JPH07239412A - Ir reflecting body - Google Patents

Abstract

PURPOSE:To prevent an unbalance state of colors and blur of images by attaching a hologram or a laminated body which partly reflects near infrared rays or IR rays in front of a CCD sensor. CONSTITUTION:An IR reflecting body is disposed in the incident side between an image input device C and an imaging lens L. The IR reflecting body consists of a volume hologram in which a part of near IR or IR rays in incident light which enters the image input device C is reflected or a laminated body produced by alternately laminating layers of two more kinds of materials in such a manner that the refractive indices of adjacent layers are relatively high and low.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an infrared reflector,
In particular, the present invention relates to a hologram and a laminated body for an infrared reflecting film used to prevent color balance loss and image blurring when an image is input using a CCD sensor.

[0002]

2. Description of the Related Art Conventionally, for those that reflect only infrared rays,
The following are known. A material that reflects only infrared rays by utilizing the interference of a multi-layered thin film in which a thin film is laminated on a substrate such as glass by vacuum deposition. A material that absorbs infrared rays by dispersing pigments and dyes in glass. Inorganic glass is colored with colored ions or colloids to absorb infrared light. That is, a glass infrared cut filter using an inorganic infrared absorber. As one example thereof, a near-infrared absorbing plastic film using a complex having a quaternary ammonium group as an infrared absorbing agent has been proposed (JP-A-57-21458).

An infrared absorption filter material characterized by containing at least one compound represented by the following general formula (Formula 1) has been proposed (Japanese Patent Publication No. 6-1282).
issue).

[0004]

[Chemical 1]

(In the formula, [Cat] represents a quaternary phosphonium group, M represents nickel, cobalt, copper, palladium or platinum. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ ,
R ₇ and R ₈ represent a hydrogen atom, a halogen atom or a substituted or unsubstituted alkyl group, and these may be the same or different from each other. ).

An infrared absorbing filter material characterized by containing at least one compound represented by the following general formula (Formula 2) has been proposed (Japanese Patent Publication No. 6-1283).
issue).

[0007]

[Chemical 2]

(In the formula, R ¹ , R ² , R ³ and R ⁴ may have a hydrogen atom, a halogen atom, a cyano group, a hydroxyl group, or a divalent linking group between the benzene ring to be bonded, Alkyl group, aryl group, cycloalkyl group or heterocyclic group, or R ¹ and R ² , R ² and R ³ , or R ³ and R
⁴ represents a non-metal atom group which is bonded to each other to form a 5- or 6-membered ring, and the groups R ^{1 to} R ⁴ may be the same or different. X represents an anion that neutralizes the cation in the above general formula. ).

[0009]

However, the infrared reflection films of the above items 1 to 3 have the following disadvantages. Since a vacuum system is required at the time of manufacturing, it is difficult to manufacture it in a large size, and since work efficiency is poor, mass productivity is poor and the product becomes expensive.

Since it is made of glass, it is inferior in mass productivity and the cost is high. -The type of glass used as the base material is limited to a specific type, and an arbitrary base material cannot be selected.

In order to use a semiconductor light receiving element such as a silicon photodiode (SPD) such as a CCD sensor, the light in the infrared region which is not felt by human eyes is cut off and the SPD shown in FIG. It is necessary to make the above spectral sensitivity curve state similar to the relative luminous efficiency curve. In particular, for light with a wavelength of 650 nm to 1000 nm, S
Since the output of the PD is large and the light in this area is invisible to the eyes, it causes a malfunction of the image input device such as a CCD sensor. Therefore, the visible portion has a large transmittance,
If an infrared light reflecting film that cuts off the entire infrared region of 50 to 1000 nm can be used, the light transmittance in the visible region is large and the output of the SPD is large, and therefore the performance of the image input device of the CCD sensor is significantly improved. It is clear that this is possible.

However, due to the absorption characteristics of pigments and dyes, the boundary between the infrared region to be cut and the visible region to be transmitted becomes broad, and it is difficult to cut sharply. That is, if the infrared region is sufficiently cut, a part of the visible region that is desired to be transmitted is also cut, and the transmittance is reduced. Therefore, it is necessary to take measures such as increasing the sensitivity of the SPD and correcting the output of the red sensitivity sensor. Increasing the sensitivity of the SPD leads to an increase in leak current and causes a malfunction of the photodetector, which is a problem. If the color correction is insufficient, there are problems that the image is dark, the color balance of the image is lost, and the image is blurred.

Although it is relatively robust against heat and light, it has the drawback of low light transmittance in the visible region, and as described above, it has poor operating performance, dark images, and loss of color balance. However, there are problems such as occurrence of image blurring and necessity of troublesome color correction.

Since it is an inorganic substance, it lacks flexibility in terms of manufacturing and it is difficult to improve the manufacturing process.・ Manufacturing cost is high, and the cost of the device will be greatly increased. -Furthermore, a near-infrared absorbing plastic film using a complex having a quaternary ammonium group as an infrared absorbing agent is insufficient in solubility of the infrared absorbing agent in an organic solvent, so that a thin plastic film cannot be produced. That is, in order to produce a thin film with good infrared absorption efficiency, a large amount of infrared absorbent must be dispersed in the resin, and an infrared absorbent having a small solubility in an organic solvent satisfies the purpose. I can't. -Furthermore, near-infrared absorbing plastics that use a complex having a quaternary ammonium group as an infrared absorbing agent have poor heat resistance and light resistance.

Since the boundary between the infrared region to be cut and the visible region to be transmitted becomes broad, it is impossible to perform sharp cutting, and as described in the above, there is a decrease in operation performance, a dark image, a loss of color balance, and an image. There are problems such as occurrence of blurring and necessity of troublesome color correction.

The present invention has been made to solve the above problems of the prior art, and its object is to provide a CCD sensor used in a video camera or the like with sensitivity to near infrared rays. If you use it as it is, the image becomes dark, the color balance is lost, the image is blurred, or uniform noise is generated.Therefore, attach a hologram or laminated body that reflects near infrared rays or part of infrared rays in front of the CCD sensor. Another object of the present invention is to provide an infrared reflector that prevents color balance loss and image blurring, and, unlike conventional products, offers the following advantages.

A vacuum system is not required at the time of manufacturing, and the manufacturing is easy. The base material can be freely selected according to the intended use, and can be formed into a film, for example. (It can be produced by winding on a film substrate and then attached to a desired substrate.) Since it can be produced by continuous winding exposure on a film substrate, mass production can be achieved and cost can be reduced. The boundary between the infrared wavelength region to be reflected and the visible wavelength region to be transmitted can be sharply cut by adjusting the sensitizing dye concentration, the film thickness of the photosensitive material and the like. Therefore, the light transmittance in the visible region is large, and it is not necessary to increase the sensitivity of SPD.
No worries about malfunctions. Further, it is possible to obtain a bright and clear image with good color balance without the need for complicated correction such as color correction. Further, the wavelength to be reflected can be easily controlled by adjusting the laser incident angle during recording or adjusting the film thickness of one layer of the laminate.

[0018]

In order to achieve the above object, in the present invention, for example, Japanese Patent Application No. 5-194540.
By using the hologram recording method disclosed in Japanese Patent Application No. Hei 5-225616, a long recording film is transferred and exposed by a linear light beam, so that a large area and a high level of evenness can be obtained. A volume hologram that reflects near-infrared rays or a part of infrared rays of high quality is mass-produced with high yield. The large-area hologram thus produced is cut into a size necessary for an image input device such as a CCD sensor to form an infrared reflection hologram F, which is connected to an image input device C such as a CCD sensor as shown in FIG. It is installed between the image lens L and the image lens L.

Further, in the present invention, JP-A-5-28
No. 8910, a layered product constituted by alternately layering layers made of two or more materials that reflect near infrared rays or a part of infrared rays so that the refractive index becomes relatively high and low. The cutting is performed in the same manner as described above, and the cutting is performed between the image input device C and the imaging lens L.

Some image input devices use a spatial frequency filter, which is made of a relief type diffraction grating or a crystal plate such as a crystal plate for preventing moire fringes. When such a spatial frequency filter SF is used, as shown in FIG. 2, even if the spatial frequency filter SF is manufactured on a substrate different from the infrared reflection hologram or the laminated body F and is inserted in the optical path separately. Often ((a) and (b) in the figure), the infrared reflection hologram or laminated body F and the spatial frequency filter SF may be produced on one substrate, and the spatial frequency filter SF and the infrared reflection hologram or laminated body. Alternatively, Fs may be attached and integrated into the optical path ((c) in the figure).

That is, the infrared reflector of the present invention is disposed on the incident side of the image input device and is configured to reflect a part of the wavelength of near infrared light or infrared light of the incident light incident on the image input device. It is characterized by comprising a hologram or a laminated body in which layers made of two or more kinds of materials are alternately laminated so that the refractive index is relatively high and low.

In this case, it is preferable that the near-infrared ray or a part of the wavelength of the infrared ray of the incident light entering the CCD camera is reflected. Further, it may be arranged in combination with a spatial frequency filter.

Specifically, this reflector is composed of, for example, a volume hologram, and can be constructed so that the film thickness is 5 to 100 μm and the refractive index modulation is 0.02 to 0.25.

Further, it is desirable that the reflectance characteristic reflects a part of the light having a wavelength of around 600 nm to 1000 nm. As for the transmittance characteristic, it is desirable that the transmittance at a wavelength of 600 nm is 70% or more and the transmittance at a wavelength of 650 nm is 20% or less. Further, a plurality of volume holograms having different peak reflectance wavelengths in the range of 600 nm to 1000 nm and having a half width of 35 nm or more can be bonded together.

This infrared reflector has a reflectance peak wavelength of 900 ± 100 nm and a half width of 300 ± 100.
The volume hologram with the characteristic of nm and the peak wavelength is 700 ±
A volume hologram having a 100 nm and a half-value width of 200 ± 100 nm may be bonded together, and the peak wavelength of the reflectance may be 900 ± 100 n.
m, a volume hologram having a half width of 300 ± 100 nm,
Peak wavelength is 600 ± 100nm, half-width is 100nm
It is also possible to compose two or more of the following volume holograms.

It is desirable that the slope of the transmittance curve on the short wavelength side of this infrared reflector satisfies the following equation. 0.85 ≦ 50 / {(wavelength (nm) with 20% transmittance) −
(Wavelength (nm) with a transmittance of 70%)}.

[0027]

In the present invention, the volume hologram or the volume hologram constructed so as to reflect a part of the wavelength of near infrared rays or infrared rays of the incident light incident on the image input device on the incident side of the image input device such as a CCD camera or the like. Since a laminated body in which layers made of two or more kinds of materials are alternately laminated so that the refractive index is relatively high and low, the infrared wavelength to be reflected and the visible wavelength to be transmitted are set. Can be made sharper, there is no need to improve the sensitivity of the semiconductor light receiving element such as SPD of the image input device, and complicated correction of the sensor output such as color correction is not required, and the color balance at the time of image input is destroyed. It is possible to obtain a bright and clear image that prevents blurring of the image. The wavelength to be reflected can be easily controlled only by changing the laser incident angle at the time of recording the volume hologram or changing the laminated film thickness of the laminated body. Further, since it can be produced in the form of a film, it can be mass-produced and can be produced at a lower cost than conventional products.

[0028]

【Example】

Example 1 A hologram produced as follows
As shown in FIG. 1, when the reflector F is installed between the CCD sensor C and the imaging lens L, it is brighter, has a better color balance, and is more blurred than the case where a conventional color correction glass or an optical filter material is used. No clear image was obtained.

A composition having the following chemical formula 3 was dissolved in 14.49 g of chlorobenzene and filtered with a filter having a pore size of 0.25 μm to obtain a photosensitive solution.

[0030]

[Chemical 3]

A PET film (Teijin Co., Ltd .: HP-7) having a thickness of 50 μm and having been subjected to an inner surface primer treatment was prepared using this photosensitive solution.
The film thickness is 10μ after drying using a roller coater.
m, and dried at 70 ° C. for 10 minutes,
Polyvinyl alcohol (Kuraray Co., Ltd. PVA205
A 5% aqueous solution having a polymerization degree of 500 and a saponification degree of 88%) was applied with a roller coater. This was dried at 60 ° C. for 10 minutes to obtain recording film 2 in FIG.

Next, FIG. 3 is a perspective view, and FIG. 4 is a line A in FIG.
As shown in the cross-sectional view taken along the line -A ', only the surface 5 in contact with the recording film 2 is a convex curved surface, and the surface 6 on which light is incident and the surfaces other than the convex curved surface 5 are black and are subjected to an antireflection treatment. 3, the recording film 2 in the state as shown in FIG.
Is a polyvinyl alcohol coated surface on the lower side and PET on the upper side
On the film substrate side, as the index matching liquid 4, bromobenzene (refractive index 1.56) is used to bring the refractive index closer to the recording film 2, and a block made of polyester resin (refractive index 1.57) is used. 3, the light 11 having a wavelength of 647 nm emitted from the Kr laser was used, and the light intensity was 50 mW / cm ² at an angle of θ = 45.8 °.
The recording film 2 is continuously supplied at a speed of 5 cm / sec, and the interference between the incident light from the glass block 3 and the totally reflected light on the rear surface of the recording film 2 causes an interference parallel to the film surface. Stripes were recorded on recording film 2.

After the exposure, the recording medium was washed with water in a running water bath for 1 minute to remove the polyvinyl alcohol layer and dried.

Next, the recording film 2 was taken out by immersing it in a methyl isobutyl ketone 21 ° C. bath for 2 minutes and then in a heptane bath for 5 seconds.

The diffraction efficiency of the hologram thus obtained was measured and found to be 1% at 81% at a wavelength near 650 nm.
It was 58% at a wavelength of 000 nm. That is, a diffraction grating having interference fringes recorded in a direction substantially parallel to the recording layer of the recording film 2 and having a reflectance from 650 nm to 1000 nm of about 60% or more was obtained. This value was uniform within the range of ± 3% at any part of the recording film 2.

In the above, the refractive index values are those of the sodium D line measured by Abbe's refractometer.

The diffraction efficiency at this time was measured by cutting the recording film after the formation of interference fringes into a size of about 5 cm square, and using a spectrophotometer manufactured by Shimadzu Corporation (Shimadzu double monochromator self-recording spectrophotometer). UV-365) 1
The transmittance for vertically incident light in the range of 400 nm to 400 nm was measured, and the value obtained by subtracting this transmittance from 100% was regarded as the reflectance, that is, the diffraction efficiency.

The transmittance curve of this example is shown in FIG. For comparison with this, the transmittance curve of the conventional infrared absorbing filter material of Japanese Patent Publication No. 6-1282 is shown in FIG. From the comparison between the two, according to the infrared reflector according to the present invention, the boundary between the infrared region to be cut and the visible region to be transmitted,
It becomes much steeper than in the prior art, and even if the infrared region is sufficiently cut, the visible region desired to be transmitted is not cut, and the transmittance is not lowered.

The light intensity of the laser light at the time of recording at this time was measured by applying a power meter (model 200 power meter manufactured by Coherent Co., Ltd.) perpendicularly to the incident beam 11 before the block 3. This is a value converted into the light intensity actually radiated on the recording film 2 in consideration of the incident angle θ (light intensity on the recording film 2 = scale of power meter × sin θ).

In FIG. 3, 9 indicates a linear exposure region, and 10 indicates an incident region of the incident surface 6 on which the linear incident light flux 11 is incident. In order to form such a linear incident light beam 11, for example, as shown in FIG. 7, a concave flat cylindrical lens 14 in which a thin laser beam 13 is confocally arranged.
It may be enlarged in one direction through the convex flat cylindrical lens 15.

By the way, in this embodiment, as shown in FIG. 8, a similar transparent incident body 3 may be arranged below the recording film 2. In FIG. 8, as in FIG.
Since the surface 5 in contact with the recording film 2 has a convex cylindrical shape, the recording film 2 is wound around the glass block 3 via the index matching liquid 4,
If the recording film 2 presses the glass block 3 from above with the rolls 1 upstream and downstream of the glass block 3, the block 3 and the recording film 2 have good adhesiveness, and unnecessary stray light can be removed, thus ensuring good quality. You can create things. Also in this case, it is preferable to perform light absorption processing on the surfaces of the glass block 3 other than the light flux incident surface 6 and the contact surface 5.

Example 2 Example 1 was repeated except that the addition amount of the squarylium dye used as the sensitizing dye in Example 1 was adjusted so that the absorbance Abs was about 1.0.
A photosensitive solution was obtained in the same manner as in. Then, in the same manner as in Example 1, a recording film 2 was obtained.

Then, in the same manner as in Example 1, the recording film 2 was brought into close contact with the block 3, and light having a wavelength of 647 nm emitted from a Kr laser was used at an angle of θ = 29 ° and a light intensity of 65 mW / cm. ^The recording film 2 was made incident at ² , and the recording film 2 was continuously supplied at a speed of 5 cm / sec to record interference fringes on the recording film 2. Then, in the same manner as in Example 1, after removing the polyvinyl alcohol, the development was performed in the same manner as in Example 1 except that the temperature of methyl isobutyl ketone was changed to 23 ° C.

The hologram thus obtained has a diffraction efficiency of 88% at a wavelength near 1000 nm and a half width of 200.
was nm. On the other hand, the incident angle of the laser beam 11 is θ =
As a result of being manufactured in the same manner as described above except that the light intensity was changed to 37.3 ° and the light intensity was changed to 52 mW / cm ² , the diffraction efficiency was 80.
A hologram having 94% at a wavelength near 0 nm and a full width at half maximum of 250 nm was obtained.

The two kinds of holograms thus produced having different wavelengths were placed at 120 ° C. through an EVA film (Dumilan film 50 μm thick manufactured by Takeda Pharmaceutical Co., Ltd.) between them.
Stacked under heated roller. A hologram having a diffraction efficiency of about 80% or more was obtained in the wavelength range of 650 nm to 1000 nm. The measurement of the diffraction efficiency was performed in the same manner as in Example 1.

The hologram thus obtained was placed between the CCD sensor and the imaging lens as in the case of Example 1, and was brighter than that of the conventional optical filter material of color correction glass or the like and had a color balance. A good, clear image with no blur was obtained.

Example 3 The same as Example 1 except that the incident angle was changed to θ = 32.6 ° and the light intensity was 58 mW / cm ² on the recording film 2 produced in the same manner as in Example 1. After recording the interference fringes and developing the same as in Example 1, the diffraction efficiency was measured. As a result, a hologram having a diffraction efficiency of 91% and a half width of 350 nm near a wavelength of 900 nm was obtained.

Next, instead of the recording film of Example 1, a film made by DuPont (Omnidex 352, roll film having a width of 1 foot and a length of 500 feet) was used as the recording film 2, and xylene was used as the index matching liquid 4. 7, the light 13 having a wavelength of 514 nm emitted from the Ar laser is made incident on the concave surface of the concave plano cylindrical lens 14, and then made incident on the convex surface of the convex plano cylindrical lens 15 as shown in FIG. The slit-shaped parallel light 11 by θ = 52
Light intensity 60 to 7 from the surface 6 of the glass block 3 at an angle of °
It was incident at 5 nm / cm ² .

The recording film 2 is continuously 0.5
When supplied at a speed of cm / sec, interference fringes were recorded on the recording film 2 and the diffraction efficiency was 80 at around 650 nm.
%, A hologram having a sharp peak with a half value width of 40 nm was obtained.

The two kinds of holograms thus obtained are
Stacking was performed in the same manner as in Example 2. As a result of measuring the diffraction efficiency, a diffraction efficiency that sharply rises at a wavelength of 650 nm was obtained, and a diffraction efficiency of about 80% or more was obtained in the wavelength range of 650 nm to 1000 nm.

The hologram thus obtained was placed between the CCD sensor and the imaging lens as in the first embodiment. The hologram was brighter and had a better color balance than the conventional color correction glass or optical filter material. A clear image without blur was obtained.

Example 4 Polyvinylidene chloride film (25 μm thick, refractive index 1.62) and polyvinylidene fluoride film (25 μm thick, refractive index 1.4)
2) was subjected to a stretching treatment in a heating atmosphere, and 21.4 μm, 23.0 μm, 24.6 μm, 2
6.3 μm, 28.0 μm, 29.6 μm, 31.3 μm
A film having a thickness of m and a film thickness of 32.9 μm and having various thicknesses was obtained.

First, a total of 30 films, 15 films each having a thickness of 21.4 μm, were laminated alternately so that the refractive indexes were high / low / high / low, and dry lamination was performed while heating. went. Sequentially 23.0μm, 24.6μ
m, 26.3 μm, 28.0 μm, 29.6 μm, 3
Lamination was similarly performed using a film having a thickness of 1.3 μm and a thickness of 32.9 μm.

The eight laminations thus produced were further stretched and stretched 100 times to reduce the thickness to 1/100. These eight stretched films each have a diffraction characteristic as shown in FIG. 9, and by laminating these eight sheets as shown in the cross section in FIG. 10 and performing dry lamination, the results are shown in FIG. As described above, it was possible to manufacture a diffraction grating (laminate) having a smooth diffraction characteristic in the wavelength range of approximately 650 nm to 1000 nm.

The laminated body thus obtained was placed between the CCD sensor and the imaging lens in the same manner as in Example 1. As a result, the color balance was brighter than that of the conventional color correction glass or optical filter material. A clear image with good blur and no blur was obtained. The infrared reflector of the present invention has been described above based on some embodiments, but the present invention is not limited to these embodiments and various modifications can be made.

[0056]

As is apparent from the above description, according to the infrared reflector of the present invention, near infrared rays or infrared rays of incident light incident on the image input device are incident on the incident side of the image input device such as a CCD camera. A volume hologram arranged to reflect a part of the wavelength or a laminated body in which layers made of two or more kinds of materials are alternately laminated so that the refractive index becomes relatively high and low is arranged. Therefore, the boundary between the infrared wavelength to be reflected and the visible wavelength to be transmitted can be made sharp, it is not necessary to improve the sensitivity of the semiconductor light receiving element such as SPD of the image input device, and the sensor output for color correction is complicated. It is possible to obtain a bright and clear image in which the color balance is prevented from being lost and the image is not blurred at the time of image input, without any need for correction. The wavelength to be reflected can be easily controlled only by changing the laser incident angle at the time of recording the volume hologram or changing the laminated film thickness of the laminated body. Further, since it can be produced in the form of a film, it can be mass-produced and can be produced at a lower cost than conventional products.

[Brief description of drawings]

FIG. 1 is a diagram showing how an infrared reflector of the present invention is installed in an image input device.

FIG. 2 is a diagram showing a combination state of an infrared reflector and a spatial frequency filter.

FIG. 3 is a diagram showing an arrangement of the hologram recording device used in Example 1.

4 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 5 is a diagram showing transmittance characteristics of Example 1.

FIG. 6 is a diagram showing one transmittance characteristic of a conventional technique.

FIG. 7 is a diagram showing an example of an optical system for forming a linear light beam.

FIG. 8 is a diagram showing another arrangement of the hologram recording device used in the first embodiment.

9 is a diagram showing diffraction characteristics of each lamination film of Example 4. FIG.

FIG. 10 is a cross-sectional view of a laminate of Example 4.

FIG. 11 is a diagram showing diffraction characteristics of the laminate of Example 4.

FIG. 12 is a diagram showing a spectral sensitivity curve and a relative luminous efficiency curve of SPD.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Roll row 2 ... Recording film 3 ... Transparent incident body 4 ... Index matching liquid 5 ... Adhesive surface of transparent incident body 6 ... Incident surface of transparent incident body 7 ... Other surface of recording film 8 ... Supply nozzle 9 ... Linear Exposure area 10 ... Incident area 11 ... Incident light flux 12 ... Reflected light flux 13 ... Laser light 14 ... Concave flat cylindrical lens 15 ... Convex flat cylindrical lens 21 ... High refractive index film (0.214 μm) 22 ... Low refractive index Film (0.214 μm) 23 ... High refractive index film (0.23 μm) 24 ... Low refractive index film (0.23 μm) 25 ... High refractive index film (0.329 μm) 26 ... Low refractive index film (0.329 μm) F ... Infrared reflection hologram or laminated body C ... Image input device L ... Imaging lens SF ... Spatial frequency filter

Claims (10)

[Claims] 1. A volume hologram or two or more kinds of materials arranged on the incident side of an image input device and configured to reflect a part of near infrared rays or infrared wavelengths of incident light entering the image input device. An infrared reflector comprising a laminated body in which the layers are alternately laminated so that the refractive indices are relatively high and low. 2. The infrared reflector according to claim 1, wherein the infrared reflector is configured to reflect a near infrared ray or a part of an infrared ray wavelength of incident light entering a CCD camera. 3. The infrared reflector according to claim 1, which is arranged in combination with a spatial frequency filter. 4. The reflector comprises a volume hologram,
The film thickness is 5 to 100 μm, and the refractive index modulation is 0.02 to
It is 0.25, The infrared reflector of any one of Claim 1 to 3 characterized by the above-mentioned. 5. The reflectance characteristic is from about 600 nm to 10
The infrared reflector according to any one of claims 1 to 4, which reflects a part of light having a wavelength of up to 00 nm. 6. The infrared reflector according to claim 5, wherein the transmittance has a transmittance at a wavelength of 600 nm of 70% or more and a transmittance at a wavelength of 650 nm of 20% or less. 7. The peak wavelength of reflectance is 600 nm to 10 nm.
The infrared reflector according to claim 5, wherein a plurality of volume holograms each having a half width of 35 nm or more, which are different in the range of 00 nm, are stuck together. 8. The peak wavelength of reflectance is 900 ± 100 n
m, a volume hologram having a characteristic of a half width of 300 ± 100 nm, a peak wavelength of 700 ± 100 nm, and a half width of 20
4. A volume hologram of 0. +-. 100 nm including two pieces bonded together is included.
Infrared reflector according to the item. 9. The peak wavelength of reflectance is 900 ± 100 n.
m, a volume hologram having a half width of 300 ± 100 nm,
Peak wavelength is 600 ± 100nm, half-width is 100nm
The infrared reflector according to any one of claims 1 to 3, which is formed by laminating two or more of the following volume holograms. 10. The inclination of the transmittance curve on the short wavelength side satisfies the following expression: 1.
Item Infrared reflector: 0.85 ≦ 50 / {(wavelength (nm) with 20% transmittance) −
(Wavelength (nm) with a transmittance of 70%)}.