JPH10253327A - Pin hole and confocal optical apparatus using the same and apparatus and method for exposing hologram - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce diffused reflection in a glass plate by setting a thin pin hole film obtained by forming a thin film with a small hole at one face of the glass plate and an attenuation filter in the glass plate or at the other face of the glass plate. SOLUTION: A pin hole 21 is formed by layering an attenuation filter 22 and a pin hole thin film 14 on a glass plate 13. The attenuation filter 22 is placed between the glass plate 13 and the pin hole thin film 14 or at a face of the glass plate 13 opposite to the pin hole thin film 14. A reflecting light of a light projected from the pin hole 21, reflected at an optical system at the side of a lower stream than the pin hole 21 and returned to the pin hole 21 is attenuated at the attenuation filter 22, so that the reflecting light is prevented from being irregularly reflected within the glass plate constituting the pin hole 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pinhole used in an optical path, such as a confocal optical device for optically measuring the unevenness of the surface of an object, a confocal optical device using the same, an exposure apparatus for a hologram, and an exposure apparatus. It is about the method.

[0002]

2. Description of the Related Art A conventional confocal optical device using the above-described pinhole is shown in FIG. 1, and a light 2 emitted from a light source 1 is converted into an expanded parallel light by a magnifying lens device (condenser lens) 3 and projected. The light is incident on the pinhole 4 on the light side. Light passing through the pinhole 4 on the light projecting side is emitted as a point light source 5, passes through a beam splitter 6, and is condensed by a first lens group 7 and a second lens group 8, which form a telecentric system, and The measurement object 9 is irradiated. 10
Is the focal point at this time.

The light reflected on the surface of the object 9 to be measured passes through the second lens group 8 and the first lens group 7 along the same path as that at the time of incidence, and is condensed. The light is reflected by the light source 6 and is imaged at a position conjugate with the pinhole 4 on the light emitting side. A pinhole 11 on the light receiving side is arranged at this image forming position, and the light detector 12 detects the amount of light passing through the pinhole 11.

In such a confocal optical device having the conventional configuration,
When the lens groups 7, 8 or the object 9 to be measured are moved in the optical axis direction (Z direction), the point light source 5 emitted from the pinhole 4 on the light projecting side is focused on the surface of the object 9 to be measured. Shows an extreme value of the detection signal of the photodetector 12. Therefore, at this time, if the measured object 9 is scanned in the XY directions perpendicular to the optical axis, the surface shape of the measured object 9 can be measured accurately.
At this time, instead of scanning the object 9 to be measured in the X and Y directions, by using an array in which the two pinholes 4 and 11 and the photodetector 12 are two-dimensionally arranged, measurement at multiple points can be performed simultaneously. .

[0005]

The conventional confocal optical device as described above has the following problems. That is, as shown in FIG. 2, the pinhole 4 on the light projecting side used for this is made of chrome,
It is manufactured by fixing a thin film 14 for pinholes such as chromium oxide by means such as vapor deposition. Part of the light of the point light source 5 emitted from the pinhole 4 is reflected on the surface of the beam splitter 6, the lens groups 7, 8 and the surface of the pinhole 11 on the light receiving side. The reflected light repeats irregular reflection between the pinhole 4 and a portion other than the pinhole small hole 4a formed in the thin film 14 of the pinhole 4. Then, the irregularly reflected light passes through the pinhole 11 on the light receiving side, enters the photodetector 12, and is mixed with the light reflected on the surface of the object 9 to be measured, which has an adverse effect of hindering the measurement. In addition, the irregularly reflected light interferes with the point light source 5 which should be used as a confocal optical device, and generates interference fringes at the focal point 10 on the object 9 to be measured. There is.

In this case, the reflection between optical glasses such as a lens and a beam splitter can be easily reduced by means such as an anti-reflection (AR) coating.
On the pinhole surface, the reflectance is high and the coating is not easy.
It was difficult to reduce diffuse reflection in the interior.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above, and has been made in consideration of the above circumstances. A pinhole which reduces irregular reflection in a glass plate constituting the pinhole so as not to hinder optical measurement, and a confocal optical system using the same. It is an object of the present invention to provide an apparatus, a hologram exposure apparatus, and an exposure method.

[0008]

In order to achieve the above object, a pinhole according to the present invention comprises a thin film having a small hole on one surface of a glass plate, and the pinhole having the thin film and glass. With the configuration in which the neutral density filter is provided between the plates or on one of the other surfaces of the glass plate, the light transmitted through the pinhole is reflected by another optical system on the downstream side of the pinhole and is again reflected on the pinhole. Even if the light enters, the reflected light is absorbed by the neutral density filter, and the performance of the pinhole in the optical system using the pinhole can be improved.

In addition, impurities such as dyes are melted in the above-mentioned glass plate of a pinhole in which a thin film having small holes is provided on one surface of the glass plate, and this glass plate is used as a neutral density filter. Can also be used as a neutral density filter, and there is no need to separately provide a neutral density filter, which facilitates the creation of this type of pinhole.

In the above-mentioned pinhole, a window for light transmission is opened in a portion corresponding to the small hole of the pinhole of the neutral density filter, so that the dot-like light transmitted through the pinhole is reduced by the neutral density filter. Attenuation is eliminated, and damage of the neutral density filter due to the point light can be prevented.

Further, light from a light source passes through a beam splitter through a pinhole on the light projecting side, is condensed through a lens group, and irradiates the object to be measured, and the reflected light is reflected by the lens group and the beam splitter. Out of the two pinholes of the confocal optical device that is made to enter the photodetector array via the pinhole on the light receiving side through at least one of the pinholes on the light projecting side to at least one side in the light transmission direction. By configuring the confocal optical device with an optical filter interposed, reflected light reflected by an optical system such as a beam splitter on the downstream side in the transmission direction of the pinhole in the confocal optical device is reflected by the neutral density filter. The light absorbed and reflected to the pinhole side can be reduced to a level that does not hinder the measurement.

Further, a hologram exposing device for exposing the hologram by irradiating the hologram with object light through a pinhole together with a reference light is provided with a neutral density filter on at least one side of the pinhole in the light transmission direction. As a result, irregularly reflected light at the pinhole used when exposing the hologram is reduced. Therefore, it is possible to prevent light other than light from the pinhole from being recorded on the hologram.

A hologram exposed by inputting reference light and object light through a pinhole,
The reference light is made incident, the object light reproduced by this reference light is condensed and incident on the object to be measured, and the reflected light is transmitted through the hologram and incident on the photodetector array via the pinhole. By providing a dimming filter on at least one side in the light transmission direction of each of the pinholes of the confocal optical device thus configured to form a confocal optical device, the reference light is incident on the confocal optical device and When light is reproduced, when the reproduced light is incident on the photodetector array via the pinhole, light generated upstream of the optical path from the pinhole and reflected toward the pinhole is reflected by the neutral density filter. Thus, it can be reduced to a level that does not hinder the measurement.

When a hologram is created by injecting the reference light into the hologram and the object light through the pinhole, a neutral density filter is interposed on one side of the light transmission direction of the pinhole. By forming a hologram, it is possible to prevent light other than pinholes from being recorded on the hologram, and to produce a hologram with excellent performance.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to FIG. In the figure, reference numeral 21 denotes a pinhole with a dimming filter. The pinhole 21 has a configuration in which a dimming filter (ND filter) 22 and a thin film 14 for a pinhole are laminated on a glass plate 13. As shown in FIG. 3, the neutral density filter 22 includes a glass plate 13 and a thin film 1 for a pinhole.
4 or as shown in FIG.
May be laminated on the surface opposite to the thin film 14 for pinholes.

Further, as shown in FIG. 5, a glass plate 13a in which impurities such as dyes are melted in optical glass is used.
A thin film 14 for pinholes may be laminated on this. In this case, the glass plate 13a functions as a neutral density filter, and the step of bonding the neutral density filter can be omitted. In FIGS. 3 to 5, reference numeral 14a denotes a small hole that becomes a pinhole.

FIG. 6 shows an embodiment in which the pinhole 21 provided between the magnifying lens device 3 and the beam splitter 6 of the confocal optical device shown in FIG. Is shown. In this case, the neutral density filter is disposed so as to be located on the downstream side of the optical path passing through the pinhole 21.

In this embodiment, the light emitted from the pinhole 21 and reflected by the optical system downstream of the pinhole 21 and returned to the pinhole 21 side is reduced by the neutral density filter 22. The light is illuminated and irregular reflection of the reflected light in the glass plate 13 constituting the pinhole 21 is prevented.

In this embodiment, instead of the pinhole 11 interposed between the beam splitter 3 and the photodetector 12, a pinhole 21 with a dimming filter is provided, and a dimming filter is provided on the beam splitter 3 side. It may be positioned and interposed. In this case, irregular reflection of the light incident on the photodetector 12 through the pinhole 21 on the glass plates 13 and 13a of the pinhole 21 is prevented.

FIGS. 7 and 8 show an example in which the above-described pinhole 21 with a neutral density filter is used in a confocal optical device using a hologram disclosed in Japanese Patent Application Laid-Open No. 8-152308. FIG. 7 shows a state in which the hologram 25 is exposed, and the light emitted from the light source 26 is a beam splitter 27.
, And one of the lights is divided by the first magnifying lens device 28.
The hologram 2 becomes an enlarged parallel light as the reference light 29
5 is obliquely incident from below. The other light becomes enlarged parallel light by the second magnifying lens device 30 and is projected on the pinhole 21 with the neutral density filter. From each pinhole array, a point light source is projected on the first lens group 31, This allows
The hologram 25 is exposed and recorded.

After the object light is recorded on the hologram 25, as shown in FIG. 8, the light from the light source 26 'is irradiated with the reference light 29' to the hologram 25 via the magnifying lens device 28 '. The object light is reproduced on the hologram 25, and the reproduced object light 32 is transmitted to the hologram 25 as if the light equivalent thereto is as if a pinhole array of the pinholes 21 shown in FIG. Is emitted from. This is condensed by the second objective lens group 33, and is irradiated on the measured object 34 as a point light source.

The reproduced object beam 32 is the object 3 to be measured.
4, the reflected light 32 'is reflected by the second lens group 33,
The hologram 25 passes through the first lens group 31 ′, is projected on the pinhole 21, and the component passing therethrough is received by the photodetector array 35. At this time, the reproduction object beam 3
Only when the object 2 is focused on the surface of the measured object 34, the output of the photodetector array 35 becomes maximum from the principle of the confocal optical system. From this, at this time, the measured object 3
4 or by moving the second lens group 33 along the X, Y, and Z axes, the surface shape of the measured object 34 is measured.

In such a confocal optical device, by using the pinhole 21 with a neutral density filter for the pinhole, the pinhole 21 occurs between the surfaces of the first lens groups 31 and 31 'and the lower surface of the pinhole 21. Diffuse reflection can be reduced to a level that does not interfere with the measurement.

FIG. 9 shows another example of the confocal optical device shown in FIG. 8, in which a pinhole and a photodetector array 35 are separated from each other, and a relay lens 36 is interposed therebetween. I have. This is an effective technique when the pinhole cannot be brought into close contact with the pinhole due to the structure of the photodetector array 35 or the pitch of the pinhole array of the photodetector array 35 differs from that of the pinhole array. Light emitted from the pinhole is reflected between the relay lens 36 and
There is a problem that scattered light enters the photodetector array 35.

In order to solve this problem, as shown in FIG. 9, a pinhole 21 'with a dimming filter provided with a dimming filter on the upper side facing the relay lens 36 in addition to the lower side of the pinhole. Is used to reduce the irregularly reflected light on the upper side.

FIGS. 10 and 11 show another embodiment of the present invention. In FIG. 10, reference numeral 41 denotes a laser light source; 42, a first lens; 43, a pinhole; and 44, a second lens, which constitute a spatial filter and a collimator for removing a miscellaneous component of laser light.

Also in this system, the light reflected from the surface of the second lens 44 is reflected on the surface of the pinhole 43 and repeats irregular reflection to become reflected light 45 which reaches the edge of the small hole 43a of the pinhole 43. I often do. The pinhole 43 for the spatial filter is made of a very thin metal foil or the like, and there is a problem that the edge of the small hole 43a is melted by intensive irradiation of the reflected light 45. .

To solve this problem, as shown in FIG. 11, the dimming filter 22 is arranged behind the pinhole 43 to reduce the intensity of the reflected light 45. Thereby, the edge of the small hole 43a of the pinhole 43 does not melt,
The life of the pinhole 43 could be extended.

As another embodiment, as shown in FIG. 12, in order to prevent the reflected light 46 reflected between the first lens 42 and the pinhole 43 from damaging the pinhole 43, In some cases, a neutral density filter 22 is provided on the incident light side. Although not shown, the effect is still higher if the neutral density filter 22 is provided on both sides of the pinhole 43. This neutral density filter is disposed on the surface of the pinhole on which the reflected light is not incident.

In each of the embodiments described above, the example in which the neutral density filter 22 is disposed on the entire surface of the pinhole has been described. However, when the light such as laser light is strong, the neutral density filter 22 is formed by the condensed light. May be damaged, a small hole may be formed in a portion corresponding to the small hole of the pinhole of the neutral density filter 22,
Therefore, a transparent optical glass may be formed by masking in the manufacturing process of the neutral density filter. With this configuration, the point light transmitted through the pinhole is not attenuated by the neutral density filter. Further, it is possible to prevent the neutral density filter from being damaged by the point light.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a conventional confocal optical device using a pinhole.

FIG. 2 is a sectional view showing a conventional pinhole.

FIG. 3 is a sectional view showing an example of a pinhole according to the present invention.

FIG. 4 is a sectional view showing another example of the pinhole according to the present invention.

FIG. 5 is a sectional view showing another example of the pinhole according to the present invention.

FIG. 6 is an explanatory view showing a confocal optical device using a pinhole according to the present invention.

FIG. 7 is an explanatory diagram showing how a hologram of a confocal optical device using a hologram is exposed using a pinhole according to the present invention.

FIG. 8 is an explanatory diagram showing an example in which a pinhole according to the present invention is used in a confocal optical device using a hologram.

FIG. 9 is an explanatory diagram showing an example in which a pinhole according to the present invention is used in a confocal optical device using a hologram.

FIG. 10 is an explanatory diagram showing a spatial filter.

FIG. 11 is an explanatory diagram showing an example in which a pinhole according to the present invention is used for a spatial filter.

FIG. 12 is an explanatory diagram showing an example in which a pinhole according to the present invention is used for a spatial filter.

[Explanation of symbols]

 1, 26, 26 'light source 3 magnifying lens 4, 11, 14, 21, 21', 43 pinhole 4a, 14a, 43a small hole 6, 27 beam splitter 9, 34 object to be measured 12 ... Photodetectors 13, 13a Glass plate 14 Thin film 22 Light-reducing filter 25 Hologram 35 Photodetector array 41 Laser light source 42 Lens 45, 46 Reflected light

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideyuki Wakai 1200 Manda, Hiratsuka-shi, Kanagawa Prefecture, Komatsu Ltd.

Claims (7)

[Claims] 1. A light-reducing filter is provided between a glass plate and a thin film having pinholes on one surface of a glass plate, or between the thin film and the glass plate, or on the other surface of the glass plate. Pinhole. 2. A pinhole comprising a thin film having a small hole formed on one surface of a glass plate, wherein impurities such as a dye are melted in the glass plate to form a glass filter as a neutral density filter. Pinhole. 3. The pinhole according to claim 1, wherein a window for light transmission is opened in a portion corresponding to the small hole of the pinhole of the neutral density filter. 4. A light from a light source passes through a beam splitter through a pinhole on a light projecting side, is condensed through a lens group, and irradiates an object to be measured. Out of the two pinholes of the confocal optical device that is made to enter the photodetector array via the pinhole on the light receiving side through at least one of the pinholes on the light projecting side to at least one side in the light transmission direction. A confocal optical device comprising an optical filter. 5. A hologram exposure apparatus for exposing a hologram by injecting object light through a pinhole together with reference light to the hologram, wherein a light-reducing filter is provided on at least one side in the light transmission direction of the pinhole. A hologram exposure apparatus characterized by the above-mentioned. 6. A reference light is made incident, object light is made incident via a pinhole, object light is made incident on the hologram exposed, and the object light reproduced by the reference light is collected on an object to be measured. The confocal optical device is configured to transmit light, enter the light, and transmit the reflected light through the hologram to the photodetector array via the pinhole. A confocal optical device comprising a neutral density filter. 7. A hologram in which a reference beam is incident,
A hologram creation method, comprising: providing a neutral density filter on one side of a light transmission direction of a pinhole when creating a hologram by injecting object light through a pinhole.