JPH03269343A - Irradiation optical system - Google Patents

Abstract

PURPOSE:To uniform the distribution of light intensity in the horizontal direction without reducing the using efficiency of irradiation light by dividing luminous flux in the longitudinal direction of face to be irradiated symmetrically around the center and superposing the luminous flux of respective sections on the face to be irradiated in the longitudinal direction. CONSTITUTION:Luminous flux beams projected from a coherent light source 2 is deflected by a phase modulation optical element 4. When it is defined that the width of the element 4 rectangular to the incident flux is D, the width of face to be irradiated 6 is Dx and the width of each section obtained by dividing the width D into N symmetrically around the center is (d), luminous flux projected from an optional n-th section (dn) is expanded to the width Dx on the irradiated face 6. Since cylindrical waves projected from respective section (dn) are superposed on the 1 face 6, the incident beams on the center part can illuminate the peripheral part of the face 6, so that the distribution of light intensity can be further uniformed.

Description

[Detailed Description of the Invention] 4 [Industrial Application Field] The present invention relates to an irradiation optical system, and particularly to an irradiation optical system for uniformly irradiating small objects in a cell analyzer. be.

[Conventional technology]

A conventional cell analyzer has a cross-sectional area of 200 x 200 μm.
A glass cell with a diameter of about 2 mm, an irradiation optical system that illuminates cells flowing in the center of the cell surrounded by a liquid such as physiological saline at right angles to the direction of their movement, and fluorescence and scattering caused by the light irradiated onto the cells. and a detection system that detects light.

The cell analyzer uses detected fluorescence and scattered light to
It obtains information about the shape of cells and the substances inside them.

If there is a distribution in the irradiation light intensity, if the flow of cells deviates from the center of the cell due to disturbances in the cell shape or guide fluid flow, the detection signal will change and measurement accuracy will decrease. .

Conventionally, attempts have been made to address this problem by adding transmittance distribution filters, cylindrical lenses, etc. to the irradiation optical system in an effort to make the horizontal light intensity distribution constant. in particular,
A cylindrical lens is inserted horizontally so that it is perpendicular to the incident light flux, and a transmittance distribution filter with low light transmittance in the center is inserted to cancel out the Gaussian light intensity distribution of the light source. Measures are being taken. Examples of this type of prior art include Japanese Patent Laid-Open No. 83633/1983.

[Problem to be solved by the invention]

The above-mentioned conventional technology has a problem in that the degree of uniformity of the horizontal light intensity distribution of the irradiated light is insufficient, and when the flow of cells is disturbed, the measurement accuracy decreases.

In addition, since a transmittance distribution filter is used to attenuate the light in the bright central area to make the overall illuminance uniform, the utilization efficiency of the irradiated light is low, making it difficult to miniaturize the light source.

An object of the present invention is to provide an irradiation optical system equipped with means for making the horizontal light intensity distribution more uniform without reducing the utilization efficiency of irradiation light.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an irradiation optical system that illuminates a horizontally long irradiated surface with a light beam emitted from at least one light source with an axially symmetrical intensity distribution. The present invention proposes an irradiation optical system including a phase modulation optical element that divides the beam symmetrically in the longitudinal direction and superimposes the light beams of each section in the longitudinal direction on the irradiated surface.

More precisely, the XY
It is parallel to the plane and symmetrical to the XZ plane and YZ plane, the width in the X axis direction is DX, the width in the Y axis direction is DY, and the two-axis coordinate f (
In the irradiation optical system that illuminates the irradiated surface located at f>0), it is arranged approximately at the origin of the XY2 orthogonal coordinate system, the number of divisions is N (N≧2), and the width of the incident light beam in the X-axis direction is (DX ×
N), the irradiated surface is divided into N equal parts symmetrically about the yz plane, and the wavefront of each section is translated in parallel on the irradiated surface to deflect the incident light flux in the positive and negative directions of the Y-axis and converge on the irradiated surface. This paper proposes an irradiation optical system equipped with a phase modulation optical element that allows

The light emitting device may include an acousto-optic element that controls the amplitude and phase modulation function of the phase modulation optical element and changes the position of the light beam on a plane orthogonal to the incident light beam.

When the irradiation optical system includes a number of phase modulating optical elements corresponding to the plurality of irradiated surfaces and an optical element that divides the light flux from the light source to each phase modulating optical element, it is possible to cover the plurality of irradiated surfaces. Can be lit all at once.

The entire phase modulation optical element can be miniaturized if it is made into a composite element in which at least a portion of the optical element is integrated in at least one of the directions from the light source toward the irradiated surface and the direction perpendicular to this direction.

By using these irradiation optical systems, you can create an irradiation optical system that irradiates an object moving approximately in the Y-axis direction near X=0, Z=f of the XYZ orthogonal coordinate system, and a detection system that detects the scattered light generated by the irradiation. An object shape measuring device is obtained, which includes a signal processing system that obtains data such as the shape of an object using detection signals from the detection system.

Object 8- using a detector that detects scattered light and fluorescence It can also be used as a shape fluorescence measuring device.

The phase modulation optical element can be provided in the form of an aspherical bulk lens, a blazed grating, a hologram, a blazed hologram, or the like.

In either case, an acousto-optic element may be provided that controls the amplitude and phase modulation function of the phase modulation optical element and changes the position of the output light beam with respect to a plane orthogonal to the input light beam.

The present invention further provides an image sensor disposed at a position of the irradiated surface of the phase modulating optical element, and an image processing device that processes signals from the image sensor and displays an intensity profile of the irradiated light beam on the irradiated surface. and means for adjusting the position of at least one of the phase modulating optical elements of the light source 9 according to the intensity profile of the irradiation light beam, etc. It is something to do.

[Effect]

The phase modulation optical element of the present invention separates the incident light beam into a plurality of sections symmetrically with respect to the center, and deflects the divided output light beams so that they are overlapped symmetrically with the center on the irradiated surface, so that, for example, a Gaussian intensity distribution is achieved. The light beam in the central section of the incident light beam having a radius illuminates the peripheral portion of the irradiated surface, resulting in a much more uniform illuminance than in the past.

At this time, the light utilization efficiency does not decrease because the conventional means of reducing light by changing the transmittance is not used.

Therefore, when this phase modulation optical element is applied to, for example, a cell analyzer, even if the position of the small object shifts in the left and right peripheral directions within the irradiated surface, it is possible to use the scattered light and fluorescence from the small object. The measurement accuracy of shape measurement and substance measurement inside objects is improved.

〔Example〕

Next, the present invention will be described in detail with reference to the drawings.

Fig. 2 is a diagram illustrating an embodiment of the irradiation optical system employing the phase modulation optical element according to the present invention, Fig. 2 is a diagram illustrating the function of the phase modulation optical element of the embodiment shown in Fig. FIG. 4 is a diagram illustrating in more detail the characteristics of a phase modulation optical element that irradiates one irradiated surface. FIG. 4 is a diagram showing the relationship between the position on the irradiated surface and the light intensity distribution.

In FIG. 1, a beam of light emitted from a coherent light source 2 is deflected by a phase modulation optical element 4 according to the present invention, and illuminates an irradiated surface 6.

The function of the phase modulation element 4 at that time will be explained with reference to FIG. If the width perpendicular to the incident light beam of the phase modulation optical element 4 is D, the width of the irradiated surface 6 is Dx, and the width of one division obtained by dividing the width into N equal parts centrally symmetrically is d, then any nth Category dn
The luminous flux emitted from the light beam spreads to a width Dx on the irradiated surface 6.

Since the cylindrical waves emitted from the respective sections dn overlap on the irradiated surface 6 in a center-symmetrical manner, the incident light beam at the center can illuminate the peripheral portion of the irradiated surface 6, making the light intensity distribution more uniform.

In order to superimpose the emitted light beams on the irradiated surface 6 in this manner, the phase modulation optical element 4 becomes a linear grating whose pitch changes within the section. If the center coordinates of the n-th section are d-n, and the displacement 1-position from the center coordinates is η, then the pitch An(η
) is expressed by equation (1).

The phase modulating optical element 4 converts the incident light beam from a plane wave to a cylindrical wave, and superimposes the waves symmetrically on the irradiated surface 6. As a result, the light intensity distribution on the irradiated surface 6 is made more uniform.

FIG. 3 is a diagram more specifically showing the case where the incident light beam is divided into two and one irradiated surface 6 is irradiated.

The phase modulation optical element shown in FIG. 3(a) converts a coherent incident light beam 31 that advances in the positive direction on the Z-axis and has a light intensity distribution symmetrical to the YZ plane into two planes p1 and 2 parallel to the XY plane. It has a function of phase modulating with p2. Its size is X, Y, Z
The directions are DXDXW, respectively, and the plane P1 is placed on the XY plane, and the center is placed on the origin. The irradiated surface 6 has a size of DXXDY, is parallel to the XY plane, and is located at f from the origin. It is assumed that the size of the incident light beam is larger than the size of the optical element.

2- As shown in Fig. 3(c), a coherent incident beam 3
1 enters the phase modulation optical element 4, two phase modulation elements 4a exist on the plane P□.

4b, the emitted light beams 34a and 34b are deflected by 10 and θ, and are superimposed on the irradiated surface 6.

Here, the light waves incident on the two phase modulation elements 4a and 4b have only the electric field of the y-direction component, and the beam diameter is 2a,
Assuming that t and z are constant, each component is expressed by equation (2).

2a: Beam diameter Here, the beam diameter of the incident beam with Gaussian distribution type light intensity distribution is 2a, and the intensity distribution function of the incident beam is
The electric field distribution function E, (x) obtained by dividing the area into N equal parts in the axial direction and linearly approximating each section is expressed by equation (3).

+□ (e-"'type)'-8-(H), -(π),...
(3) However, xn-1<X<Xn, Xn= , n Furthermore, the electric field on the irradiated surface 6 is expressed by equation (4).

1 (x)=I el(x)+e,(x)l'''
-...- (4) Therefore, the light intensity distribution function I(x) on the irradiated surface 6 is expressed by equation (5).

I (x) = 4 (b n -a n xo)2co
s2kx−x・・・・・・(5) However, −1 b, =Eo(ne −(N ”−(n−1)e−(
N)) In Figure 4, the wavelength of the incident light is λ = 488 nm, the beam diameter 2a = 200 μm, the width of the irradiated surface DX = 00 μm, and D
FIG. 6 is a diagram showing the calculation results of equation (5) when Y=2 μm and the distance between the origin and the irradiated surface is 200 μm.

In this case, interference fringes with a pitch of 1 μm are generated, but since the object to be irradiated is a cell with a diameter of about 20 to 30 μm, these interference fringes can be ignored.

Furthermore, the rate of decrease in light intensity with respect to the center at a point 507 zm away from the center in the % reduction.

Furthermore, when the phase modulating optical element 4 of the present invention is used, the light intensity near the center is approximately 3.3 times as high as when using a conventional transmittance distribution filter.

That is, when using the phase modulation optical element 4 of the present invention,
Over a region of ±50 μm in the X-axis direction of the irradiated surface 6, the rate of change in light intensity was improved by 49%, and the light intensity itself was approximately 3.3
It will be twice as strong and the efficiency of light usage will be improved.

On the other hand, in the Y-axis direction, the phase modulation element located on the plane P2 of the phase modulation optical element 4 directs the incident light beam 31 to a straight line z separated by f from the origin, as shown in FIG. 3(d).
=f15- However, due to diffraction, the light beam spreads in the Y-axis direction by a size DY expressed by equation (6).

Moreover, the intensity distribution is as shown in equation (7).

However, J□(x) is a Bessel function. By making the incident light beam 31 having a symmetrical light intensity distribution in the X-axis direction enter the phase modulation optical element 4 equipped with two-plane phase modulation elements, As shown in FIG. 3(b), illumination light having a peak at the center in the Y-axis direction and a substantially constant light intensity distribution in the X-axis direction can be obtained on the illuminated surface 6.

FIG. 5 is a diagram showing the configuration of an embodiment of an object shape fluorescence measuring device using the irradiation optical system shown in FIG. 3.

An incident parallel light beam 51 emitted in two axial directions from a coherent light source (not shown) enters a phase modulating optical element 52 arranged parallel to the XY plane, and is directed to an irradiated object located f away from the origin in the Z-axis direction. The light is focused on the surface 53.

The small object 54 whose shape is measured has a size on the order of several tens of micrometers, and moves approximately on a straight line of z=f in the negative direction of the Y axis. Scattered light from these small objects 54 is detected by a detector 55. The output signal of the detector 55 is
The signal is taken into the signal processing device 56 and becomes data indicating the shape.

Now, when a light beam from a small object 54 with a size on the order of several tens of micrometers is irradiated, strong scattered light is generated in a specific direction depending on the size. If the intensity of this scattered light can be measured accurately, the size of a small object can be accurately measured.

However, if the movement of the small object is slightly displaced in the X-axis direction during measurement, and the irradiated light has a distribution of strength in the X-axis direction, the scattered light will also be affected by this, making it difficult to measure the shape of the small object. An error had occurred.

In contrast, in this embodiment using the phase modulation optical element shown in Fig. 3, the distribution of light intensity in the X-axis direction within the irradiated surface is very uniform, so that small objects can Even if the small object is displaced in the X-axis direction, the influence of the small object on the measured value is very small and can be virtually ignored.

In addition, in the object shape measuring device shown in Fig. 5, by including a fluorescent substance that is adsorbed on a certain object a among small objects, the object a can be quantified based on the size of the fluorescence generated when it is irradiated. It can be measured indirectly.

Also in this case, when the irradiation optical system shown in FIG. 3 is used, changes in fluorescence intensity due to changes in the position of the object in the X-axis direction are reduced compared to the conventional system. Therefore, the accuracy of measuring intracellular fluorescent objects increases.

FIG. 6(a) is a diagram showing the structure of an embodiment of a phase modulation optical element that uses both the hologram diffraction effect and the acousto-optic effect. This optical element consists of the optical element shown in FIG. 3(a), piezoelectric materials 61, 62 such as piezoelectric ceramics attached to the surface parallel to the yz plane, and these piezoelectric materials 61, 62. and high-frequency power sources 63 and 64 for supplying high-frequency signals.

When a high frequency electric field on the order of several MHz is applied to the piezoelectric material 62, a longitudinal wave propagates through the glass material 65 in the negative direction of the Y axis. Since longitudinal waves are compressional waves, glass material 6
5 to cause a change in the refractive index to produce a phase modulation type grating 66. The incident light beam is diffracted and deflected by this grating 66.

λ is the wavelength of the incident light flux. , the frequency of the applied electric field is f.

When the velocity of the longitudinal wave in the medium, ie, the glass material 65, is V, the deflection angle θ is expressed by equation (8).

θ=λ. f/V・・・・・・(
8) In this way, since O changes depending on the frequency of the applied electric field, the position of the focal point from the Z axis can be changed.

The same can be said of the piezoelectric material 61.

Therefore, the phase modulating optical element has an applied electric field vx, vy
By changing the frequencies fx and fy, the focal point can be moved within a plane parallel to the XY plane.

FIG. 7 is a diagram showing an embodiment of an object tracking type object shape measuring device using the phase modulation optical element shown in FIG. 6. This object shape measuring device includes an irradiation optical system 72 employing a phase 19-modulation optical element shown in FIG. 6, and a small object 74.
a detector 75 for scattered light from the detector 75, an amplifier 76 for the detected signal, an integrator 77 for integrating the amplified signal, and a trigger generator 78 for generating a trigger signal based on the amplified signal.
It consists of a variable frequency oscillator 79 that receives the trigger signal and outputs a signal on the order of several MHz.

When the small object 74 enters the illuminated surface, it emits scattered light or fluorescence. This light is detected by detector 75. The detection signal is sent from amplifier 76 to trigger generator 78 to generate a trigger signal. In response to this trigger signal, variable frequency oscillator 79 increases the oscillation frequency. The higher the frequency applied to the irradiation optical system, the larger the deflection angle of the irradiation light, which means that the irradiation light can follow a moving object for a longer time. Therefore, it is possible to increase the integration time for each small object in the integrator 77 in the signal processing system that actually obtains the piece information, and it is possible to increase the SIN ratio of the object information.

In particular, even when a fluorescent substance with low fluorescence efficiency is used, the measurement of the shape of an object and the substance inside the object can be made with high accuracy due to fluorescence.

FIG. 8 is a diagram showing an assembly apparatus for a phase modulation optical element.

This assembly device connects a plurality of phase modulating elements 82 to an incident light beam 8.
The image sensor 83 is placed on one optical path and receives the light beam that has passed through the phase modulation element 82, and an image processing device that processes the signal from the image sensor 83 and displays a light intensity profile and the like.

In order to assemble a plurality of phase modulation elements 82 and obtain a phase modulation optical element with desired characteristics, the angles and distances between the phase modulation elements 82 may be adjusted and fixed while watching the monitor of the image processing device.

In the embodiment shown in FIG. 3, a phase modulating optical element made of a linear grating phase modulating element is shown, but it can also be constructed from a bulk optical element having two aspherical surfaces 91 and 92 as shown in FIG.

Furthermore, as shown in FIG. 10, a phase modulation optical element in which the linear grating used in FIG. 3 is blazed may be used. In this case, since the -order diffraction direction is clear, it is possible to reduce high-order diffraction waves.

In addition, it is possible to use a hologram or a blazed hologram.

FIG. 11 is a diagram showing an embodiment of the irradiation optical system according to the present invention having three irradiated surfaces. The coherent light source 2, the phase modulating optical elements 40 to 4e, and the irradiated surfaces 6a to 6c are the same as the coherent light source 2, the phase modulating optical elements, and the irradiated surface of the basic embodiment shown in FIG. 3, respectively.

The phase modulation element 4f converts the incident light beam into first order and zero order.

It is a linear grating that separates into -1st order diffraction waves.

In the phase modulation elements 4a and 4b, the light flux emitted from the phase modulation element 4f is the phase modulation element 4c, respectively.

It has a function of deflecting the light so as to be incident perpendicularly to 4e, and is made of, for example, a hologram element such as a linear grating or a refractive optical element such as a prism.

According to this embodiment, a plurality of illuminated surfaces can be illuminated with a light beam from one coherent light source.

In this case, since the conventional transmittance distribution filter, which inevitably causes light attenuation, is not used, the utilization efficiency of the luminous flux does not decrease.

FIG. 12 is a diagram showing an embodiment using an optical element in which the phase modulating optical element of the first embodiment is integrated.

The integrated phase modulating optical element 23 of this embodiment has the linear gratings 4f and 4a described above on both sides of the glass plate 21.
, 4b, and linear gratings 4c, 4d', 4e are formed on one side of the glass plate 22, and the glass plates 21 and 22
These are integrated to form a phase modulation optical element.

Integration in this manner simplifies component processing and leads to a more compact irradiation optical system as a whole.

In the embodiments shown in FIGS. 11 and 12, the number of irradiated surfaces is three, but it goes without saying that the number of irradiated surfaces may be two or even larger.

〔Effect of the invention〕

According to the present invention, an incident light beam having a coherent and horizontally center-symmetrical light intensity distribution is divided centrally symmetrically in the longitudinal direction of the irradiated surface, and the light beams of each division are divided into 23- sections on the irradiated surface in the longitudinal direction. Since a phase modulating optical element is used which is superimposed on the irradiated surface, the light intensity distribution in the longitudinal direction of the irradiated surface can be made extremely uniform.

Therefore, for example, even if the position of the small object in the longitudinal direction changes in the cell analyzer, there is no fluctuation in the scattered light from the small object, and the shape and size of the cell can be accurately measured.

Furthermore, since no transmittance distribution type filter is used to make the light intensity uniform in the longitudinal direction of the irradiated surface, the efficiency of using the luminous flux is good.

Furthermore, since it is possible to adopt means for causing the focal point of the light beam to follow a small object by applying a high-frequency electric field, the accuracy of the integration result of the detection signal is increased.

Particularly, when detecting fluorescence by adsorbing a fluorescent substance of a small object to be measured, the integration time can be increased and measurement results with a good S/N ratio can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the irradiation optical system employing the phase modulation optical element according to the present invention, and FIG. 2 is a diagram illustrating the function of the phase modulation optical element of the embodiment shown in FIG. is a diagram more specifically explaining the characteristics of a phase modulation optical element that irradiates one irradiated surface, Figure 4 is a diagram showing the relationship between the position on the irradiated surface and the light intensity distribution, and Figure 5 is the main figure. FIG. 6 is a diagram showing the configuration of an embodiment of the object shape fluorescence measuring device according to the invention, FIG. A diagram showing an example of an object tracking type object shape measuring device using the phase modulation optical element shown in the figure, Figure 8 is a diagram showing an assembly apparatus for the phase modulation optical element, and Figure 9 is a diagram showing a bulk type phase modulation optical element. 10 is a diagram showing a phase modulation optical element using a blazed grating. FIG. 11 is a diagram showing an embodiment of the irradiation optical system according to the present invention having three irradiated surfaces. FIG. 12 shows an embodiment of the irradiation optical system according to the invention using integrated optical elements. 2... Coherent light source, 4... Phase modulation (optical) element, 6... Irradiated surface, Work 2... Optical element, 21.22 ・Glass plate, 23...
・Integrated optical element, 31...Incoming light flux, ↓...Incoming parallel light flux, 52...Optical element, 3...Irradiated surface, 5
4...Small object, 55...Detector, 6...Signal processing device, 61.62...Piezoelectric material, 3.64...High frequency power supply, 65...Glass material, 6... ...Phase modulation grating, 1...Incoming parallel light flux, 72...Irradiation optical system, 4...
・Small object, 75...Detector, 76...Amplifier, 7...
- Integrator, 78... Trigger generator, 9... Frequency variable oscillator, 81... Incident light flux, 2... Phase modulation element, 83... Image sensor, 4... Image processing device, 9
1.92...Aspherical surface, 01...Blaze type grating.

Claims (1)

[Claims] 1. In an irradiation optical system that illuminates a horizontally long irradiated surface with a light beam emitted from at least one light source with an axially symmetrical intensity distribution, the light beam is directed in the longitudinal direction of the irradiated surface. 1. An irradiation optical system comprising a phase modulation optical element that divides the light beam into centrally symmetrical sections and superimposes the light beams of each section on the irradiated surface in the longitudinal direction. 2. Due to the light beam from a coherent light source whose Z component of the XYZ orthogonal coordinate system is in a negative region, it is parallel to the XY plane and symmetrical to the XZ plane and YZ plane, and the width in the X axis direction is DX,
In the irradiation optical system that illuminates the irradiated surface whose width in the Y-axis direction is DY and is located at the Z-axis coordinate f (f>0), it is arranged approximately at the origin of the XYZ orthogonal coordinate system, and the number of divisions is set to N (N ≧2), when the width of the incident light beam in the X-axis direction is (DX×N), the incident light beam is obtained by dividing the irradiated surface into N equal parts symmetrically about the YZ plane and moving the wavefront of each section in parallel on the irradiated surface. 1. An irradiation optical system comprising a phase modulation optical element that deflects the light in the positive and negative directions of the Y-axis and focuses the light on a surface to be irradiated. 3. The irradiation optical system according to claim 1 or 2, further comprising an acousto-optic element that controls the amplitude and phase modulation function of the phase modulation optical element and changes the position of the light beam on a plane orthogonal to the incident light beam. An irradiation optical system featuring: 4. The irradiation optical system according to any one of claims 1 to 3, wherein the irradiation optical system includes a number of the phase modulating optical elements corresponding to the plurality of irradiated surfaces and a light beam from the light source. An irradiation optical system comprising: an optical element divided into each phase modulation optical element. 5. The irradiation optical system according to claim 4, comprising a composite element in which at least a part of the optical element is integrated in at least one direction from the light source to the irradiated surface and in a direction perpendicular to this direction. An irradiation optical system characterized by: 6. The irradiation optical system according to any one of claims 2 to 5, which irradiates an object moving approximately in the Y-axis direction near X=0 and Z=f of the XYZ orthogonal coordinate system, and scattering caused by the irradiation. An object shape measuring device comprising a detection system that detects light and a signal processing system that obtains data such as the shape of the object based on a detection signal from the detection system. 7. The object shape fluorescence measuring device according to claim 6, wherein the detection system includes a detector that detects scattered light and fluorescence generated by irradiation. 8. In an irradiation optical system that illuminates a horizontally long irradiated surface with a light beam emitted from at least one light source with an axially symmetrical intensity distribution, the light beam is directed in the longitudinal direction of the irradiated surface, comprising an aspherical bulk lens. A phase modulation optical element that splits the light beam into each section symmetrically with respect to the center and superimposes the light beams of each section in the longitudinal direction on the irradiated surface. 9. In an irradiation optical system that illuminates a horizontally long irradiated surface with a light beam emitted from at least one light source with an axially symmetrical intensity distribution, the illumination optical system is comprised of a blazed grating and directs the light beam in the longitudinal direction of the irradiated surface. A phase modulation optical element that divides the light beam into centrally symmetrical sections and superimposes the light beams of each section in the longitudinal direction on the irradiated surface. 10. An irradiation optical system that illuminates a horizontally long irradiated surface with a light beam emitted from at least one light source with an axially symmetrical intensity distribution, comprising a hologram, the light beam being centered in the longitudinal direction of the irradiated surface. A phase modulating optical element that divides the light beam symmetrically and overlaps the light beams of each section in the longitudinal direction on the irradiated surface. 11. An irradiation optical system that illuminates a horizontally long irradiated surface with a light beam emitted from at least one light source with an axially symmetrical intensity distribution, comprising a blazed hologram, and which directs the light beam in the longitudinal direction of the irradiated surface. A phase modulation optical element that splits the light beam into each section symmetrically with respect to the center and superimposes the light beams of each section in the longitudinal direction on the irradiated surface. 12. The phase modulation optical element according to any one of claims 8 to 11, further comprising: an acoustic device that controls the amplitude and phase modulation function of the phase modulation optical element to change the position of the light beam on a plane orthogonal to the incident light beam; A phase modulation optical element characterized by comprising an optical element. 13. The irradiation optical system or phase modulating optical element assembly apparatus according to any one of claims 1 to 12, comprising: an image sensor disposed at a position of the irradiated surface of the phase modulating optical element; and the image sensor. an image processing device that processes signals from the irradiated light beam and displays the intensity profile of the irradiated light beam on the irradiated surface; and means for adjusting one position.