JP4533169B2 - Interference exposure equipment - Google Patents

Description

  The present invention relates to an interference exposure apparatus having an optical monitor control unit for producing a diffraction grating (hologram), and further, light for duplicating the diffraction grating (hologram) using an original diffraction grating (master hologram). The present invention relates to an interference exposure apparatus including a monitor control unit.

  Conventionally, there is a two-beam interference exposure method as one method for producing a diffraction grating (hologram). In this two-beam interference exposure method, a light beam from the same light source (for example, a laser light source) is separated into two light beams, and these two light beams are interfered to generate interference fringes. This is a method for obtaining a diffraction grating (hologram) by developing after exposing and recording (see, for example, Patent Document 1).

As an example of a configuration used when producing a diffraction grating (hologram) using the two-beam interference exposure method, there is a configuration including an exposure optical system as shown in FIG. 10 (for example, Patent Document 2).
In the configuration shown in FIG. 10, the exposure laser light source 101, the spatial filters 102 and 103, the collimating lens 104, the half mirror 105, the mirrors 106a and 106b, the recording material 107, the monitor light source 108, and the light reception. Instrument 109. The spatial filter includes an objective lens 102 and an aperture 103, and is used to cut noise (higher order transverse mode) of laser emitted light.

In the configuration shown in FIG. 10, the laser light from the light source is converted into a parallel light beam by the collimator lens 104 and separated into two light beams by the half mirror 105. When these two light beams are superimposed again using the mirrors 106a and 106b, interference fringes determined by the laser wavelength and the angle formed by the two light beams are generated. When the recording material 107 is disposed on the interference fringes, it is possible to record irregularities and phase differences on the recording material by the intensity of the interference fringes.
As the recording material, a photosensitive material such as a photoresist or a photopolymer is used. In the configuration shown in FIG. 10, the recording (exposure) wavelength is 514.5 nm, and the monitor light is 632.8 nm.

Incidentally, there is also a demand for monitoring how much the diffraction grating is produced during the two-beam interference exposure. At this time, if monitoring is performed at the same wavelength as the exposure wavelength, the recording material is exposed by the monitor light, and a desired diffraction grating cannot be manufactured. In addition, when monitoring at a wavelength at which the absorption of the recording material is not negligible even if it is different from the exposure wavelength, only a diffraction grating with low efficiency may be produced due to exposure with monitor light.
As a method of performing exposure while monitoring, a method of using a monitor light having the same wavelength as the reproduction wavelength and using a recording material which can be recorded (absorbed) at the exposure wavelength but not recorded at the reproduction wavelength (absorbed) can be considered.
For example, in FIG. 10, the exposure laser 101 is a blue laser (argon laser), and the monitor light source 108 is a red helium neon laser. Then, by selecting a material that can be recorded with blue light on the recording material 107 and cannot be recorded with red having a longer wavelength than blue, the production of the diffraction grating can be prevented from being adversely affected by the monitor light.

In addition, when a diffraction grating (hologram) that diffracts only specific polarized light is produced using the two-beam interference exposure method, for example, a monitor described in Non-Patent Document 1 can be used as a configuration that is not affected by monitor light. There is a configuration including an attached exposure optical system.
The holographic PDLC element described in Non-Patent Document 1 is an element having a diffraction grating (hologram) that diffracts only P-polarized light. The light source for monitoring in manufacturing this element has an oscillation wavelength different from that of the light source for exposure, and the recording material is not sensitive at the wavelength of the monitor light source, so the recording material is not exposed with the monitor light source. Therefore, if there is no problem even if the exposure wavelength and the monitor wavelength are different, the exposure optical system with a monitor is very effective.

JP-A-10-39125 JP 2002-60429 A Fig. 1 of “Property of Polarization Dependent Holographic Polymer Dispersed Liquid Crystal Device and its Application for Information Display”, Ogiwara et al. IDW’02 Digest P.161

In the interference exposure apparatus configured as shown in FIG. 10, if the exposure wavelength and the monitor wavelength are in the same wavelength band, the recording material is exposed by the monitor light, so the monitor light is changed to a short pulse light or attenuated to a low power density. After that, it was necessary to irradiate the recording material. For this reason, the sensitivity (monitor level) of the monitor is lowered, and it is difficult to end the exposure with an appropriate exposure amount.
Therefore, the present inventors have devised that, of the diffracted light from the diffraction grating by the exposure beam, slightly generated diffracted light of orders other than 0th order and + 1st order is used as monitor light.
However, an element that diffracts with P-polarized light but does not diffract S-polarized light as in the hologram described in Non-Patent Document 1 cannot monitor diffracted light because it uses S-polarized light for the exposure beam of the interference exposure system.

The present invention has been made in view of the above circumstances, and even when a diffraction grating (hologram) that diffracts only with one polarized light (P-polarized light or S-polarized light) is produced by two-beam interference exposure, monitor exposure can be performed. It is an object of the present invention to provide an interference exposure apparatus having a configuration that can be used.
Further, the present invention provides an interference exposure having a configuration capable of reducing the solid exposure of the recording material by the monitor light when the diffraction grating (hologram) diffracted only by one polarized light (P-polarized light or S-polarized light) is monitored. An object is to provide an apparatus.
Furthermore, the present invention can perform monitor exposure even when only one light source is used and a diffraction grating (hologram) that diffracts only with one polarized light (P-polarized light or S-polarized light) is produced by two-beam interference exposure. An object of the present invention is to provide an interference exposure apparatus having a configuration.
Furthermore, the present invention reduces the solid exposure of the recording material by the monitor light when only one light source is used to monitor exposure of a diffraction grating (hologram) that diffracts only with one polarized light (P-polarized light or S-polarized light). It is an object of the present invention to provide an interference exposure apparatus having a configuration that can be made to operate.
Furthermore, in the present invention, monitor exposure can be performed even when a diffraction grating (hologram) that diffracts only with one polarized light (P-polarized light or S-polarized light) is duplicated using an original diffraction grating (master hologram). It is an object of the present invention to provide an interference exposure apparatus having a configuration that can be used.
Furthermore, the present invention is also applicable to a case where only one light source is used and a diffraction grating (hologram) that diffracts only with one polarized light (P-polarized light or S-polarized light) is reproduced using an original diffraction grating (master hologram). An object of the present invention is to provide an interference exposure apparatus having a configuration capable of performing monitor exposure.

To achieve the above object, the present invention that has adopted the technical means described below.

The first means of the present invention splits the emitted light from a coherent light source into a plurality of light beams, and divides the plurality of light beams into a predetermined direction and a predetermined direction with respect to a recording material diffracted only by one polarized light . In the interference exposure apparatus for producing a desired diffraction grating by generating interference fringes by irradiating at an incident angle and exposing the recording material with the interference fringes, the number of the plurality of light beams is M (M ≧ 3 ). (M-1) light beams are combined at a predetermined orientation and a predetermined incident angle to expose the recording material, and the remaining one light beam rotates the plane of polarization by 90 degrees, A light monitor control unit is provided that monitors the diffracted light intensity by irradiating the recording material and blocks light from the light source when a predetermined light intensity is obtained or exceeds a predetermined light intensity. (Claim 1 ).
According to a second means of the present invention, in the interference exposure apparatus of the first means, the light emitted from the light source is split into a plurality of light beams by a diffraction grating, and the polarization plane of the zero-order light is rotated by 90 degrees. (Claim 2).
According to a third means of the present invention, in the interference exposure apparatus of the first or second means, the recording material is irradiated with the light of the remaining one light beam by a short pulse light, or the (M− 1) Irradiation is performed with a power density smaller than the power density of one light beam (Claim 3 ).

According to a fourth means of the present invention, light from a light source having coherence is incident on the first diffraction grating, and interference fringes generated by transmission diffraction first-order light and zero-order light from the first diffraction grating. In the interference exposure apparatus for producing a desired diffraction grating by exposing a recording material that is diffracted only with one polarized light, the light beam from the light source is split into two light beams, and one light beam is the first diffraction grating. The other light beam is rotated 90 degrees on the polarization vibration surface, and then irradiated to the recording material to monitor the diffracted light intensity. When a predetermined light intensity is obtained, or exceeds the predetermined light intensity. it is characterized in that it comprises an optical monitoring control unit for blocking the light from the light source when the (claim 4).

According to a fifth means of the present invention, in the interference exposure apparatus of any one of the first to fourth means, a holographic polymer dispersed liquid crystal is used as a recording material that diffracts only with the one polarized light. (Claim 5).
According to a sixth means of the present invention, in the interference exposure apparatus according to any one of the first to fifth means, the diffraction grating region including the dummy region of the recording material is exposed, and the monitoring light flux is Only the dummy region is irradiated (Claim 6 ).

In the interference exposure apparatus of the first and second means, the emitted light from the light source having coherence is branched into M (natural number of M ≧ 3 ) light beams, and (M−1) light beams are respectively predetermined. The recording material is exposed at a predetermined incident angle and the recording material is exposed, and the remaining one light beam rotates the plane of polarization by 90 degrees, and irradiates the recording material to monitor the diffracted light intensity. When light intensity is obtained, or by providing a light monitor control unit that blocks light from the light source when a predetermined light intensity is exceeded, for example, when exposing a diffraction grating that is diffracted only by P-polarized light, Even when S-polarized light is used for the exposure beam of the interference exposure system, monitor exposure can be performed because P-polarized light is used for the monitor light, and interference fringes are generated by the monitor light and the exposure beam. Without adversely affecting the diffraction grating, Furthermore, an exposure apparatus with a monitor can be realized with only one light source.

In the interference exposure apparatus of the third means, in addition to the configuration of the first or second means, the recording material is irradiated with the light of the remaining one light beam with short pulse light, or (M-1) By irradiating with a power density smaller than the power density of each light beam, for example, when exposing a diffraction grating that is diffracted only by P-polarized light, even when S-polarized light is used as the exposure beam of the interference exposure system, monitor light Since P-polarized light is used for the monitor, monitor exposure can be performed, interference fringes between the monitor light and the exposure beam are not generated, and furthermore, monitoring is performed with short pulse light or low power density light. Further, the solid exposure of the recording material by the monitor light can be suppressed to a minimum, and furthermore, the exposure apparatus with a monitor can be realized with only one light source.

In the interference exposure apparatus of the fourth means, light from a coherent light source is incident on the first diffraction grating, and interference is generated by transmission diffraction first-order light and zero-order light from the first diffraction grating. When a desired diffraction grating is produced by exposing a recording material that is diffracted by only one polarized light with a fringe, the light beam from the light source is split into two light beams, and one light beam is directed to the first diffraction grating. The other light beam is rotated 90 degrees on the polarization vibration surface, and then irradiated to the recording material to monitor the diffracted light intensity. When a predetermined light intensity is obtained, or exceeds the predetermined light intensity. By providing an optical monitor control unit that sometimes blocks light from the light source, for example, when using a s-polarized light as an exposure beam in an interference exposure system when performing duplication exposure of a diffraction grating that diffracts only with p-polarized light, Because P-polarized light is used for the monitor light, Nitter exposure is possible, interference fringes due to monitor light and exposure beam are not generated, adverse effects on the diffraction grating can be reduced, and duplication with monitor is possible with only one light source. An exposure apparatus can be realized.

In the interference exposure apparatus of the sixth means, in addition to the configuration of any one of the first to fifth means, a diffraction area is provided in the diffraction grating to be manufactured, and the dummy area is irradiated with monitor light. The area used as can be prevented from being affected by the solid exposure by the monitor light, and an exposure apparatus with a monitor can be constructed in which the adverse effects of the monitor light are prevented.

  Hereinafter, the configuration, operation and action of the present invention will be described in detail based on the embodiments shown in the drawings.

[Example 1]
FIG. 1 is a schematic block diagram of an interference exposure apparatus for explaining a first embodiment of the present invention. In FIG. 1, the outgoing beam from the first laser light source 11 a is converted into a 0th order beam transverse mode by the spatial filter 12, and the divergent light from the spatial filter 12 is converted into a parallel beam by the collimator lens 13. This parallel light beam is divided into two by the half mirror 14, and each beam is irradiated onto the recording material 16 at a predetermined incident angle using the mirrors 15a and 15b.
The spatial filter 12 includes an objective lens and a pinhole (not shown). Moreover, the recording material 16 can utilize what is mentioned later.

  As the monitor light, the recording material 16 is irradiated with a beam emitted from the second laser light source 11b having substantially the same oscillation wavelength as that of the first laser light source 11a for exposure. However, the polarization vibration plane of the first laser light source 11a is in a direction perpendicular to the paper surface of FIG. 1 (that is, S-polarized light on the recording material surface), whereas the polarization vibration of the second laser light source 11b for monitoring is used. The surface is set parallel to the paper surface (that is, P-polarized light on the recording material surface).

  As the recording material 16, a holographic PDLC (polymer dispersion type liquid crystal) as described in Non-Patent Document 1 described above can be used. FIG. 2 shows an example of a sectional structure of the holographic PDLC. In the holographic PDLC 20, as shown in FIG. 2, a polymer layer 22 and a liquid crystal layer 23 are periodically formed, and the refractive index of the polymer layer 22 and the ordinary light refractive index of the liquid crystal layer 23 are substantially equal. The liquid crystal is aligned so as to be perpendicular to the wall of the polymer layer 22. Therefore, the S-polarized light does not feel a difference in refractive index between the polymer layer 22 and the liquid crystal layer 23 and does not diffract. However, since the P-polarized light 24 feels a difference between the extraordinary refractive indexes of the polymer layer 22 and the liquid crystal layer 23, the P-polarized light 24 is diffracted by expressing the function of the diffraction grating. Such a holographic PDLC 20 is manufactured by sandwiching a liquid mixture of a photopolymerizable monomer and a photononpolymerizable liquid crystal between two glass substrates 21 and performing interference exposure.

  In the interference exposure apparatus having the configuration shown in FIG. 1, monitor light is irradiated from the second laser light source 11b during interference exposure of the recording material 16, the diffracted light is received by the light receiving element 17, and the light intensity is a predetermined value. Or when the predetermined value is exceeded, the first laser light source 11a is passed through an optical monitor control unit (for example, a control circuit comprising a microcomputer, a memory, an input / output circuit, an electromagnetic shutter drive circuit, etc.) 18. A signal for blocking the laser beam is sent to the electromagnetic shutter 19 to block the exposure laser beam.

  By the way, if the Bragg diffraction grating is produced by the two light beams shown in FIG. 1, the monitoring beam cannot be incident light satisfying the Bragg condition. That is, from the first laser light source 11a side of the recording material 16, the emitted light of the second laser light source 11b cannot be matched with either of the two light beams, and diffracted light is also emitted from the opposite surface. The light-receiving element 17 cannot be disposed because the traveling direction differs from that of one of the light beams of the first laser light source 11a by 180 ° and the beams overlap. For this reason, the monitor light needs to have an incident angle deviated from the Bragg angle. However, the relationship between the deviation from the Bragg angle and the diffraction efficiency can be predicted from Kogelnik's theory. As an example, as a parameter in which diffraction efficiency is formed, the refractive index modulation (amplitude) of the diffraction grating is taken on the horizontal axis and the diffraction efficiency is taken on the vertical axis, as shown in FIG. In the holographic PDLC 20 as shown in FIG. 2, the refractive index modulation (amplitude) corresponds to a half value of the refractive index difference between the polymer layer 22 and the liquid crystal layer 23. Immediately after the start of exposure, the monomer and liquid crystal are mixed, so the refractive index modulation (amplitude) is 0, and the value increases as the exposure is performed. In FIG. 3, the efficiency of the incident angle that satisfies the Bragg condition is plotted with a curve 31, and the efficiency of a light beam (assumed to be monitor light) deviated 20 ° from the Bragg incident angle is plotted with a curve 32. As the diffraction grating is completed, the intensity of the monitor light is indicated by a curve indicated by reference numeral 32. For example, if exposure is interrupted at an amount of received light at which the diffraction efficiency of monitor light is 1%, a diffraction grating having a diffraction efficiency of 90% can be produced. Of course, considering the time lag of the control system, the desired diffraction grating characteristics can be obtained if exposure is stopped earlier by that much.

  In this embodiment, a two-beam interference exposure system is used. However, the present invention can be used if the exposure beam has two or more beams. In addition, although interference fringes are generated with parallel light beams (collimated light), the effects of the present invention are not affected by the spherical wave of convergent light or divergent light.

[Example 2]
FIG. 4 is a schematic block diagram of an interference exposure apparatus for explaining a second embodiment of the present invention. 4, the same components as those in FIG. 1 are denoted by the same reference numerals.
In the present embodiment, a light intensity modulator 41 is disposed between the second laser light source 11 b and the recording material 16. The polarization of the monitor light to the recording material 16 is parallel to the paper surface (P-polarized light).
The light intensity modulator 41 uses, for example, twisted nematic liquid crystal, and has a configuration in which a polarizing plate is arranged on the output side of the twisted nematic liquid crystal. The light intensity of the incident light can be controlled. In addition, when an electric field is applied in a pulse shape, an optical pulse with a pulse width up to the order of milliseconds can be generated.

When the monitor light from the second laser light source 11b is about the same as the exposure wavelength, there may be a problem of the solid exposure of the portion of the recording material 16 irradiated with the monitor light. Then, the light intensity modulator 41 can reduce the power density of the monitor light or irradiate it as a light pulse, so that the solid exposure can be minimized.
Note that a light intensity modulator using an electro-optic crystal can be used to make the monitor light from the second laser light source 11b an optical pulse shorter than milliseconds. If the second laser light source 11b itself is a pulsed laser device, the light intensity modulator 41 can be omitted.

[Example 3]
FIG. 5 is a schematic block diagram of an interference exposure apparatus for explaining a third embodiment of the present invention. This interference exposure apparatus includes a laser light source 51, an electromagnetic shutter 19, a spatial filter 12, a collimating lens 13, an optical branching element 52, mirrors 53a and 53b, a λ / 2 plate 54, a recording material 55, a light receiving element 56, and an optical monitor control. The unit 18 is configured.
The optical branching element 52 is used to split the laser beam into three, and for example, a diffraction grating can be used. The light branching element 52 separates the + 1st order diffracted light and the −1st order diffracted light at a predetermined diffraction angle, and the 0th order light is incident on the λ / 2 plate 54. The laser light is originally linearly polarized light (S-polarized light) perpendicular to the paper surface. However, if the slow axis of the λ / 2 plate 54 is inclined by 45 ° from the vibration surface of the laser light, the laser light is emitted from the λ / 2 plate 54. The incident light becomes linearly polarized light (P-polarized light) parallel to the paper surface.

  The three lights demultiplexed by the light branching element 52 are superimposed on the recording material 55 by the mirrors 53a and 53b. However, the polarized light (P-polarized light) parallel to the paper does not interfere with the remaining two lights (S-polarized light). Therefore, the recording material 55 has an intensity distribution in which the interference fringes of the two beams deflected by the mirrors 53a and 53b and the third beam intensity are added as a DC component.

  If the recording material 55 of the type that diffracts with P-polarized light as described in Example 1 is used, the diffracted light can be produced by monitoring the diffracted light of the beam (monitor light) that is oscillated parallel to the paper surface. I can know. As described in the first embodiment, the control procedure for stopping the exposure when the monitor light is received by the light receiving element 56 and the light intensity reaches a predetermined value or exceeds the predetermined value. Therefore, the description is omitted here.

  According to the configuration of the present embodiment, monitor light can be generated with only one light source 51 for exposure, and unnecessary interference fringes are not generated by the monitor light and the exposure beam. The exposure apparatus with a monitor can be realized with only one light source.

  In the present embodiment, the interference exposure system is constructed by splitting into three beams and using two light beams. However, the effect of the present invention is also affected by a configuration in which an exposure beam having three or more light beams is used by branching to four or more light beams. Not. In addition, although interference fringes are generated with parallel light beams (collimated light), the effects of the present invention are not affected by the spherical wave of convergent light or divergent light. In addition, a λ / 2 plate 54 is used, but in addition to that, a phase difference plate other than λ / 2 is used to make elliptically polarized light, and only polarized light parallel to the paper surface is a polarizing plate or a Glan-Thompson prism. It is good also as a structure taken out using polarizing prisms, such as.

[Example 4]
FIG. 6 is a schematic block diagram of an interference exposure apparatus for explaining a fourth embodiment of the present invention. In the present embodiment, the λ / 2 plate 54 of the third embodiment is replaced with a light intensity modulator 60. FIG. 7 is a diagram for explaining a configuration example of the light intensity modulator 60. In the light intensity modulator 60 shown in FIG. 7, a nematic liquid crystal 72 is sandwiched between two light-transmitting substrates 71. On the liquid crystal layer side of the translucent substrate 71, an ITO (transparent electrode) and an alignment film (not shown) are formed, and a twisted nematic liquid crystal mode is set by alignment processing. A polarizing plate 72 is disposed on the exit side of the twisted nematic liquid crystal, and the transmission axis is aligned in a direction parallel to the paper surface. In this light intensity modulator 60, the light intensity of the emitted light can be controlled by the amount of voltage applied to the transparent electrode, and it is possible to generate a light pulse of about milliseconds if the applied voltage is made pulsed. It is.

  If such a light intensity modulator 60 is used, the control of the power density of the P-polarized beam in FIG. 6 is simplified. By reducing the power density of this monitor light or by making it into an optical pulse, the amount of exposure added in a DC manner during exposure can be reduced, and the reduction in contrast of the refractive index modulation of the liquid crystal can be suppressed. it can. In other words, the solid exposure component by the monitor light can be reduced, which can contribute to the production of a diffraction grating with high diffraction efficiency.

[Example 5]
FIG. 8 is a schematic block diagram of the principal part of an interference exposure apparatus for explaining a fifth embodiment of the present invention. In FIG. 8, only the first diffraction grating (original diffraction grating) 81, the recording material 82, and the vicinity thereof are illustrated, and the first laser light source for exposure and the second laser light source for monitoring are illustrated. Is omitted.
In FIG. 8, a first laser beam 83 emitted from a first laser light source (not shown) is incident on the first diffraction grating 81. The first diffraction grating 81 generates transmitted light (zero-order light) 84 and diffracted first-order light 85 at a ratio of approximately 1: 1, and interference fringes are formed at a portion (diffraction grating region) 88 where these two light beams intersect. . The recording material 82 is placed in the interference fringe region to expose the interference fringe, and the first diffraction grating 81 is replicated on the recording material 82. Although not shown, if necessary, a spatial filter, a condenser lens, or the like is disposed in the optical path between the first laser light source and the first diffraction grating 81, and the laser light 83 is changed to a desired wavefront. 1 is incident on one diffraction grating 81.

  A laser beam 86 from a second laser light source (not shown) having an oscillation wavelength equivalent to that of a first laser light source (not shown) is set to P-polarized light (vibration plane parallel to the paper surface), and is irradiated to the recording material 82 as monitor light. . Since this laser beam 86 is equivalent to the exposure wavelength, it is completely exposed even in the beam plane. Therefore, the monitor light 86 is set to be equal to or more than the diffraction grating region 88. This is because if the monitor light is smaller than the diffraction grating region 88, only the diffraction grating in the portion irradiated with the monitor light changes the diffraction efficiency.

In this embodiment, since the monitor light 86 is incident from the side opposite to the first diffraction grating 81, the diffracted light 87 from the recording material 82 is incident on the first diffraction grating 81, and a part thereof. Diffracted. The diffracted light 87 is detected by a light receiving element (not shown).
The ratio of this diffraction depends on the P-polarized diffraction efficiency of the first diffraction grating. For this reason, it is necessary to consider the transmittance of the first diffraction grating 81 with respect to the incident light of the diffracted light 87. For example, in order to interrupt the exposure with the diffraction efficiency B [%] of the monitor light, the diffraction efficiency of the P-polarized light of the first diffraction grating 81 is A [%], and the light intensity of the monitor light 86 is P0 [mW]. The received light intensity P1 of the monitor light by the light receiving element is
P1 = P0 × B / 100 × A / 100
The electromagnetic shutter (not shown) may be closed at the moment when this value is reached or at the moment when this value is exceeded.
In FIG. 8, the monitor light 86 is incident from the side opposite to the first diffraction grating 81, but the monitor light may be irradiated from the first diffraction grating side.

  According to the configuration of the present embodiment, the recording material 82 is duplicated and exposed using the original diffraction grating (first diffraction grating) 81, and particularly when the diffraction grating having a diffraction effect with P-polarized light is duplicated and exposed. The production status of the diffraction grating can be monitored at a wavelength equivalent to the exposure wavelength.

[Example 6]
As a modification of the fifth embodiment, the exposure laser beam is split into two using an optical branching element, one is used for the exposure beam 83 in FIG. 8, and the other is polarized through a mirror, a λ / 2 plate, or the like. The surface may be rotated 90 ° and used as the monitor light 86. In this case, the exposure laser beam 83 and the monitor light 86 are beams from the same laser light source, but since the polarization planes are orthogonal, the transmitted light (zero-order light) 84, the monitor light 86, and the first diffraction order. Interference fringes are not generated in the light 85 and the monitor light 86, respectively. Therefore, it is possible to perform monitor exposure using only one laser light source without generating unnecessary interference fringes at the time of replica exposure of a diffraction grating having high polarization efficiency with P polarization.

[Example 7]
FIG. 9 is a schematic block diagram of the principal part of an interference exposure apparatus for explaining a seventh embodiment of the present invention. In FIG. 9, only the vicinity of the recording material 91 is illustrated, and illustration of the first laser light source for exposure, the second laser light source for monitoring, and the like is omitted.
In FIG. 9, exposure beams 94 a and 94 b from a laser light source (not shown) that exposes the recording material 91 are exposed including the dummy region 93 in addition to the grating region 92 when the diffraction grating is used. The monitor light 95 is P-polarized with respect to the recording material 91, irradiates the dummy region 93, and the diffracted light is received by the light receiving element 96.

  The present embodiment can be applied to the first to sixth embodiments already described, and the monitor light 95 uses a second laser light source for monitoring equivalent to the exposure wavelength as shown in FIGS. Also, as shown in FIGS. 5 and 6, the light emitted from the laser light source for exposure may be branched and used. The exposure beams 94a and 94b only need to have two or more light beams, and the number of light beams does not affect the effect of the present invention. Further, exposure using an original diffraction grating may be used.

  According to the present embodiment, the solid exposure of the recording material 91 with the monitor light 95 adversely affects the characteristics of the diffraction grating to be produced (for example, when the diffraction efficiency is reduced due to the monitor light irradiation). Demonstrate. That is, since the dummy region 93 of the recording material 91 is not used after the diffraction grating is manufactured, there is an advantage that the monitor light does not need to have a low power density or a light pulse.

As described above, according to the present invention, even when a diffraction grating (hologram) that diffracts only with one polarized light (P-polarized light or S-polarized light) is produced by two-beam interference exposure, the adverse effect of monitor light is reduced. Thus, an interference exposure apparatus having a configuration capable of performing monitor exposure can be realized. Further, in the present invention, when monitor exposure is performed on a diffraction grating (hologram) that is diffracted only by one polarized light (P-polarized light or S-polarized light), solid exposure of the recording material by the monitor light can be reduced.
Furthermore, in the present invention, even when only one light source is used and a diffraction grating (hologram) that diffracts only with one polarized light (P-polarized light or S-polarized light) is produced by two-beam interference exposure, the adverse effect of the monitor light is reduced. Thus, an interference exposure apparatus having a configuration capable of performing monitor exposure can be realized. Further, in the present invention, when only one light source is used and a diffraction grating (hologram) that is diffracted only by one polarized light (P-polarized light or S-polarized light) is subjected to monitor exposure, solid exposure of the recording material by the monitor light is reduced. be able to.
Furthermore, in the present invention, even when a diffraction grating (hologram) that diffracts only with one polarized light (P-polarized light or S-polarized light) is duplicated using an original diffraction grating (master hologram), adverse effects due to monitor light are reduced. Thus, an interference exposure apparatus having a configuration capable of performing monitor exposure can be realized.
Further, in the present invention, when only one light source is used and a diffraction grating (hologram) that diffracts only with one polarized light (P-polarized light or S-polarized light) is reproduced using an original diffraction grating (master hologram), It is possible to realize an interference exposure apparatus configured to perform monitor exposure while reducing adverse effects due to monitor light.
Therefore, by using the interference exposure apparatus of the present invention, the adverse effect can be reduced even when performing monitor exposure, and a diffraction grating (hologram) with high diffraction efficiency can be produced or duplicated.
The diffraction grating (hologram) produced or duplicated by the interference exposure apparatus of the present invention has high diffraction efficiency, and an optical head for various optical disks such as a compact disk (CD), a digital versatile disk (DVD), and a high-density DVD. (Optical pickup) and optical heads (optical pickups) for magneto-optical disks, etc. In addition to this, it can be used in various fields such as illumination optical systems and spectroscopes of image display devices. .

It is a schematic block diagram of the interference exposure apparatus for demonstrating the 1st Example of this invention. It is principal part sectional drawing of holographic PDLC which shows an example of a recording material. It is a figure which shows the efficiency of the Bragg angle with respect to the refractive index modulation (amplitude) of a diffraction grating, and the diffraction efficiency of monitor light. It is a schematic block diagram of the interference exposure apparatus for demonstrating the 2nd Example of this invention. It is a schematic block diagram of the interference exposure apparatus for demonstrating the 3rd Example of this invention. It is a schematic block diagram of the interference exposure apparatus for demonstrating the 4th Example of this invention. It is a figure for demonstrating the structural example of the light intensity modulator used with the interference exposure apparatus of FIG. It is a schematic principal part block diagram of the interference exposure apparatus for demonstrating the 5th Example of this invention. It is a schematic principal part block diagram of the interference exposure apparatus for demonstrating the 7th Example of this invention. It is a schematic block diagram of the interference exposure apparatus which shows an example of a prior art.

Explanation of symbols

11a: 1st laser light source 11b: 2nd laser light source 12: Spatial filter 13: Collimating lens 14: Half mirror 15a, 15b: Mirror 16: Recording material 17: Light receiving element 18: Optical monitor control part 19: Electromagnetic shutter 20: Holographic PDLC
21: Glass substrate 22: Polymer layer 23: Liquid crystal layer 41: Light intensity modulator 51: Laser light source 52: Optical branching element 53a, 53b: Mirror 54: λ / 2 plate 55: Recording material 56: Light receiving element 60: Light intensity Modulator 71: Translucent substrate 72: Nematic liquid crystal 73: Polarizing plate 81: First diffraction grating (original diffraction grating)
82: Recording material 91: Recording material 92: Lattice area 93: Dummy area

Claims (6)

Interference fringes are obtained by splitting light emitted from a light source having coherence into a plurality of light beams and irradiating the recording material that diffracts only with one polarized light with a predetermined direction and a predetermined incident angle. In an interference exposure apparatus for producing a desired diffraction grating by exposing the recording material with the interference fringes,
The number of the plurality of light beams is M (a natural number of M ≧ 3), and (M−1) light beams are respectively combined at a predetermined direction and a predetermined incident angle to expose the recording material, and the remaining one of the light beam rotates the polarization plane by 90 degrees, the irradiated on the recording material to monitor the diffracted light intensity, when the predetermined light intensity is obtained, or, from the light source when exceeding a predetermined light intensity An interference exposure apparatus comprising a light monitor control unit that blocks light. The interference exposure apparatus according to claim 1,
An interference exposure apparatus characterized in that light emitted from the light source is branched into a plurality of light beams by a diffraction grating, and a polarization plane of zero-order light is rotated by 90 degrees . The interference exposure apparatus according to claim 1 or 2 ,
The interference exposure is characterized by irradiating the recording material with the light of the remaining one light beam with a short pulse light or with a power density smaller than the power density of the (M-1) light beams. apparatus. Recording in which light from a coherent light source is incident on the first diffraction grating, and is diffracted only by one polarized light by the interference fringes generated by the transmitted diffraction first-order light and zero-order light from the first diffraction grating. In an interference exposure apparatus for producing a desired diffraction grating by exposing a material ,
The light beam from the light source is split into two light beams, one light beam irradiates the first diffraction grating, and the other light beam irradiates the recording material after rotating the polarization vibration surface by 90 degrees, and diffracted light. An interference exposure apparatus comprising: a light monitor controller that monitors intensity and blocks light from the light source when a predetermined light intensity is obtained or exceeds a predetermined light intensity . In the interference exposure apparatus according to any one of claims 1 to 4 ,
An interference exposure apparatus using a holographic polymer dispersed liquid crystal as a recording material that diffracts only with the one polarized light . The interference exposure apparatus according to any one of claims 1 to 5 ,
An interference exposure apparatus , wherein a diffraction grating region including a dummy region of the recording material is exposed, and the monitoring light beam irradiates only the dummy region .

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