JP5917058B2 - Hologram manufacturing method and manufacturing apparatus - Google Patents

Description

  Embodiments described herein relate generally to a hologram manufacturing method and a manufacturing apparatus for drawing a hologram.

  Generally, when recording a hologram (diffraction grating) having a pattern on a photosensitive material, the following method is used. First, coherent light such as a laser is branched using a half mirror or beam splitter, the traveling direction of the light is changed by a mirror or the like, and one of the branched lights is irradiated to an object (hereinafter referred to as OBJ), The reflected light or transmitted light of the OBJ is applied to the photosensitive material. The other branched light is exposed to the same location. Two light beams exposed at the same position on the photosensitive material interfere with each other, and the interference fringes are recorded as a hologram.

  In this method, in order to record an OBJ image on a photosensitive material, it is necessary to expand or reduce the diameter of light from a light source according to the size of the OBJ using a lens or the like. Similarly, in the case where it is desired to enlarge or reduce the size of the pattern recorded on the photosensitive material, it is necessary to expand or reduce the light. Therefore, in order to irradiate light exceeding the threshold that can be recorded on the photosensitive material, a high output light source and a long drawing time are required. If the drawing time is long, the recorded pattern is likely to be affected by vibrations and may not be stable.

  In addition, a method has been proposed in which diffraction gratings having a size of an ellipsoid having a minor axis of 1 μm and a major axis of about 100 μm are arranged to make the aggregate into one hologram. In addition, a method has been proposed in which a relief is created on the material surface by changing the intensity of the electron gun or ion beam and the like, and the material surface is shaved to form a hologram.

Japanese Patent Laid-Open No. 9-6220 JP-A-11-52115 JP 2006-113429 A

  As described above, a relief (unevenness) is generated by light irradiation, so that it is not possible to give gradation to each image point in the method of producing a hologram. That is, the gradation cannot be expressed by the difference in the diffraction rate.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a method for producing a hologram that can stably draw a hologram with low output and can express gradation for each image point.

According to the embodiment, in the hologram manufacturing method, a dot having a specific size on the photosensitive material whose diffraction rate monotonously increases with a change in exposure time is defined as one dot, which is formed in accordance with hologram reproduction conditions. The light emitted from the light source is split into a plurality of light beams, and the branched light beams are condensed and superimposed on the photosensitive material from at least two directions to be drawn as a diffraction grating and observed during reproduction. By forming the 1 dot side by side on the photosensitive material based on the image data to be produced, a hologram is produced, and when drawing the 1 dot, the output of the diffraction grating to be drawn is maintained with the light source output constant. Dm maximum value of the diffraction index, an integer satisfying the Kw, 0 ≦ i ≦ Kw gradation expressed as i, the Dm ÷ Kw = alpha by the diffraction index i.alpha (i.alpha ≦ Dm) and comprising an exposure time, the photosensitive Material Reading from the relationship graph of the exposure time and the diffraction index of a method of drawing the 1 dot exposure time read.

FIG. 1 is a diagram schematically showing a hologram manufacturing apparatus according to the first embodiment. FIG. 2 is a graph showing the relationship between exposure time and diffraction rate when the output of the light source is constant. FIG. 3 is a plan view showing a light beam propagation state of the hologram manufacturing apparatus. FIG. 4A is a flowchart showing the operation of the apparatus when the output of the light source is constant. FIG. 4B is a flowchart showing a part of the flowchart of FIG. 4A in detail. FIG. 5 is a diagram showing a structural formula contained in azobenzene. FIG. 6 is a diagram showing a relationship between exposure time and diffraction rate when expressing five gradations. FIG. 7 is a diagram showing the relationship between the exposure time and the diffraction rate that express five gradations within a range that can be linearly approximated. FIG. 8 is a plan view schematically showing a hologram manufacturing apparatus according to a first modification using a concave mirror 9 instead of a reflecting mirror and a condensing lens. FIG. 9A is a plan view schematically showing a hologram manufacturing apparatus according to a second modification in which a lens is inserted after a condensing lens and exposed as parallel light. FIG. 9B is a plan view schematically showing a hologram manufacturing apparatus according to a third modified example in which a lens is inserted after collimation using a concave mirror and parallel light is exposed. FIG. 10 is a plan view schematically showing a hologram manufacturing apparatus according to a fourth modification including a mechanism for changing a drawing position by a polygon mirror. FIG. 11 is a plan view schematically showing a hologram production apparatus according to a fifth modification in which the number of branches is increased by a plurality of beam splitters or half mirrors. FIG. 12 is a plan view schematically showing a hologram manufacturing apparatus according to a sixth modification in which the number of branches is increased by a plurality of beam splitters or half mirrors. FIG. 13 is a plan view schematically showing a hologram manufacturing apparatus according to a seventh modification using a plurality of light sources and a beam splitter or half mirror. FIG. 14 is a plan view schematically showing a hologram manufacturing apparatus according to an eighth modification using a plurality of light sources and a beam splitter or half mirror. FIG. 15 is a flowchart showing a hologram manufacturing method according to a ninth modification. FIG. 16 is a flowchart showing a part of the flowchart shown in FIG. 15 in detail. FIG. 17 is a flowchart showing a hologram manufacturing method by the hologram manufacturing apparatus according to the second embodiment. FIG. 18 is a flowchart showing a part of the flowchart shown in FIG. 17 in detail. FIG. 19 is a graph showing the relationship between the light power density and the diffraction rate when the exposure time is constant. FIG. 20 is a diagram showing the relationship between the power density of light and the diffraction rate when expressing five gradations. FIG. 21 is a diagram illustrating a relationship between a power density and a diffraction rate that express five gradations within a range that can be linearly approximated. FIG. 22 is a diagram schematically showing an embodiment of a method in which a stage is brought into a positional relationship approaching the focal point of a lens. FIG. 23 is a diagram schematically showing an embodiment of a method for bringing the stage closer to the focal point of the concave mirror. FIG. 24 is a diagram schematically showing an embodiment of a method of making a positional relationship in which the position of a lens for parallel light approaches the focal point of a condenser lens. FIG. 25 is a diagram schematically showing an embodiment of a method of making a positional relationship in which the position of a lens for parallel light approaches the focal point of a concave mirror. FIG. 26 is a diagram schematically showing an embodiment in which the drawing position is changed by a polygon mirror among the embodiments in which the beam diameter is changed. FIG. 27 is a diagram schematically showing another embodiment in which the drawing position is changed by a polygon mirror among the embodiments in which the beam diameter is changed.

Hereinafter, embodiments will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 schematically shows the hologram manufacturing apparatus according to the first embodiment, and FIG. 2 shows the relationship between the exposure time and the diffraction rate when the output of the light source is constant when expressing gradation. FIG. 3 is an enlarged view of light propagation in the hologram manufacturing apparatus.

  As shown in FIGS. 1 and 3, a surface (relief) hologram manufacturing apparatus 100 controls a light source 1 that emits coherent light and a progression of coherent light oscillated from the light source 1, that is, controls shielding or passage. And a branching optical member such as a beam splitter or a half mirror 3 that splits the light that has passed through the shutter 2 into, for example, two lights. The hologram production apparatus has a stage 6 on which a photosensitive material 16 for rendering a hologram is placed, a reflection optical member that changes the traveling direction of the two separated light beams, for example, reflection mirrors 4a, 4b, and 4c, and two light beams. And two lenses 5a and 5b that are incident on the photosensitive material 16 on the stage 6 so that the two light beams overlap with each other.

  The stage 6 functioning as the changing means has a rotation axis in a direction perpendicular to both of the two light beams, and a stage having a mechanism capable of moving in at least two axial directions, a direction parallel to the rotation axis and a direction perpendicular to the rotation axis. It is. The stage 6 is installed so that there is an intersection of the two light beams on the drawing surface, and the drawing surface is parallel to the direction perpendicular to the rotation axis of the stage 6 and perpendicular to the bisector of the angle formed by the two light beams. To do.

  The hologram production apparatus 100 further includes a control device 7 that controls the light source 1, the opening / closing of the shutter 2, and the movement of the stage 6, and this control device 7 is connected to the light source, shutter, and stage by a cable 8. In the following description, unless otherwise noted, the light source 1, the shutter 2, and the stage 6 are assumed to be present in a state where they are connected to the control device 7 via the cable 8, and the illustration is omitted.

  In the hologram manufacturing apparatus 100, the progress of coherent light oscillated from the light source 1 is controlled by opening and closing the shutter 2, and the advanced light is branched by the beam splitter or the half mirror 3. Using the lenses 5a and 5b, the divergent two light beams are changed in the traveling direction by the reflecting mirrors 4a, 4b and 4c, respectively, and the angles between the two light beams are 10 to 50 degrees, for example, 30 degrees. Then, the light beam is condensed to a desired beam diameter, and the two light beams are incident on the photosensitive material 16 on the stage 6 so as to overlap each other, thereby recording the light interference fringes on the photosensitive material 16.

  As the photosensitive material 16, for example, a photosensitive material whose diffraction rate monotonously increases at least in a certain range of exposure time, such as azobenzene, or a photosensitive material whose diffraction rate monotonously increases at least in a certain range of light source power density. Use. FIG. 5 shows the most basic structural formula of azobenzene. An azobenzene compound always includes this structure, and a derivative formed by substituting the hydrogen part between the left and right benzenes has a basic structure in which N double bonds and N are between benzenes.

  The dots 11 formed by the interference fringes can control the diffraction rate by the release time of the shutter 2 controlled by the control device 7, that is, the exposure time, based on the exposure time and diffraction rate data as shown in FIG. it can. As shown in FIG. 1, the stage 6 is moved by the control device 7 and a plurality of dots 11 are arranged to record a desired image (hologram) 20 with the set of dots. That is, an area having a specific size on the photosensitive material 16 is defined as one dot, and one dot is formed by a diffraction grating according to the hologram reproduction condition, and the one dot is photosensitized based on image data observed during reproduction. Holograms are produced by arranging them on the material 16.

  4A and 4B are flowcharts showing the operation of the hologram manufacturing apparatus, that is, the hologram manufacturing method. As shown in FIG. 4A, the shutter 2 is closed when drawing starts (S11). When the shutter 2 is closed, the state is maintained. The image to be drawn is taken into the control device 7 (S12), and the resolution of the taken image is converted into the input desired resolution (S13). The pattern instruction data of the hologram pattern to be drawn is digital image data in a bitmap format, for example.

  The control device 7 performs gradation determination for each pixel after resolution change and determination of the exposure time for each pixel (S14). More specifically, as shown in FIG. 4B, the control device 7 reads the gradation (K) of the first pixel of the image (S14-1). Subsequently, the gradation (Kw: gradation inputted between S12 and S13) to express the maximum number of gradations (substantially the highest gradation + 1) of the image before the resolution change (hereinafter referred to as the original image). The value of the quotient obtained by dividing the gradation (K) of the first pixel by the quotient divided by) is substituted for Kn (S14-2).

It is assumed that i = 0 and whether Kn ≧ Kw−i is true or false is determined (S14-3). If false, i = i + 1 is substituted, and the determination is made again. If true, the value of i, that is, the maximum value of the diffraction grating to be drawn is set to Dm in accordance with the gradation of the pixel. As Dm ÷ Kw = α, each exposure time when the refractive index is iα (iα ≦ Dm) is set as the exposure time, which is a value read from the graph of exposure time and diffraction rate shown in FIG. 2 (S14-4). .

  Next, it is determined whether the gradation determination for all the pixels has been completed. If YES, the movement information to the drawing point and the exposure time at the drawing point, that is, the shutter release time are stored in the control device 7 (S15). If NO, the process returns to the gradation determination (S14-1) of the next pixel (S14-5).

  Subsequently, as shown in FIG. 4A, after the movement information to the drawing point and the exposure time information at the drawing point are stored in the control device 7 (S15), the stage 6 is moved based on this information to draw the drawing point. (S16). In this state, the control device 7 opens the shutter 2, emits light from the light source 1, and starts exposure (drawing) of the photosensitive material 16 (S17). Here, the light output from the light source 1 is constant. After the exposure time has elapsed, the control device 7 closes the shutter 2 (S18). Next, it is determined whether or not drawing has been completed (whether all pixels have been drawn) (S19). If NO, the process returns to the movement of the stage 6 (S16). If YES, drawing ends.

  A method for determining the exposure time when the gradation to be expressed is 5 will be described. As shown in FIG. 6, when the refractive index D is D = α, 2α, 3α, 4α, 5α (= Dm), a perpendicular line is drawn on the horizontal axis from the intersection point on the graph, and from the intersection point t1 between the perpendicular line and the horizontal axis. Let t5 be the exposure time for each gradation.

Alternatively, as shown in FIG. 7, by setting the maximum value Dm of the diffraction grating of the diffraction grating to be drawn to a range in which the relationship between the diffraction coefficient and the exposure time is linear or can be approximated as linear, the diffraction coefficient is 0 to the maximum value. The exposure time t1 to t5 of each gradation may be determined by calculating according to the following equation, where Tm is the time until Dm.
t = Tm ÷ Kw × i
The method is not limited to the above method as long as the exposure time for each gradation can be determined from the graph.

According to the hologram manufacturing apparatus 100 and the hologram manufacturing method configured as described above, when a hologram is drawn on a photosensitive material formed of an azobenzene material, the target image information is pointed and dots having gradation are formed. The light source output at the time of drawing can be reduced by drawing the hologram by arranging the dots. One dot can be drawn as a diffraction grating by converging interference from two directions after condensing the light of the branched light source using a lens. By focusing using a lens or the like, the power density can be increased to shorten the drawing time for one dot, reduce the influence of vibration during drawing, and stabilize the recorded image. be able to. It is possible to easily change the drawing size and the resolution of the completed image. When the output of the light source is made constant, the gradation of the hologram can be expressed by the difference in the diffractive index using the range where the relationship between the exposure time and the diffractive index increases monotonously. The gradation of the image can be expressed by adjusting the brightness for each dot. By scanning the stage on which the photosensitive material is placed, the size of the completed image can be arbitrarily and easily changed within the moving range of the stage. By setting the angle θ formed by the light branched in two directions to 10 to 50 degrees at the drawing point, the visibility of the completed hologram can be improved as shown in Table 1 below.

  Next, hologram production apparatuses and hologram production methods according to various modifications will be described. In the modification described below, the same parts as those of the first embodiment described above are denoted by the same reference numerals, and the detailed description thereof is omitted, and the parts different from those of the first embodiment are mainly described. This will be explained in detail.

(First modification)
FIG. 8 shows a hologram manufacturing apparatus 100 according to the first modification. In the first embodiment described above, the lens 5 is used as a means for collecting the light oscillated from the light source 1, but the reflecting mirrors 4a and 4c are changed to the concave mirrors 9a and 9b to collect the light, and the lens 5 is It is possible to combine the condensing by the lens and the condensing by the concave mirror by removing or changing only one of the two reflecting mirrors to a concave mirror.

(Second modification)
FIG. 9A shows a hologram manufacturing apparatus 100 according to a second modification. In the first embodiment described above, the light condensed by the lenses 5a and 5b is irradiated to the photosensitive material 16 as it is. However, after condensing, the lenses 10a and 10b are inserted and the two light beams are converted into parallel light. It is also possible to irradiate the photosensitive material 16.

(Third Modification)
FIG. 9B shows a hologram production apparatus 100 according to a third modification. In the first modification described above, the light collected by the concave mirrors 9a and 9b is directly irradiated to the photosensitive material 16, but after the light is collected, the lenses 10a and 10b are inserted to convert the two light beams into parallel light. The material 16 may be irradiated.

(Fourth modification)
FIG. 10 shows a hologram manufacturing apparatus 100 according to a fourth modification. In the first embodiment and the first to third modifications described above, the position of the drawing point is changed by moving the stage 6, but as shown in FIGS. A configuration may be adopted in which the position of the drawing point is changed by inserting a polygon mirror 12 or the like that functions as changing means later and changing the traveling direction of light. At this time, the control device 7 is connected to the drive unit of the polygon mirror 12 and controls the rotation of the polygon mirror.
By scanning light with a polygon mirror, the size of a completed image can be arbitrarily and easily changed within a range where light can be scanned with a polygon mirror.

(5th modification)
FIG. 11 shows a hologram manufacturing apparatus 100 according to a fifth modification. In the first embodiment and the first to third modifications described above, the number of times the light oscillated from the light source 1 is branched by the beam splitter or the half mirror 3 is one, but as shown in FIG. It is also possible to simultaneously draw two or more image points on the photosensitive material 16 by branching a plurality of times using the beam splitter or the half mirror 3. When changing the traveling direction of the light after branching, a plurality of light beams may be reflected by one reflecting mirror 4a, 4b, 4c.

(Sixth Modification)
FIG. 12 shows a hologram manufacturing apparatus 100 according to a sixth modification. When a plurality of beam splitters or half mirrors 3 are used to branch a light beam a plurality of times and two or more image points are simultaneously drawn on the photosensitive material 16 as in the fifth modification, as shown in FIG. A plurality of reflecting mirrors 4a, 4b, 4c may be used in accordance with the number of mirrors. Further, the position of the shutter 2 only needs to have a function of blocking one of the two light beams superimposed at the drawing point on the light beam that is not branched thereafter. It is also possible to use a concave mirror 9 instead of the plurality of reflecting mirrors 4a, 4b, 4c and the condenser lens 5. The position of the shutter 2 is not necessarily placed after the beam splitter or the half mirror 3, and can be placed immediately after the light source 1 or on one of the branched light beams.

(Seventh Modification)
FIG. 13 shows a hologram manufacturing apparatus 100 according to a seventh modification. In the fifth and sixth modifications described above, the light emitted from the light source 1 is branched a plurality of times by using a plurality of beam splitters or half mirrors 3 for one light source 1, but as shown in FIG. A plurality of light sources 1 may be provided, and light emitted from these light sources may be branched once by one beam splitter or half mirror 3. When changing the traveling direction of the branched light, a plurality of light beams may be reflected by each of the reflection mirrors 4a, 4b, and 4c.

(Eighth modification)
FIG. 14 shows a hologram manufacturing apparatus 100 according to a seventh modification. When a plurality of light sources 1 are used to divide a light beam into a plurality of parts and simultaneously draw two or more dots on the photosensitive material 16 as in the seventh modification, as shown in FIG. A plurality of reflecting mirrors 4a, 4b, 4c may be used. Further, the position of the shutter 2 only needs to have a function of blocking one of the two light beams superimposed at the drawing point on the light beam that is not branched thereafter. It is also possible to use a concave mirror 9 instead of the plurality of reflecting mirrors 4a, 4b, 4c and the condenser lens 5. The position of the shutter 2 is not necessarily placed after the beam splitter or the half mirror 3, and can be placed immediately after the light source 1 or on one of the branched light beams.

(Ninth Modification)
15 and 16 show a flowchart of a hologram manufacturing method according to the ninth modification. In the first embodiment described above, gradation determination and exposure time determination are performed for all pixels before moving to the first drawing point. However, as shown in FIGS. It is also possible to determine the gradation of the next pixel and determine the exposure time.

  Next, a hologram manufacturing method according to another embodiment will be described. In the embodiments described below, the same parts as those in the first embodiment described above are denoted by the same reference numerals, and the detailed description thereof is omitted. The parts different from those in the first embodiment are mainly described. This will be explained in detail.

(Second Embodiment)
17 and 18 are flowcharts showing the operation of the hologram manufacturing apparatus according to the second embodiment, that is, the hologram manufacturing method. FIG. 19 is a light source when the exposure time is constant when expressing gradation. The relationship between the power density and the diffraction rate is shown. The hologram manufacturing apparatus can use the same configuration as that of the first embodiment described above.

  In the first embodiment, the output of the light source is fixed and the exposure time is changed to adjust the diffraction rate, that is, the gradation. However, in the second embodiment, the exposure time is fixed and the light source is adjusted. The gradation of the hologram to be drawn is expressed by changing the power density.

  As shown in FIGS. 17 and 18, in the second embodiment, the shutter 2 is closed when drawing is started (S21). When the shutter 2 is closed, the state is maintained. The image to be drawn is taken into the control device 7 (S22), and the resolution of the taken image is converted into the input desired resolution (S23). The pattern instruction data of the hologram pattern to be drawn is digital image data in a bitmap format, for example.

  The control device 7 determines the gradation for each pixel after the resolution change and determines the exposure time for each pixel (S24). More specifically, as shown in FIG. 4B, the control device 7 reads the gradation (K) of the first pixel of the image (S24-1). Subsequently, the gradation (Kw: gradation inputted between S12 and S13) to express the maximum number of gradations (substantially the highest gradation + 1) of the image before the resolution change (hereinafter referred to as the original image). The value of the quotient obtained by dividing the gradation (K) of the first pixel by the quotient divided by) is substituted for Kn (S24-2).

It is determined that i = 0 and whether Kn ≧ Kw−i is true or false (S24-3). If false, i = i + 1 is substituted, and the determination is made again. If true, the value of i, that is, the maximum value of the diffraction grating to be drawn is set to Dm in accordance with the gradation of the pixel. Assuming that Dm ÷ Kw = α, the output of the light source 1 having a diffraction rate iα (iα ≦ Dm) is multiplied by the value read from the power density and diffraction rate graph shown in FIG. 19 and the exposure area calculated from the beam diameter. Is set as the output of the light source (S24-4).

  Next, it is determined whether the gradation determination for all pixels has been completed. If YES, the movement information to the drawing point and the light source output at the drawing point are stored in the control device 7 (S25). Returns to the gradation determination (S24-1) of the next pixel (S24-5).

  Subsequently, as shown in FIG. 4A, after the movement information to the drawing point and the exposure time information at the drawing point are stored in the control device 7 (S25), the stage 6 is moved based on this information to draw the drawing point. (S26). In this state, the control device 7 opens the shutter 2, emits light from the light source 1, and starts exposure (drawing) of the photosensitive material 16 (S27). After the exposure time has elapsed, the control device 7 closes the shutter 2 (S28). Next, it is determined whether or not drawing has been completed (whether all pixels have been drawn) (S29). If NO, the process returns to the movement of the stage 6 (S26). If YES, drawing ends.

  A method of determining the light source output when the gradation to be expressed is 5 will be described. As shown in FIG. 20, when the refractive index D is D = α, 2α, 3α, 4α, 5α (= Dm), a perpendicular line is drawn on the horizontal axis from the intersection point on the graph, and from the intersection point P1 between the perpendicular line and the horizontal axis. P5 is the power density of each gradation, and this is multiplied by the exposure area to obtain the output of the light source.

Alternatively, as shown in FIG. 21, the maximum value Dm of the diffraction grating of the diffraction grating to be drawn is set to a range where the relationship between the diffraction coefficient and the power density is linear or can be approximated as linear, so that the diffraction coefficient is 0 to the highest value. The power density up to Dm may be calculated as Pm according to the following formula, the power density Pd may be determined, and the output P of the light source may be determined.
Pd = Pm ÷ Kw × i
P = Pd × (beam diameter at drawing point) ² ÷ (beam diameter of light source) ²
Note that the method is not limited to the above method as long as the power density for each gradation can be determined from the graph.

According to the hologram manufacturing apparatus and the hologram manufacturing method configured as described above, when a hologram is drawn on a photosensitive material formed of an azobenzene material, the target image information is pointed and dots having gradation are formed, By arranging the dots and drawing the hologram, it becomes possible to reduce the light source output at the time of drawing. The drawing size and the resolution of the completed image can be easily changed, and the drawing time for one dot can be shortened to stabilize the recorded image. When the exposure time is made constant, the gradation can be expressed by the difference in the diffractive index using the range where the relationship between the power density of the light source and the diffractive index increases monotonously. The gradation of the image can be expressed by adjusting the brightness for each dot.
Also in the second embodiment described above, the first to ninth modifications described above can be applied. Further, the control of the output of the light source is not limited to electronic control by the control device, and the output of the light source is controlled by arranging a plurality of ND filters having different transmittances, for example, in a circular shape and mechanically replacing them by rotation. It is also possible.

Next, a method for changing the resolution of a hologram to be drawn will be described with reference to FIGS. The resolution is changed by adjusting the positions of the lens 5, the concave mirror 9, the lens 10, the stage 6, and the like of the hologram manufacturing apparatus 100 shown in the first embodiment.
When the resolution is doubled without changing the size of the completed image, it can be realized by drawing with the diameter of the completed dot to be drawn being halved. As shown in FIG. 22, the dot diameter is halved by moving the stage 6 to a position approaching the focal point of the lens 5 or moving the lens 5 and bringing the focal point closer to the stage 6. Further, as shown in FIG. 23, there are a method of moving the stage 6 to a position approaching the focal point of the concave mirror 9 or a method of moving the concave mirror 9 and bringing its focal point closer to the stage 6. As shown in FIG. 24, the position of the lens 10 shown in FIG. 9A is set to a positional relationship approaching the focal point of the lens 5, and as shown in FIG. 25, the position of the lens 10 shown in FIG. There is a method to make the position close to the focal point.

  In the method described above, all the collected light or the collimated light is irradiated to the drawing point on the stage, but as long as the drawing point is irradiated with a beam diameter that achieves the desired resolution. As shown in FIGS. 26 and 27, the drawing position can be changed by the polygon mirror 12 or the like.

  By the above method, the resolution of the recorded image can be easily changed by changing the diameter of the light incident on the photosensitive material 16, the beam diameter of the light source, the focus of the lens, or the degree of condensing by a concave mirror or the like. Can do.

The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
Hereinafter, the description of the scope of claims at the beginning of application of the present application will be added.
[1]
A method for producing a hologram by a direct drawing method by making light incident on a photosensitive material containing azobenzene,
An area of a specific size on the photosensitive material is defined as one dot, the one dot is formed by a diffraction grating according to hologram reproduction conditions, and the one dot is exposed to light based on image data observed during reproduction. A hologram production method for producing a hologram by forming it side by side on a material.
[2]
The light emitted from the light source is branched into a plurality of light fluxes, and the branched light fluxes are collected and overlapped and interfered on the photosensitive material from at least two directions, thereby drawing one dot as a diffraction grating [1] The hologram production method as described.
[3]
The hologram production method according to [2], wherein a position on which the dots of the diffraction grating are drawn is changed by moving a stage on which the photosensitive material is placed.
[4]
The hologram production method according to [2], wherein the position where the dots of the diffraction grating are drawn is changed by scanning the branched light flux.
[5]
When the one dot is drawn, the output of light is constant, and the exposure time of one dot is changed according to the gradation, so that the dots to be drawn have gradation characteristics [1] to [4] Any one of the hologram production methods.
[6]
When the maximum gradation of the original image to be drawn is Km and the gradation to be expressed is Kw, the gradation K of a certain pixel is converted to the gradation Kn to be expressed according to the following formula,
Kn = K ÷ {(Km + 1) ÷ Kw}
I is sequentially increased from 0 until the obtained Kn reaches Kn ≦ Kw−i (where i is an integer satisfying 0 ≦ i ≦ Kw), and i is drawn when Kn ≦ Kw−i is satisfied. The hologram production method according to [5], in which gradation is determined.
[7]
In accordance with the determined gradation, with the output of the light source being constant, the maximum value of the diffraction grating to be drawn is Dm, Dm ÷ Kw = α, and the diffraction coefficient is iα (iα ≦ Dm). The hologram production method according to [6], wherein the exposure time t is determined as a value obtained by reading each exposure time obtained from the relationship graph between the exposure time and the diffraction rate.
[8]
In accordance with the determined gradation, with the output of the light source being constant, the maximum value Dm of the diffraction grating to be drawn is set to a range in which the relationship between the diffraction coefficient and the exposure time is linear or can be approximated as linear. Thus, the hologram preparation method according to [7], wherein the exposure time t is calculated according to the following formula: t = Tm ÷ Kw × i, where Tm is the time from when the refractive index reaches 0 to the maximum value Dm.
[9]
When the one dot is drawn, the exposure time of the one dot is fixed, and the power density of the light source is changed according to the gradation, so that the dot to be drawn has gradation characteristics [1] to [4] ] The hologram manufacturing method in any one of.
[10]
When the maximum gradation of the original image to be drawn is Km and the gradation to be expressed is Kw, the gradation K of a certain pixel is converted to the gradation Kn to be expressed according to the following formula,
Kn = K ÷ {(Km + 1) ÷ Kw}
I is sequentially increased from 0 until the obtained Kn reaches Kn ≦ Kw−i (where i is an integer satisfying 0 ≦ i ≦ Kw), and i is drawn when Kn ≦ Kw−i is satisfied. The hologram production method according to [9], in which gradation is determined.
[11]
In accordance with the determined gradation, with the exposure time constant, the maximum value of the diffraction grating of the diffraction grating to be drawn is set as Dm, and Dm ÷ Kw = α, and the diffraction rate is iα (iα ≦ Dm). The hologram production method according to [10], wherein each power density P1 to Pi is determined as a value read from a relationship graph between the power density and the diffractive index.
[12]
In accordance with the determined gradation, with the exposure time constant, the maximum value Dm of the diffraction grating to be drawn is within a range in which the relationship between the diffraction coefficient and the power density of the light source is linear or can be approximated as linear. Then, the hologram density producing method according to [10], wherein the power density from 0 to the maximum value Dm is calculated as Pm according to the following formula: P = Pm ÷ Kw × i.
[13]
A light source that oscillates light;
An openable shutter that blocks light from the light source,
A branching optical member that branches light oscillated from a light source in two directions;
A reflective optical member that changes the traveling direction of light;
A lens that collects the light;
A stage for supporting a photosensitive material containing adbenzene;
Changing means for moving the stage or scanning the light to change the irradiation position of the light on the photosensitive material;
A controller that controls the opening and closing of the shutter, the opening and closing time thereof, and the operation of the changing unit, and condenses the branched light flux and causes the overlapping and interference on the photosensitive material from at least two directions, A hologram production apparatus for drawing one dot on the photosensitive material as a diffraction grating.
[14]
The hologram production apparatus according to [13], wherein an angle formed by the light beams in the two directions is 10 to 50 degrees at a drawing point.

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Shutter, 3 ... Beam splitter or half mirror 4a, 4b, 4c ... Reflection mirror, 5a, 5b ... Lens, 6 ... Stage, 7 ... Control apparatus,
8 ... Cable, 9 ... Concave mirror, 10 ... Lens, 11 ... Diffraction grating dot,
12 ... polygon mirror, 13 ... lens, 14 ... reflection mirror,
16 ... Sensitive material

Claims (12)

A method for producing a hologram comprising:
The light emitted from the light source is formed as one dot corresponding to the hologram reproduction condition, with a region having a specific size on the photosensitive material containing azobenzene whose diffractive index monotonously increases as the exposure time changes. Is divided into a plurality of light beams, and the branched light beams are collected and overlapped and interfered on the photosensitive material from at least two directions, thereby drawing as a diffraction grating and based on image data observed during reproduction. A hologram is produced by forming one dot side by side on the photosensitive material,
When drawing one dot, with the output of the light source constant, the maximum value of the diffraction grating to be drawn is Dm, the gradation to be expressed is Kw , and an integer satisfying 0 ≦ i ≦ Kw is i , A hologram manufacturing method for reading the exposure time when the refractive index becomes iα (iα ≦ Dm) by Dm ÷ Kw = α from the graph of the relationship between the exposure time and the diffraction rate in the photosensitive material and drawing the one dot with the read exposure time .   2. The hologram manufacturing method according to claim 1, wherein an angle formed by the light beams in the two directions is 10 to 50 degrees at a drawing point.   The hologram production method according to claim 1, wherein a position on which the dots of the diffraction grating are drawn is changed by moving a stage on which the photosensitive material is placed.   The hologram production method according to claim 1, wherein a position where the dots of the diffraction grating are drawn is changed by scanning the branched light beam. When the maximum gradation of the original image to be drawn is Km and the gradation to be expressed is Kw, the gradation K of a certain pixel is converted to the gradation Kn to be expressed according to the following formula,
Kn = K ÷ {(Km + 1) ÷ Kw}
The obtained Kn is incremented sequentially from 0 until Kn ≧ Kw−i (where i is an integer satisfying 0 ≦ i ≦ Kw), and i is determined when Kn ≧ Kw−i is satisfied. The hologram production method according to claim 1.   In accordance with the determined gradation, with the output of the light source being constant, the maximum value Dm of the diffraction grating to be drawn is set to a range in which the relationship between the diffraction coefficient and the exposure time is linear or can be approximated as linear. The hologram production method according to claim 5, wherein the exposure time t is calculated according to the following expression: t = Tm ÷ Kw × i, where Tm is the time from when the refractive index reaches 0 to the maximum value Dm. A method for producing a hologram comprising:
A dot of a specific size on the photosensitive material containing azobenzene whose diffraction rate monotonously increases with the change in the power density of the light source is taken as 1 dot, and 1 dot formed according to the hologram reproduction condition is emitted from the light source. Based on the image data that is drawn as a diffraction grating by converging the split light into a plurality of light fluxes, condensing the split light fluxes and overlapping and interfering on the photosensitive material from at least two directions. The hologram is produced by forming the one dot side by side on the photosensitive material, and when the one dot is drawn, the maximum value of the diffraction grating to be drawn is set to Dm with a constant exposure time. the integer satisfying the gradation to express Kw, 0 ≦ i ≦ Kw as i, the power density diffraction rate is iα (iα ≦ Dm) by Dm ÷ Kw = α, the power of the light-sensitive material Reading from the relationship graph in degrees and the diffraction index, a hologram manufacturing method for drawing the one dot power density read. When the maximum gradation of the original image to be drawn is Km and the gradation to be expressed is Kw, the gradation K of a certain pixel is converted to the gradation Kn to be expressed according to the following formula,
Kn = K ÷ {(Km + 1) ÷ Kw}
The obtained Kn is incremented sequentially from 0 until Kn ≧ Kw−i (where i is an integer satisfying 0 ≦ i ≦ Kw), and i is determined when Kn ≧ Kw−i is satisfied. The hologram production method according to claim 7.   In accordance with the determined gradation, with the exposure time constant, the maximum value Dm of the diffraction grating to be drawn is within a range in which the relationship between the diffraction coefficient and the power density of the light source is linear or can be approximated as linear. The hologram production method according to claim 8, wherein the calculation is performed according to the following formula: P = Pm ÷ Kw × i, where Pm is a power density at which the refractive index is 0 to the maximum value Dm. A light source that oscillates light;
An openable shutter that blocks light from the light source,
A branching optical member that branches light oscillated from a light source in two directions;
A reflective optical member that changes the traveling direction of light;
A lens that collects the light;
A stage for supporting a photosensitive material containing A zone benzene diffraction rate increases monotonically with respect to the change of the exposure time,
Changing means for moving the stage or scanning the light to change the irradiation position of the light on the photosensitive material;
A controller that controls the opening and closing of the shutter, the opening and closing time thereof, and the operation of the changing means,
The control unit condenses the branched light flux and overlaps and interferes on the photosensitive material from at least two directions, thereby making the output of the light source constant when drawing one dot as a diffraction grating on the photosensitive material. In the state, assuming that the maximum value of the diffraction index of the diffraction grating to be drawn is Dm, the gradation to be expressed is Kw , and the integer satisfying 0 ≦ i ≦ Kw is i, the diffraction index is iα (iα ≦ Dm) by Dm ÷ Kw = α. A hologram production apparatus that reads the exposure time from the graph of the relationship between the exposure time and the diffractive index of the photosensitive material and draws the one dot with the read exposure time.   11. The hologram manufacturing apparatus according to claim 10, wherein an angle formed by the light beams in the two directions is 10 to 50 degrees at a drawing point. A light source that oscillates light;
An openable shutter that blocks light from the light source,
A branching optical member that branches light oscillated from a light source in two directions;
A reflective optical member that changes the traveling direction of light;
A lens that collects the light;
A stage for supporting a photosensitive material containing A zone benzene diffraction rate increases monotonically with respect to changes in the power density of the light source,
Changing means for moving the stage or scanning the light to change the irradiation position of the light on the photosensitive material;
A controller that controls the opening and closing of the shutter, the opening and closing time thereof, and the operation of the changing means,
The control unit condenses the branched light beam and overlaps and interferes on the photosensitive material from at least two directions, thereby rendering the exposure time constant when drawing one dot as a diffraction grating on the photosensitive material. Where Dm is the maximum value of the diffraction grating to be drawn, Kw is the gradation to be expressed , i is an integer satisfying 0 ≦ i ≦ Kw, and the refractive index is iα (iα ≦ Dm) by Dm ÷ Kw = α. A hologram production apparatus that reads the power density from the relationship graph between the power density and the diffractive index of the photosensitive material and draws the one dot at the read power density.

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