarization control element 100 in order to increase the resolution of the microscope. In this manner, the laser light from the laser light source is incident on the polarization control element 100, and the laser light emitted from the polarization control element 100 is condensed by the objective lens and applied to the sample. Accordingly, the z component of the laser light can be increased or decreased with the laser microscope. Therefore, the field of application of the laser microscope can be expanded. Further, the microscope is not limited to the laser microscope, and may be a microscope in which linearly polarized light is incident.

  Next, the polarization state by the polarization control element 100 will be described with reference to FIGS. 9, 10, and 11. FIG. 9 is a diagram illustrating a result of measuring the z component of the electric vector when the light beam in the pseudo radial polarization state generated by the polarization control element according to the present embodiment is condensed. FIG. 10 is a diagram illustrating a result of measuring the z component of the electric vector when the light beam in the pseudo azimuth polarization state generated by the polarization control element according to the present embodiment is condensed. FIG. 11 is a diagram illustrating a measurement result when the polarization control element according to the present embodiment is not used.

  As shown in FIG. 9, when the pseudo radial polarization state is condensed, the z component is high in the vicinity of the central portion (x = 400 nm, near y = 500 nm). That is, the z component is strong on the optical axis. On the other hand, as shown in FIG. 11, in normal linearly polarized light, the z component becomes weak near the center. Note that in normal linearly polarized light, a phase difference occurs in the collected light when it is away from the vicinity of the center, so that the electric vector z component becomes higher at a position away from the vicinity of the center in the x direction. Further, when the 90 ° polarization control element 100 is rotated from the pseudo radial state, the pseudo azimuth polarization state is obtained. In the pseudo azimuth polarization state, the z component becomes weak and becomes substantially uniform in the xy space. Thus, it was confirmed that the polarization control element 100 generates a desired polarization state.

  As a method for measuring the z component of the electric vector, for example, “Y. Saito et al., Chemical Physics Letters 410 (2005) 136-141 Polarization measurement in a non-enhanced Raman spectroscopy”. The methods described can be used. In this method, a near-field probe is disposed on the back side of the sample to be collected. Then, the near-field probe is scanned along the sample surface. Thereby, the spatial distribution of the z component of the electric vector can be detected. Thus, it has been confirmed that the polarization control element according to the present embodiment can realize a predetermined polarization state, that is, pseudo radial polarization and pseudo azimuth polarization.

It is a figure which shows typically the structure of the polarization control element concerning Embodiment 1 of this invention. It is a figure which shows typically the polarization state of the light radiate | emitted from the polarization control element concerning Embodiment 1 of this invention. It is a figure which shows typically another polarization state of the light radiate | emitted from the polarization control element concerning Embodiment 1 of this invention. It is a figure which shows the manufacturing process of the polarization control element concerning Embodiment 2 of this invention. It is a figure which shows the structure of the SHG microscope in which the polarization control element concerning Embodiment 2 of this invention was used. It is a figure for demonstrating the vibration direction of the light radiate | emitted from the polarization control element concerning Embodiment 2 of this invention. It is a figure which shows the radiation pattern of a 2nd harmonic when pseudo radial polarization is condensed with the SHG microscope concerning Embodiment 2 of this invention. It is a figure which shows a measurement result when measuring the polarization state of the light which condensed normal linearly polarized light. It is a figure which shows a measurement result when measuring z component of the pseudo radial polarization state produced | generated by the polarization control element concerning this Embodiment 2. FIG. It is a figure which shows a measurement result when measuring z component of the pseudo azimuth polarization state produced | generated by the polarization control element concerning this Embodiment 2. FIG. It is a figure which shows a measurement result when z component when linearly polarized light is condensed is measured. It is a figure for demonstrating radial polarization and azimuth polarization.

Explanation of symbols

1 SHG microscope, 10 laser light source, 11 beam expander,
13 beam splitter, 14 galvanometer mirror, 15 galvanometer mirror,
16 objective lens, 17 objective lens, 18 photodetector, 19 photodetector,
20 lens, 21 fundamental wave cut filter, 22 fundamental wave cut filter,
30 samples, 40 radiation patterns, 50 substrates, 51-58 divided areas,
61 to 64 divided regions, 71 to 74 divided regions, 80 substrates, 81 substrates,
100 polarization control element,

Claims (7)

A polarization control element;
A light source that emits light incident on the polarization control element;
A microscope including an objective lens that collects light emitted from the polarization control element and irradiates the sample;
The polarization control element is
A polarization control element for converting linearly polarized light into radial polarized light or azimuth polarized light,
A divided region that is radially divided into eight or more, each having a divided region that is provided with a wave plate that emits light with the phase of incident light shifted;
A microscope in which optical axes of a pair of wave plates provided in divided regions facing each other are substantially orthogonal. The microscope according to claim 1, wherein the wave plate has a photonic crystal formed on the substrate. 2. The microscope according to claim 1, wherein the divided regions are formed by sticking radially divided wave plates to a substrate. The microscope according to claim 1, 2, or 3, wherein 16 divided regions are provided. The microscope according to claim 1, further comprising an identification mark for identifying the optical axis of the wave plate. A method of manufacturing a polarization control element for converting linearly polarized light into radial polarized light or azimuth polarized light by changing a polarization state of incident light according to an incident position,
Prepare multiple wave plates with optical axes in a given direction,
Each of the wave plates is radially divided so that the angle formed by the optical axis and the cutting line is different for each of the wave plates, and two or more divided regions are formed from the wave plates,
Selecting a predetermined number of divided regions from a plurality of divided regions formed from the plurality of wave plates;
Of the plurality of wave plates, a divided region selected from the first wave plate is attached to the first substrate ,
Next to the divided region selected from the first wave plate, the divided region selected from the second wave plate among the plurality of wave plates is pasted, and the optical axis of the wave plate in the opposed divided region Are arranged so that they are orthogonal ,
Of the divided regions divided from the first wave plate, a divided region that is not bonded to the first substrate is pasted on the second substrate,
The second of the divided regions divided from the wavelength plate, the first divided region that is not I stuck if the substrate, of the divided regions divided from said first wave plate in the second substrate A method of manufacturing a polarization control element that is bonded to the second substrate so as to be arranged next to each other. Each of the first substrate and the second substrate has four divided regions,
In the circumferential direction of the first substrate and the second substrate, the divided regions extracted from the first wave plate and the divided regions extracted from the second wave plate are alternately bonded. The method of manufacturing a polarization control element according to claim 6.