JP6032521B2 - Illumination device, projection device and exposure device - Google Patents

Description

  The present invention relates to an illumination device, a projection device, and an exposure device that use coherent light as illumination light.

  Among lighting devices, LEDs and laser diodes (LDs) have the advantage of being small, low power consumption, and excellent color reproducibility, and also have good compatibility as light sources for various diffractive optical elements such as holograms. (See Patent Documents 1 and 2).

  Further, Patent Document 3 converts the wavelength of a laser beam emitted from a laser light source to generate laser beams having a plurality of wavelengths, irradiates an object with these laser beams, and forms an interference pattern on a photosensitive substrate. A technique for recording is disclosed.

Japanese Patent Laid-Open No. 6-208089 JP-A-6-301322 JP 11-119634 A

  However, LEDs and LD tend to have a large variation in center wavelength due to individual differences, and it is known that the center wavelength changes depending on the output energy of the laser beam emitted from the LED or LD. Furthermore, the center wavelength of the LED or LD varies depending on the temperature.

  For this reason, conventionally, a light source for an LED or LD is provided with a mechanism for compensating for a shift in the center wavelength, an LED or LD is manufactured from an expensive material that is unlikely to shift in the center wavelength, or a shift in the center wavelength is performed. Various measures were taken, such as adopting various optical components that would not be a problem. For this reason, the problem that the whole apparatus became large sized and the apparatus cost increased occurred.

  On the other hand, when an illumination device is configured using a laser beam emitted from an LED, LD, or the like, a diffractive optical element for diffracting the laser beam and irradiating the illuminated area is required. Since the diffraction center wavelength of the element also changes depending on the temperature, it is not sufficient to adjust the temperature of the light source alone. Even if the center wavelength of the laser beam emitted from the light source is adjusted, the diffraction of the diffractive optical element Since the characteristics change with temperature, the illumination quality of the illuminated area varies with temperature.

  The present invention has been made in consideration of this type of problem, and in the case where coherent light is used as illumination light, the illumination apparatus, projection apparatus, and exposure apparatus in which illumination quality is not affected by temperature. Is to provide.

In order to solve the above-described problem, in one aspect of the present invention, a diffractive optical element capable of diffusing the coherent light incident on each point of the incident surface over a predetermined region;
An irradiation device for irradiating coherent light toward the incident surface of the diffractive optical element;
A first temperature measurement unit for measuring the temperature of the irradiation device;
A second temperature measurement unit for measuring the temperature of the diffractive optical element;
A diffractive wavelength adjuster that adjusts the diffraction center wavelength of the diffractive optical element according to a shift in the center wavelength of coherent light emitted by the irradiation device, based on the temperature measurement results of the first and second temperature measurement units; A lighting device characterized by comprising: is applied.

  According to the present invention, when coherent light is used as illumination light, the diffraction center wavelength of the diffractive optical element can be adjusted so that the illumination quality is not affected by temperature.

The figure which shows schematic structure of the illuminating device 40 which concerns on the 1st Embodiment of this invention. FIG. 3 is a block diagram illustrating an example of an internal configuration of a diffraction wavelength adjuster 3. The figure which shows an example which graphed the 2nd table. The figure which shows an example which added the light source wavelength regulator 8 which adjusts the center wavelength of the coherent light from the laser light source 61 to the illuminating device 40 of FIG. The figure explaining a mode that the image of a scattering plate is formed in the hologram recording medium 55 as an interference fringe. The figure explaining a mode that the image of a scattering plate is reproduced | regenerated using the interference fringe formed in the hologram recording medium 55 obtained through the exposure process of FIG. The figure which shows the example which added the scanning device 65 to the irradiation apparatus 60 in the illuminating device 40 of FIG. The figure explaining the scanning path | route of the scanning device 65. FIG. The figure which shows schematic structure of the projection apparatus 20 which concerns on the 2nd Embodiment of this invention. The figure which shows schematic structure of the exposure apparatus 10 which concerns on the 2nd Embodiment of this invention. The figure which shows schematic structure of the example of 1 application of FIG. The figure which shows the example which a mirror device can rotate also centering on 2nd rotation axis RA2 which cross | intersects 1st rotation axis RA1.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings attached to the present specification, for convenience of illustration and understanding, the scale, the vertical / horizontal dimensional ratio, and the like are appropriately changed or exaggerated from those of the actual ones.

(First embodiment)
The first embodiment described below is an illumination device using a hologram recording medium as a diffractive optical element, and adjusts the diffraction center wavelength of the hologram recording medium in accordance with the center wavelength of coherent light emitted by a laser light source. Is.

  FIG. 1 is a diagram showing a schematic configuration of an illumination device 40 according to the first embodiment of the present invention. 1 includes a hologram recording medium 55, an irradiation device 60, a first temperature measurement unit 1, a second temperature measurement unit 2, and a diffraction wavelength adjuster 3.

  The hologram recording medium 55 is a diffractive optical element 50 capable of diffusing the coherent light incident on each point of the incident surface so as to overlap at least a predetermined region (hereinafter referred to as an illuminated region LZ). Interference fringes are formed on the incident surface on which the coherent light is incident, and the coherent light is diffracted into diffused light by the interference fringes. This diffused light reproduces the diffraction image recorded on the hologram recording medium 55 in the illuminated area LZ. Details of the hologram recording medium 55 will be described later.

  The irradiation device 60 includes a laser light source 61 that emits coherent light toward the incident surface of the hologram recording medium 55. The laser light source 61 is, for example, an LED or a laser diode (LD). Since the laser light source 61 has a narrow wavelength band, it can only illuminate a single color. For example, a plurality of laser light sources 61 having different wavelength bands can emit light simultaneously or in a time division manner to illuminate the illuminated area LZ with various colors. It is also possible to do. In the following, for simplification, an example in which a single laser light source 61 is used to illuminate with a single color will be described.

  The first temperature measurement unit 1 measures the temperature of the laser light source 61 or the vicinity thereof. The second temperature measurement unit 2 measures the temperature of the hologram recording medium 55 or the vicinity thereof. The 1st temperature measurement part 1 and the 2nd temperature measurement part 2 are comprised using the temperature sensor using a semiconductor temperature sensor, for example. A thermocouple may be used as the sensor, or a radiation thermometer may be used.

  The diffraction wavelength adjuster 3 adjusts the diffraction center wavelength of the diffractive optical element 50 according to the shift of the center wavelength of the coherent light from the laser light source 61 based on the measurement results of the first and second temperature measuring units 1 and 2. To do.

  FIG. 2 is a block diagram showing an example of the internal configuration of the diffraction wavelength adjuster 3. The diffraction wavelength adjuster 3 in FIG. 2 includes a first table storage unit 11, a second table storage unit 12, and a temperature adjustment unit 13.

  The first table storage unit 11 stores a first table indicating a correspondence relationship between the temperature of the laser light source 61 and the shift amount of the center wavelength of the coherent light from the laser light source 61.

  The second table storage unit 12 stores a second table indicating the correspondence between the temperature of the hologram recording medium 55 and the shift amount of the diffraction center wavelength of the hologram recording medium 55.

  The temperature adjustment unit 13 refers to the first and second tables based on the temperature measurement results of the first and second temperature measurement units 1 and 2 so as to match the center wavelength of the coherent light from the laser light source 61. The diffraction center wavelength of the diffractive optical element 50 is adjusted. More specifically, the temperature adjustment unit 13 variably controls the temperature of the diffractive optical element 50 to adjust the diffraction center wavelength of the diffractive optical element 50.

  It is known that the center wavelength of the coherent light from the laser light source 61 varies depending on individual differences among the individual laser light sources 61, the output energy of the coherent light from the laser light source 61, and the temperature of the laser light source 61.

  For this reason, at the stage of assembling the illumination device 40 of FIG. 1, the temperature of the laser light source 61 is varied for each illumination device 40, the center wavelength of the coherent light is measured, and the measurement result is stored in the first table. Register. When the output energy of the coherent light from the laser light source 61 is varied, the correspondence between the output energy and the center wavelength of the coherent light is also measured and registered in the first table.

  If such a first table is created in advance and stored in the first table storage unit 11, when the temperature of the laser light source 61 is subsequently measured by the first temperature measurement unit 1, the first table is referred to. By doing so, the center wavelength of the coherent light from the laser light source 61 can be estimated accurately.

  Similarly, when the illumination device 40 of FIG. 1 is assembled, the temperature of the hologram recording medium 55 is changed variously, the diffraction center wavelength of the hologram recording medium 55 is measured, and the measurement result is registered in the second table. deep.

  FIG. 3 is a graph showing an example of the second table, in which the horizontal axis indicates the temperature of the hologram recording medium 55 and the vertical axis indicates the diffraction center wavelength of the hologram recording medium 55. As shown in FIG. 3, it can be seen that when the temperature of the hologram recording medium 55 changes, the diffraction center wavelength shifts, and the diffraction center wavelength tends to increase as the temperature increases.

  In the graph of FIG. 3, a DPSS laser (center wavelength: 532 nm) is used as the laser light source 61, and the photopolymer disclosed in Example 1 of JP-A-6-301322 is used as the hologram recording medium 55.

  Note that FIG. 3 is merely an example, and depending on the material, film thickness, and the like of the hologram recording medium 55, different characteristics may be obtained, but in any case, the diffraction center wavelength of the hologram recording medium 55 depends on the temperature. fluctuate.

  If the second table is prepared in advance, the diffraction center wavelength of the hologram recording medium 55 is accurately estimated by referring to the second table based on the temperature of the hologram recording medium 55 measured by the second temperature measuring unit 2. it can.

  The temperature adjustment unit 13 in the diffraction wavelength adjuster 3 obtains the center wavelength of the coherent light from the laser light source 61 from the first table based on the temperature of the laser light source 61 measured by the first temperature measurement unit 1, and the second table While referring to the table, the diffraction center wavelength of the hologram recording medium 55 is changed so as to match the center wavelength of the acquired coherent light. In order to change the diffraction center wavelength of the hologram recording medium 55, as can be seen from FIG. 3, the temperature of the hologram recording medium 55 may be changed. Therefore, the temperature adjustment unit 13 adjusts the temperature of the hologram recording medium 55 according to the center wavelength of the coherent light from the laser light source 61 to change the diffraction center wavelength of the hologram recording medium 55. At this time, referring to the second table based on the temperature of the hologram recording medium 55 measured by the second temperature measuring unit 2, the temperature of the hologram recording medium 55 is adjusted so as to obtain a desired diffraction center wavelength.

  Thereby, the center wavelength of the coherent light from the laser light source 61 coincides with the diffraction center wavelength of the hologram recording medium 55, and the coherent light incident on the hologram recording medium 55 from the laser light source 61 is diffused as originally designed. The illuminated area LZ is illuminated.

  It is desirable that the temperature adjusting unit 13 in the diffraction wavelength adjuster 3 is disposed in close contact so as to be in direct contact with the hologram recording medium 55. This is because the temperature of the hologram recording medium 55 can be accurately measured and the adjustment accuracy of the diffraction center wavelength of the hologram recording medium 55 is improved. For example, when cooling, it is impossible to perform precise temperature adjustment by separating the temperature adjusting unit 13 from the hologram recording medium 55 and performing indirect cooling such as air cooling. It is desirable to adjust the temperature using water cooling, a Peltier device, or the like.

  In the example of FIG. 1, the diffraction wavelength adjuster 3 is brought into contact with the hologram recording medium 55, but the temperature of the hologram recording medium 55 is not necessarily in close contact with the hologram recording medium 55 by the temperature adjusting unit 13 in the diffraction wavelength adjuster 3. It is possible to adjust without making it. For example, the temperature of the hologram recording medium 55 can be indirectly adjusted by interposing air between the hologram recording medium 55 and the temperature adjusting unit 13 and heating or cooling the air. More specifically, when the temperature change cannot be controlled by direct contact, such as when heat is generated due to the arrangement of the light absorption layer even though it is high output light, it is necessary to adjust the temperature while transmitting light, and the indirect described above Temperature adjustment is effective.

  Of course, when air is interposed, the heat propagation efficiency is lower than when the air is in close contact with each other. However, if the temperature adjustment unit 13 cannot be disposed in close contact with the hologram recording medium 55 due to the optical arrangement of the illumination device 40, both are physically connected. The temperature of the hologram recording medium 55 may be adjusted by warm air or cold air by a fan or the like. For example, when the transmissive hologram recording medium 55 is used, the opposing surfaces serve as optical paths for coherent light, and the temperature adjustment unit 13 cannot be disposed in close contact with both surfaces. Just do it.

  On the other hand, when the temperature adjusting unit 13 is disposed in close contact with the hologram recording medium 55, heating is performed using electric resistance heat, hot water circulation, a Peltier element, or the like, and cooling is performed using refrigerant vaporization heat, cold water circulation, a Peltier element, or the like. Good.

  When the transmission type hologram recording medium 55 is used, the hologram recording medium 55 may be heated or cooled by closely placing the temperature adjusting unit 13 on the side surface of the hologram recording medium 55. In this case, when it is desired to suppress the temperature variation in the hologram recording medium 55, the temperature adjusting unit 13 may be disposed on each of the two side surfaces or the four side surfaces facing each other.

  Although the illumination device 40 in FIG. 1 does not include means for adjusting the center wavelength of coherent light from the laser light source 61, such means may be provided.

  FIG. 4 is a diagram showing an example in which a light source wavelength adjuster 8 for adjusting the center wavelength of coherent light from the laser light source 61 is added to the illumination device 40 of FIG. The light source wavelength adjuster 8 in FIG. 4 shifts the center wavelength in the reverse direction by the amount that the center wavelength of the coherent light from the laser light source 61 is shifted by the temperature change of the laser light source 61 measured by the first temperature measurement unit 1. To compensate for the shift in the center wavelength.

  The light source wavelength adjuster 8 includes a third table indicating the correspondence between the temperature of the laser light source 61 and the center wavelength of the coherent light, and is based on the temperature of the laser light source 61 measured by the first temperature measurement unit 1. By referring to the third table, the current center wavelength of the coherent light is acquired, and the wavelength control is performed so that the original center wavelength is obtained. Although the specific method of wavelength control is not ask | required, you may adjust the center wavelength of coherent light by adjusting the temperature of the laser light source 61 similarly to the hologram recording medium 55, for example. Therefore, the light source wavelength adjuster 8 needs to be disposed in close contact with the laser light source 61 or in the vicinity of the laser light source 61.

  The diffraction wavelength adjuster 3 in FIG. 4 has the same internal configuration as that in FIG. 2, but the first table is created taking into consideration that the light source wavelength adjuster 8 adjusts the center wavelength of the coherent light. Is done.

  As described above, since the wavelength of the coherent light emitted from the laser light source 61 can be adjusted by providing the light source wavelength adjuster 8, it is possible to control such that the wavelength of the coherent light does not change with temperature. Accordingly, since the wavelength of the coherent light from the laser light source 61 does not vary with temperature, the adjustment accuracy of the diffraction center wavelength in the diffraction wavelength adjuster 3 is also improved.

  The hologram recording medium 55 constituting the diffractive optical element 50 can receive the coherent light emitted from the irradiation device 60 as the reproduction illumination light La and diffract the coherent light with high efficiency. In particular, the hologram recording medium 55 diffracts the coherent light incident on each minute position, in other words, each minute area to be called each point, thereby diffracting the image recorded on the hologram recording medium 55 in the illuminated area LZ. 5 can be reproduced.

  The coherent light incident on each position of the hologram recording medium 55 from the irradiation device 60 is diffracted by the hologram recording medium 55 and illuminates a predetermined region that overlaps at least partly. In particular, in the embodiment described here, the coherent light incident on each position of the hologram recording medium 55 from the irradiation device 60 is diffracted by the hologram recording medium 55 to illuminate the same illuminated region LZ. .

  In the illustrated example, a reflection type volume hologram using a photopolymer is used as the hologram recording medium 55 that enables the diffraction action of such coherent light. FIG. 5 is a diagram for explaining how the image of the scattering plate is formed as interference fringes on the hologram recording medium 55. Here, the scattering plate 6 is a reference member that scatters light, and a specific form of the reference member is not limited.

  As shown in FIG. 5, the hologram recording medium 55 is manufactured using the scattered light from the actual scattering plate 6 as the object light Lo. FIG. 5 shows a state where the photosensitive light 58 having photosensitivity that forms the hologram recording medium 55 is exposed to the reference light Lr and the object light Lo made of coherent light having coherence with each other. Has been.

  As the reference light Lr, for example, laser light from a laser light source 61 that oscillates laser light in a specific wavelength region is used. The reference light Lr passes through the condensing element 7 made of a lens and enters the hologram photosensitive material 58. In the example shown in FIG. 5, the laser light for forming the reference light Lr is incident on the condensing element 7 as a parallel light beam parallel to the optical axis of the condensing element 7. The reference light Lr passes through the condensing element 7, so that it is shaped (converted) into a convergent light beam from the parallel light beam so far, and is incident on the hologram photosensitive material 58. At this time, the focal position FP of the convergent light beam Lr is at a position past the hologram photosensitive material 58. That is, the hologram photosensitive material 58 is disposed between the light condensing element 7 and the focal position FP of the convergent light beam Lr condensed by the light condensing element 7.

  Next, the object light Lo is incident on the hologram photosensitive material 58 as scattered light from a scattering plate 6 made of, for example, opal glass. In the example of FIG. 5, the hologram recording medium 55 to be manufactured is a reflection type, and the object light Lo is incident on the hologram photosensitive material 58 from the surface opposite to the reference light Lr. The object light Lo is premised on having coherency with the reference light Lr. Therefore, for example, the laser light oscillated from the same laser light source 61 can be divided, and one of the divided light can be used as the reference light Lr and the other can be used as the object light Lo.

  In the example shown in FIG. 5, a parallel light beam parallel to the normal direction to the plate surface of the scattering plate 6 is incident on the scattering plate 6 and scattered, and the scattered light transmitted through the scattering plate 6 is the object light Lo. The light enters the hologram photosensitive material 58. According to this method, when an isotropic scattering plate that is usually available at a low cost is used as the scattering plate 6, the object light Lo from the scattering plate 6 is incident on the hologram photosensitive material 58 with a substantially uniform light amount distribution. Is possible. Further, according to this method, although depending on the degree of scattering by the scattering plate 6, the object light Lo is incident on each position of the hologram photosensitive material 58 with a substantially uniform light amount from the entire area of the exit surface 6 a of the scattering plate 6. It becomes easy. In such a case, the light incident on each position of the obtained hologram recording medium 55 reproduces the image 5 of the scattering plate 6 with the same brightness, and the reproduced image of the scattering plate 6. It can be realized that 5 is observed with approximately uniform brightness.

  As described above, when the hologram recording material 58 is exposed to the reference light Lr and the object light Lo, an interference fringe formed by the interference of the reference light Lr and the object light Lo is generated. It is recorded on the hologram recording material 58 as a pattern (in the case of a volume hologram, for example, a refractive index modulation pattern). Thereafter, appropriate post-processing corresponding to the type of the hologram recording material 58 is performed, and the hologram recording material 55 is obtained.

  FIG. 6 is a diagram for explaining how the image of the scattering plate is reproduced using the interference fringes formed on the hologram recording medium 55 obtained through the exposure process of FIG. As shown in FIG. 6, the hologram recording medium 55 formed of the hologram photosensitive material 58 of FIG. 5 is light having the same wavelength as the laser beam used in the exposure process, and the optical path of the reference light Lr in the exposure process The light traveling in the opposite direction satisfies the Bragg condition. That is, as shown in FIG. 6, the reference point SP positioned with respect to the hologram recording medium 55 so as to have the same positional relationship as the relative position of the focal point FP with respect to the hologram photosensitive material 58 during the exposure process (see FIG. 5). The divergent light beam that diverges from the light beam and has the same wavelength as the reference light Lr during the exposure process is diffracted by the hologram recording medium 55 as the reproduction illumination light La, and is relative to the hologram photosensitive material 58 during the exposure process. The reproduced image 5 of the scattering plate 6 is generated at a specific position with respect to the hologram recording medium 55 that has the same positional relationship as the position (see FIG. 5).

  At this time, the reproduction light (light obtained by diffracting the reproduction illumination light La by the hologram recording medium 55) Lb that generates the reproduction image 5 of the scattering plate 6 travels from the scattering plate 6 toward the hologram photosensitive material 58 during the exposure process. Each point of the image 5 of the scattering plate 6 is reproduced as light traveling in the opposite direction along the optical path of the object light Lo that has been emitted. Here, as shown in FIG. 5, the scattered light Lo emitted from each position on the exit surface 6 a of the scattering plate 6 during the exposure process is diffused so as to enter almost the entire region of the hologram photosensitive material 58. ,It has spread. That is, the object light Lo from the entire area of the exit surface 6 a of the scattering plate 6 is incident on each position on the hologram photosensitive material 58, and as a result, information on the entire exit surface 6 a is placed on each position of the hologram recording medium 55. Each is recorded. For this reason, each light which forms the divergent light beam from the reference point SP functioning as the reproduction illumination light La shown in FIG. 6 is incident on each position of the hologram recording medium 55 independently and has the same contour. The image 5 of the scattering plate 6 can be reproduced at the same position, that is, the illuminated region LZ.

  When a laser is used as a light source, speckles are generated due to high coherence. A speckle is a speckled pattern that appears when a scattering surface is irradiated with laser light or other coherent light. When it appears on a screen, it is observed as speckled brightness irregularities (brightness irregularities). It becomes a factor having a physiological adverse effect on the person. The reason why speckles occur when coherent light is used is that coherent light reflected by each part of a scattering reflection surface such as a screen interferes with each other because of its extremely high coherence. .

  In order to avoid this type of speckle, the irradiation device 60 may be provided with a scanning device 65 that scans the surface of the diffractive optical element 50 with coherent light emitted from the laser light source 61. By providing the scanning device 65, the coherent light from the laser light source 61 scans the recording surface of the hologram recording medium 55, and the direction in which the coherent light diffused by the hologram recording medium 55 is incident on the illuminated region LZ is also elapsed. Therefore, the speckle pattern generated on the illuminated area LZ is also greatly changed, and the uncorrelated speckle pattern is superimposed, so that the speckle is not visually recognized.

  FIG. 7 is a diagram showing an example in which a scanning device 65 is added to the irradiation device 60 in the illumination device 40 of FIG. The scanning device 65 changes the traveling direction of the coherent light with time, and directs it in various directions so that the traveling direction of the coherent light is not constant. As a result, the coherent light whose traveling direction is changed by the scanning device 65 scans the incident surface of the hologram recording medium 55 of the diffractive optical element 50.

  FIG. 8 is a diagram for explaining the scanning path of the scanning device 65.

  The scanning device 65 according to the present embodiment includes a reflecting device 66 having a reflecting surface 66a that can be rotated about one axis RA1. The reflection device 66 includes a mirror device having a mirror as a reflection surface 66a that can be rotated about one axis RA1. This mirror device 66 changes the traveling direction of coherent light from the laser light source 61 by changing the orientation of the mirror 66a. At this time, as shown in FIG. 8, the mirror device 66 generally receives coherent light from the laser light source 61 at the reference point SP.

  The coherent light whose traveling direction is finally adjusted by the mirror device 66 is incident on the hologram recording medium 55 of the diffractive optical element 50 as reproduction illumination light La (see FIG. 6) that can form one light beam diverging from the reference point SP. Can do. As a result, the coherent light from the irradiation device 60 scans on the hologram recording medium 55, and the image of the scattering plate 6 in which the coherent light incident on each position on the hologram recording medium 55 has the same contour. 5 is reproduced at the same position, that is, the illuminated area LZ.

  As shown in FIG. 8, the reflection device 66 is configured to rotate the mirror 66a along one axis RA1. In the example shown in FIG. 8, the rotation axis RA1 of the mirror 66a is the XY coordinate system defined on the plate surface of the hologram recording medium 55, that is, the XY plane is parallel to the plate surface of the hologram recording medium 55. It extends parallel to the Y axis of the XY coordinate system. Then, since the mirror 66a rotates around the axis line RA1 parallel to the Y axis of the XY coordinate system defined on the plate surface of the hologram recording medium 55, the coherent light from the irradiation device 60 is directed to the diffractive optical element 50. The incident point IP reciprocates in a direction parallel to the X axis of the XY coordinate system defined on the plate surface of the hologram recording medium 55. That is, in the example shown in FIG. 8, the irradiation device 60 irradiates the diffractive optical element 50 with coherent light so that the coherent light scans on the hologram recording medium 55 along a linear path.

  As described above, the scanning device 65 configured by the mirror device 66 or the like is a member that can rotate at least around the axis line RA1, and is configured by using, for example, MEMS. The scanning device 65 periodically rotates, but in applications such as a liquid crystal display device that is directly observed by humans, it is 1/30 seconds per cycle, which is more coherent at a higher speed depending on the type of screen to be displayed. If it can scan with light, there will be no restriction | limiting in particular in the rotation frequency.

  As a practical problem, the hologram recording material 58 may shrink when the hologram recording medium 55 is produced. In such a case, it is preferable to adjust the incident / exit angle of the coherent light irradiated from the irradiation device 60 to the diffractive optical element 50 in consideration of the shrinkage of the hologram recording material 58. Therefore, the wavelength of the coherent light generated by the coherent light source 61 does not need to be exactly the same as the wavelength of the light used in the exposure process of FIG. 5 and may be substantially the same.

  For the same reason, the traveling direction of the light incident on the hologram recording medium 55 of the diffractive optical element 50 is not limited even if it takes the exact same path as the one light beam included in the divergent light beam from the reference point SP. The image 5 can be reproduced in the illumination area LZ. Actually, in the example shown in FIG. 8, the mirror (reflection surface) 66a of the mirror device 66 constituting the scanning device 65 is inevitably deviated from the rotation axis RA1. Therefore, when the mirror 66a is rotated around the rotation axis RA1 that does not pass through the reference point SP, the light incident on the hologram recording medium 55 may not be a single light beam that forms a divergent light beam from the reference point SP. is there. However, in practice, the image 5 can be substantially reproduced by being superimposed on the illuminated region LZ by coherent light from the irradiation device 60 having the illustrated configuration.

  By the way, the scanning device 65 does not necessarily have to be a member that reflects the coherent light. Instead of reflecting, the scanning device 65 may cause the coherent light to be refracted or diffracted to scan the coherent light on the diffractive optical element 50. .

  Thus, in the first embodiment, the first table is created in advance in anticipation that the center wavelength of coherent light from the laser light source 61 changes due to individual differences of the laser light source 61, output energy, temperature, and the like. Similarly, the second table is created in advance in view of the fact that the diffraction center wavelength of the hologram recording medium 55 changes with temperature. Then, based on the temperature measurement result of the laser light source 61 and the temperature measurement result of the hologram recording medium 55, the temperature of the hologram recording medium 55 is adjusted with reference to the first and second tables. The center wavelength can be made to coincide with the center wavelength of the coherent light from the laser light source 61, and the illuminated area LZ is uniformly illuminated as designed with the coherent light that is incident on the hologram recording medium 55 and diffused regardless of the temperature. And lighting efficiency is improved.

(Second Embodiment)
In the second embodiment described below, a projection device is configured using the illumination device 40 according to the first embodiment described above.

  FIG. 9 is a diagram showing a schematic configuration of a projection apparatus 20 according to the second embodiment of the present invention. In FIG. 9, the same components as those in FIG. 7 are denoted by the same reference numerals, and different points will be mainly described below.

  9 includes a light modulator 30, a projection optical system 80, and a diffusion screen 15 in addition to the illumination device 40 of FIG.

  The light modulator 30 is disposed at a position overlapping the illuminated area LZ, generates a modulated image using illumination light in the modulated area, and guides it to the projection optical system 80.

  As the optical modulator 30, for example, a reflective microdisplay made of a micro electro mechanical systems (MEMS) element such as a DMD (digital micromirror device) can be used. The DMD is also used as the optical modulator 30 in the apparatus disclosed in Patent Document 2 described above.

  In addition, as the optical modulator 30, a reflective LCOS or a transmissive liquid crystal panel can be used.

  It is preferable that the incident surface of the light modulator 30 has the same position and the same shape and size as the illuminated region LZ where the illumination device 40 emits coherent light. In this case, it is because the coherent light from the illuminating device 40 can be utilized with high utilization efficiency for displaying the image on the diffusion screen 15.

  The projection optical system 80 that projects the modulated image generated by the light modulator 30 onto the diffusing screen 15 includes a projection lens 81 composed of a plurality of lens groups, for example, and the modulated image generated by the light modulator 30. Is refracted by the projection lens 81 and projects a modulated image on the diffusing screen 15. The size of the modulated image projected on the diffusion screen 15 can be adjusted by the diameter of the projection lens 81, the distance between the projection lens 81 and the light modulator 30, and the distance between the projection lens 81 and the diffusion screen 15. The diffusing screen 15 in FIG. 9 is a transmissive type and diffuses the projected modulated image light. The diffusing screen 15 may be a reflective type.

  Although omitted in FIG. 9, the modulated image diffused by the diffusion screen 15 is incident on a half mirror (not shown), and a part of the modulated image light diffused by the diffusion screen 15 is reflected by this half mirror. Thus, a virtual image of the modulated image may be formed, and this virtual image may be viewed by an observer through a half mirror together with external light. Thereby, a head-up display device can be realized. In this case, for example, the front windshield of the vehicle can be used as the half mirror, and the observer can view the virtual image while viewing the scenery outside the vehicle through the windshield by sitting in the driver's seat and facing forward. Alternatively, a hologram recording medium 55 or a prism may be used instead of the half mirror.

  The light modulator 30 can generate various modulated images. The light modulator 30 generates a modulated image and illuminates the modulated image in the illuminated area LZ, so that the various modulated images can be generated by the diffusion screen 15. Can be projected up.

  Also in the projection apparatus 20 according to the second embodiment, by providing the diffraction wavelength adjuster 3, the hologram recording medium can be used regardless of the individual difference, output energy, and temperature of the laser light source 61 and the temperature of the hologram recording medium 55. Since the 55 diffraction center wavelengths can coincide with the center wavelength of the coherent light from the laser light source 61, the illuminated area LZ can be illuminated uniformly, and the quality of the image displayed on the diffusion screen 15 is improved.

(Third embodiment)
In the third embodiment described below, an exposure apparatus is configured using the illumination device 40 according to the first embodiment described above.

  FIG. 10 is a view showing the schematic arrangement of an exposure apparatus 10 according to the third embodiment of the present invention. In FIG. 10, the same reference numerals are given to components common to FIG. 7, and different points will be mainly described below.

  The exposure apparatus 10 in FIG. 10 includes an optical modulator 30 in addition to the illumination apparatus 40 in FIG. The coherent light modulated by the light modulator 30 is guided to the surface of the photosensitive medium 15.

  The light modulator 30 is, for example, a transmissive or reflective reticle (mask). In this case, an optical image corresponding to the reticle pattern is formed on the surface of the photosensitive medium 15 and can be used as the exposure apparatus 10 for manufacturing a semiconductor element.

  Alternatively, the light modulator 30 may be a transmissive liquid crystal microdisplay. In this case, the light modulator 30 illuminated in a planar shape by the illumination device 40 selects and transmits coherent light for each pixel, whereby a modulated image (light image) having a fine pattern is formed on the photosensitive medium 15. Can be formed.

  Moreover, it is preferable that the incident surface of the light modulator 30 has the same shape and size as the illuminated region LZ where the illumination device 40 emits coherent light. In this case, the coherent light from the illumination device 40 can be used with high efficiency for exposure of the photosensitive medium 15.

  The photosensitive medium 15 is, for example, a semiconductor wafer coated with a resist pattern. However, the type of the photosensitive medium 15 is not particularly limited, and a film coated with a photosensitive agent may be used.

  The photosensitive medium 15 is arranged as close as possible to the light modulator 30. Hereinafter, the reason will be described in detail. When the optical modulator 30 is, for example, a mask, when coherent light is incident on the edge of the mask, the coherent light is diffracted at the edge, and a diffraction image is obtained. The influence of the diffraction image increases as the distance between the light modulator 30 and the photosensitive medium 15 increases, and the original light image by the mask becomes blurred. Therefore, in this basic embodiment, the photosensitive medium 15 is arranged as close as possible to the optical modulator 30 in order to reduce the influence of the diffraction image.

  As described above, since the photosensitive medium 15 must be disposed as close as possible to the light modulator 30, the light modulator 30 is limited to a transmissive member, for example, a reticle or a liquid crystal micro display, and is a reflective type. The member is difficult to mount.

  Since the photosensitive medium 15 is arranged as close as possible to the light modulator 30, the light image modulated by the light modulator 30 can be guided to the surface of the photosensitive medium 15 as faithfully as possible.

  However, when the surface of the optical modulator 30 is a mirror surface, the coherent light from the hologram recording medium 55 is reflected by this mirror surface. When this reflected light is viewed by human eyes or captured by an imaging device, the hologram recording medium 55 itself is directly observed, so that speckle is visually recognized. The reason why speckles are visually recognized is that the mirror surface cannot diffuse a coherent light from the hologram recording medium 55 and generate a plurality of new speckle patterns. In other words, hologram recording in which each point always generates the same wavefront. This is because the wavefront from the medium 55 is reflected on the mirror surface and observed as it is.

  It is not very desirable that reflected light including speckles is irradiated from the light modulator 30. This is because depending on the laser intensity, there is a possibility of adverse effects on the human eye.

  Therefore, in order to avoid such reflected light, the light diffusing element 21 may be disposed between the hologram recording medium 55 and the optical modulator 30 as indicated by a broken line in FIG. The light diffusing element 21 is a relief or volume hologram recording medium 55 as a representative example, but the material is not particularly limited as long as the surface is a diffusing surface. For example, the glass may be processed to be opaque in a ground glass shape. Alternatively, the light diffusing element 21 may be opal glass, a relief diffusing plate, a microlens array, or the like.

  If such a light diffusing element 21 is provided, the coherent light diffused by the light diffusing element 21 is incident on the light modulator 30, and the surface of the light modulator 30 or the photosensitive medium 15 is a mirror surface. Speckle is less noticeable on these surfaces.

  An imaging optical system may be provided as an application example of FIG. FIG. 11 is a diagram showing a schematic configuration of one application example of FIG. In addition to the configuration of FIG. 10, the exposure apparatus 10 of FIG. 11 is disposed between the imaging optical system 25 disposed between the light modulator 30 and the photosensitive medium 15, and the irradiation apparatus 60 and the light modulator 30. The light diffusing element 21 is provided.

  The imaging optical system 25 forms an image on the photosensitive medium 15 with the coherent light modulated by the optical modulator 30. By providing the imaging optical system 25, enlargement exposure or reduction exposure is possible.

  In the exposure apparatus 10 of FIG. 10, the light diffusing element 21 is not necessarily essential, but in the exposure apparatus 10a of FIG. 11, the light diffusing element 21 is essential. Hereinafter, the reason will be described in detail.

  Since the coherent light continuously scans on the hologram recording medium 55, the incident angle of the coherent light from the irradiation device 60 to the illuminated area LZ also changes continuously and is incident on the photosensitive medium 15 from the diffractive optical element 50. The incident angle of coherent light also changes continuously. Therefore, when a human visually recognizes the surface of the photosensitive medium 15 from a distant position, the coherent light scattering pattern having no correlation is multiplexed and visually recognized by the human eye. Therefore, speckles generated corresponding to each scattering pattern are superposed and averaged and observed by the observer, and the speckles are not visually recognized.

  However, unlike the screen, the photosensitive medium 15 is for recording a light image from the light modulator 30. Recording an optical image on the photosensitive medium 15 is equivalent to recording an image that enters the human eye when the hologram recording medium 55 side is desired from the photosensitive medium 15. An imaging optical system 25 exists between the photosensitive medium 15 and the optical modulator 30, and each point on the imaged photosensitive medium 15 is recorded on the hologram via the imaging optical system 25 and the optical modulator 30. Corresponding to each point on the medium 55. As described above, each point on the hologram recording medium 55 always emits coherent light having a constant wavefront regardless of time. Therefore, when the hologram recording medium 55 side is desired from a certain point on the photosensitive medium 15, it is always Coherent light with a certain wavefront will be visible, and speckle will be conspicuous because there is no element that generates an uncorrelated speckle pattern. That is, an optical image including speckles is recorded on the photosensitive medium 15.

  On the other hand, when the light diffusing element 21 is disposed between the hologram recording medium 55 and the light modulator 30, coherent light having different incident angles with time is incident on each point of the light diffusing element 21, and scattering characteristics that vary with time. Light, that is, different wavefronts. As a result of the wavefront of the coherent light irradiated from each point of the light diffusing element 21 changing with time, when the light diffusing element 21 side is desired from each point on the photosensitive medium 15, the wavefront changes with time. The changing coherent light can be seen, and an uncorrelated speckle pattern is superimposed on the photosensitive medium 15, so that the speckle becomes inconspicuous.

  For the above reasons, the light diffusion element 21 is disposed between the hologram recording medium 55 and the light modulator 30 in this application mode. Ideally, the illuminated region LZ of coherent light diffused by the diffractive optical element 50 is preferably provided on the light diffusing element 21. In this way, the diffused light from each point of the diffractive optical element 50 naturally becomes incident light that changes with time on the light diffusing element 50, and speckles when the diffractive optical element 50 side is desired from the photosensitive medium 15. Disappears.

  Also in the exposure apparatus 10 according to the third embodiment, by providing the diffraction wavelength adjuster 3, the hologram recording medium can be used regardless of the individual difference, output energy, and temperature of the laser light source 61 and the temperature of the hologram recording medium 55. Since the 55 diffraction center wavelengths can coincide with the center wavelength of the coherent light from the laser light source 61, the illuminated area LZ can be illuminated uniformly, and the quality of the optical image recorded on the photosensitive medium 15 is improved.

(Specific form of irradiation device 60)
In the first and third embodiments described above, the example in which the irradiation device 60 includes the laser light source 61 and the scanning device 65 has been described. Although the scanning device 65 is an example of the uniaxial rotation type mirror device 66 that changes the traveling direction of the coherent light by reflection, the scanning device 65 is not limited thereto. As shown in FIG. 12, the scanning device 65 has a second rotation in which the mirror (reflection surface 66a) of the mirror device 66 intersects not only the first rotation axis RA1 but also the first rotation axis RA1. It may be rotatable about the axis RA2. In the example shown in FIG. 12, the second rotation axis RA2 of the mirror 66a is a first rotation axis RA1 extending in parallel with the Y axis of the XY coordinate system defined on the plate surface of the hologram recording medium 55. Are orthogonal. Since the mirror 66a is rotatable about both the first axis RA1 and the second axis RA2, the incident point IP of the coherent light from the irradiation device 60 to the diffractive optical element 50 is equal to that of the hologram recording medium 55. It can move in a two-dimensional direction on the plate surface. For this reason, as shown in FIG. 12 as an example, the incident point IP of the coherent light to the diffractive optical element 50 can be moved on the circumference.

  Further, the scanning device 65 may include two or more mirror devices 66. In this case, even if the mirror 66a of the mirror device 66 can be rotated only about a single axis, the incident point IP of the coherent light from the irradiation device 60 to the diffractive optical element 50 is represented by the hologram recording medium 55. Can be moved in a two-dimensional direction on the plate surface.

  Specific examples of the mirror device 66a included in the scanning device 65 include a MEMS mirror, a polygon mirror, and a galvano scanner.

  The scanning device 65 may include a reflection device that changes the traveling direction of coherent light by reflection, that is, a device other than the mirror device 66 described above as an example in the present embodiment. For example, the scanning device 65 may include a refractive prism, a lens, and the like.

  In the first place, the scanning device 65 is not essential, and the light source 61 of the irradiation device 60 is configured to be able to move, swing, rotate and the like with respect to the diffractive optical element 50. The coherent light emitted from the light source 61 may scan the hologram recording medium 55.

  Furthermore, although the light source 61 of the irradiation apparatus 60 has been described on the assumption that the laser light shaped as a linear light beam is oscillated, the present invention is not limited to this. In particular, in the embodiment described above, the coherent light irradiated to each position of the diffractive optical element 50 is shaped by the diffractive optical element 50 into a light beam that enters the illuminated region LZ. Therefore, there is no inconvenience even if the coherent light irradiated from the light source 61 of the irradiation device 60 to the diffractive optical element 50 is not accurately shaped. For this reason, the coherent light generated from the light source 61 may be diverging light. Further, the cross-sectional shape of the coherent light generated from the light source 61 may not be a circle but an ellipse or the like. Furthermore, the transverse mode of the coherent light generated from the light source 61 may be a multimode.

  When the light source 61 generates a divergent light beam, the coherent light is incident on a region having a certain area instead of a point when entering the hologram recording medium 55 of the diffractive optical element 50. In this case, the light diffracted by the hologram recording medium 55 and incident on each position of the illuminated area LZ is multiplexed in angle. In other words, at each moment, coherent light is incident on each position of the illuminated area LZ from a certain angle range. Speckle can be made more inconspicuous by such multiplexing of angles.

  Further, in FIG. 7 and the like, an example in which the coherent light reflected by the scanning device 65 is directly incident on the diffractive optical element 50 is shown, but a condensing lens is provided between the scanning device 65 and the diffractive optical element 50, You may make it make coherent light into a parallel light beam with this condensing lens, and enter into the diffractive optical element 50. In such an example, a parallel light beam is used as the reference light Lr instead of the above-described convergent light beam in the exposure process when the hologram recording medium 55 is manufactured. Such a hologram recording medium 55 can be produced and duplicated more easily.

(Specific form of diffractive optical element 50)
In the above-described embodiment, the example in which the diffractive optical element 50 is composed of the reflective volume hologram 55 using the photopolymer is shown, but the present invention is not limited thereto. Further, the diffractive optical element 50 may include a volume hologram that is recorded using a photosensitive medium including a silver salt material. Further, the diffractive optical element 50 may include a transmission type volume hologram recording medium 55 or a relief type (emboss type) hologram recording medium 55.

  However, in the relief (embossed) hologram, hologram interference fringes are recorded by the concavo-convex structure on the surface. However, in the case of this relief-type hologram, scattering due to the uneven structure on the surface may cause a loss of light amount and may cause a new unintended speckle generation. In this respect, the volume-type hologram is preferable. . In the volume hologram, since the hologram interference fringe is recorded as a refractive index modulation pattern (refractive index distribution) inside the medium, it is not affected by scattering due to the uneven structure on the surface.

  However, even volume holograms that are recorded using a photosensitive medium containing silver salt material may cause light loss due to scattering by silver salt particles, and may cause unintended new speckle generation. There is sex. In this respect, the hologram recording medium 55 is preferably a volume hologram using a photopolymer.

  Further, in the recording process shown in FIG. 5, a so-called Fresnel type hologram recording medium 55 is produced. A Fourier transform type hologram recording medium 55 obtained by performing recording using a lens is produced. It doesn't matter. However, when the Fourier transform type hologram recording medium 55 is used, a lens may also be used during image reproduction.

  Further, the striped pattern to be formed on the hologram recording medium 55, for example, the refractive index modulation pattern or the uneven pattern, does not use the actual object light Lo and the reference light Lr, but the planned wavelength and incident direction of the reproduction illumination light La. In addition, it may be designed using a computer based on the shape and position of the image to be reproduced. The hologram recording medium 55 obtained in this way is also called a computer-generated hologram. When a plurality of coherent lights having different wavelength ranges are irradiated from the irradiation device 60 as in the above-described modification, the hologram recording medium 55 as a computer-generated hologram corresponds to each coherent light in each wavelength range. The coherent light in each wavelength region may be diffracted in the corresponding region to reproduce an image.

(Lighting method)
In the above-described form, the irradiation device 60 is configured to be able to scan the coherent light on the diffractive optical element 50 in a one-dimensional direction, and the holographic recording medium 55 of the diffractive optical element 50 is irradiated to each position. An example in which light is diffused in a two-dimensional direction and the illumination device 40 illuminates a two-dimensional illuminated area LZ by this is shown. However, as already described, the present invention is not limited to such an example. For example, the irradiation device 60 is configured to be able to scan the coherent light in the two-dimensional direction on the diffractive optical element 50, and The hologram recording medium 55 of the diffractive optical element 50 is configured to diffuse the coherent light irradiated to each position in a two-dimensional direction. As a result, as shown in FIG. The illuminated area LZ may be illuminated.

  Further, as already mentioned, the irradiation device 60 is configured to be able to scan the coherent light on the diffractive optical element 50 in a one-dimensional direction, and the hologram recording medium 55 of the diffractive optical element 50 is provided at each position. The coherent light applied to the light source may be diffused in a one-dimensional direction, so that the illumination device 40 may illuminate the one-dimensional illuminated area LZ. In this aspect, the scanning direction of the coherent light by the irradiation device 60 and the diffusion direction of the hologram recording medium 55 of the diffractive optical element 50 may be parallel.

  Further, the irradiation device 60 is configured to be able to scan the coherent light in the one-dimensional direction or the two-dimensional direction on the diffractive optical element 50, and the hologram recording medium 55 of the diffractive optical element 50 is irradiated to each position. The coherent light may be configured to diffuse in a one-dimensional direction. In this embodiment, the diffractive optical element 50 has a plurality of hologram recording media 55, and the illumination device 40 sequentially illuminates the illuminated regions LZ corresponding to the hologram recording media 55, so that the illumination device 40 forms a two-dimensional region. You may make it illuminate. At this time, each illuminated area LZ may be sequentially illuminated at a speed as if it were illuminated simultaneously by the human eye, or it can be recognized that the illuminated area LZ is also illuminated sequentially by the human eye. It may be illuminated sequentially at such a slow speed.

  The aspect of the present invention is not limited to the individual embodiments described above, and includes various modifications that can be conceived by those skilled in the art, and the effects of the present invention are not limited to the contents described above. That is, various additions, modifications, and partial deletions can be made without departing from the concept and spirit of the present invention derived from the contents defined in the claims and equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 1st temperature measurement part, 2nd temperature measurement part, 3 diffraction wavelength regulator, 10 exposure apparatus, 11 1st table storage part, 12 2nd table storage part, 13 temperature adjustment part, 15 photosensitive medium, 20 projection apparatus , 21 Light diffusing element, 30 light modulator, 40 illumination device, 50 optical element, 55 hologram recording medium, 58 hologram photosensitive material, 60 irradiation device, 61 laser light source, 65 scanning device, 66 mirror device (reflection device), 66a Mirror (reflection surface), 70 imaging optical system, 80 projection optical system, 81 projection lens, LZ illuminated area

Claims (11)

A diffractive optical element to illuminate overlapping the illuminated area at incident on each point of the incident surface coherent light,
An irradiation device for irradiating coherent light toward the incident surface of the diffractive optical element;
A first temperature measurement unit for measuring the temperature of the irradiation device;
A second temperature measurement unit for measuring the temperature of the diffractive optical element;
A diffractive wavelength adjuster that adjusts the diffraction center wavelength of the diffractive optical element according to a shift in the center wavelength of coherent light emitted by the irradiation device, based on the temperature measurement results of the first and second temperature measurement units;
A light source wavelength adjuster that adjusts a center wavelength of coherent light emitted by the irradiation device based on a temperature measurement result of the first temperature measurement unit;
The diffraction wavelength regulator such that said diffraction center wavelength of the diffractive optical element is coincident with the coherent light center wavelength of the adjusted at the light source wavelength adjustment unit, the diffractive optical element by varying the temperature of the diffractive optical element And a temperature adjusting unit for adjusting the diffraction center wavelength of the illumination device. The diffraction wavelength adjuster is
A first table storage unit for storing a first table indicating a correspondence relationship between the temperature of the irradiation device and the shift amount of the central wavelength of the coherent light irradiated by the irradiation device;
A second table storage unit for storing a second table indicating a correspondence relationship between the temperature of the diffractive optical element and the shift amount of the diffraction center wavelength of the diffractive optical element;
The temperature adjusting unit varies the temperature of the diffractive optical element based on the temperature measurement results of the first and second temperature measuring units and the first and second tables, and the diffraction center of the diffractive optical element The illumination device according to claim 1, wherein the wavelength is adjusted. The first table storage unit shows the correspondence relationship between the output energy of the coherent light irradiated by the irradiation device, the temperature of the irradiation device, and the shift amount of the central wavelength of the coherent light irradiated by the irradiation device. The lighting device according to claim 2 , wherein one table is stored. 4. The illumination device according to claim 2 , wherein the temperature adjustment unit is in direct contact with the diffractive optical element to heat or cool the diffractive optical element. 5. 4. The illumination device according to claim 2 , wherein the temperature adjusting unit is disposed physically apart from the diffractive optical element, and heats or cools the diffractive optical element with warm air or cold air. . The irradiation device includes:
A light source that emits coherent light;
By changing the traveling direction of the coherent light emitted from the light source, any one of claims 1 to 5, characterized in that it has a scanning device for scanning the coherent light on the surface of the diffractive optical element The lighting device described in 1. The lighting device according to any one of claims 1 to 6 ,
And a light modulator disposed at a position overlapping the illuminated area and illuminated by the illumination device. The projection apparatus according to claim 7 , further comprising a projection optical system that projects a modulated image obtained on the light modulator onto a screen. The lighting device according to any one of claims 1 to 6 ,
A light modulator disposed at a position overlapping the illuminated area and illuminated by the illumination device,
An exposure apparatus, wherein the coherent light modulated by the light modulator is guided to a surface of a photosensitive medium. The exposure apparatus according to claim 9 , wherein the light modulator is disposed in proximity to the photosensitive medium. The exposure apparatus according to claim 9 , further comprising an imaging optical system that forms an image of the coherent light modulated by the optical modulator on a surface of the photosensitive medium.

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