JPH06313857A - Image i/o device using hologram - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a drop in the sensitivity of an image receiving device by minimizing the reduction of a light quantity at the time of reading a color image. CONSTITUTION:This device has a hologram 2 capable of diffracting image light 1 spectroscopically into R (red), G (green) and B (blue) components, and focusing each component, and an image receiving section 3 where R, G and B sensitive picture elements are laid cyclically. Also, the image light 1 is spectroscopically diffracted through the hologram 2 and inputted to a corresponding light sensitive picture element. As a result, the light 1 does not need to pass a color filter, and no absorption loss occurs and diffracted light can be efficiently focused at the predetermined position. Thus, each wavelength component can be employed without any waste, and the utilization efficiently of the component can be substantially increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a C using a hologram.
The present invention relates to an image input / output device such as a CD camera.

[0002]

2. Description of the Related Art Conventionally, in a color image input / output device, a color filter has been used for spectral separation into R (red), G (green) and B (blue) colors. In this input / output device, an image to be photographed is formed on an image receiving portion such as a CCD by an image forming lens, but the wavelength of light transmitted through each pixel is selected by an R, G, B color filter before image formation. is doing.

However, in the conventional color image input / output device using the color filter, since the light transmitted through the color filter is selected, the color component transmitted through the color filter is limited to one color. The complementary color component of is wasted, and there is a loss due to absorption in each color filter, and the amount of light is greatly reduced. As a result, there is a problem that the sensitivity of the image receiving apparatus (camera) as a whole is lowered.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and uses a hologram capable of preventing a decrease in light amount when reading a color image and preventing a decrease in sensitivity of an image receiving device. An object is to provide an image input / output device.

[0005]

As shown in FIG. 1, an image input / output device using a hologram of the present invention converts an incident image light 1 into R, G, B colors for each pixel using a hologram 2. It is characterized in that it is spectrally diffracted and the diffracted light 4 is input to the R, G, B pixels of the image receiving unit 3 corresponding to each R, G, B pixel.

[0006]

In the present invention, in order to extract color components in units of a set of R, G, and B pixels (hereinafter referred to as picture element units) as a light input method, the spectral and condensing functions of holograms are used. It is possible to suppress the decrease in the amount of light as much as possible, and as a result, it is possible to prevent the sensitivity of the image receiving device from decreasing.

[0007]

The image input / output device using the hologram of the present invention will be described in more detail below with reference to the drawings.
FIG. 2 is an explanatory diagram when a hologram produced by triple recording or laminating three sheets is used. In FIG. 2, a transmission hologram 2'is arranged on the image light incident side of the image receiving unit 3. In this case, the transmissive hologram 2 ′ is formed by superimposing three holograms 21 to 23 or is formed by multiplex recording three times, and the three holograms forming one picture element of the image receiving unit 3 are formed. Each array of R, G, and B pixels is arranged in an array at the same pitch as the pixels. In this case, the transmissive hologram 2 ′, whether it is made of multiple recording or three recordings of one time recording, is either a predetermined wavelength component in the image light incident at a predetermined angle with respect to the hologram surface. It is formed into a Fresnel zone plate shape having wavelength and angle selectivity so that only the light having the selected wavelength is selectively diffracted and the wavelength light is condensed to the corresponding R, G, and B pixels of the image receiving unit 3. Here, the transmission hologram having wavelength and angle selectivity is a type in which only a specific wavelength is diffracted and other wavelengths are transmitted without being diffracted, like a Lippmann hologram. The red wavelength component in the image light that is substantially perpendicularly incident on the hologram surface of each unit hologram is selectively diffracted by the red hologram 21 of the transmission hologram 2'or the red hologram in the multiple recording, and the red wavelength component of the pixel R of the pixel R. It is focused on the position. Similarly, the green wavelength component in the image light is selectively diffracted by the green hologram 22 of the transmissive hologram 2'or the green hologram in the multiple recording, and the blue wavelength in the image light is located at the position of the pixel G. The wavelength component is selectively diffracted by the blue hologram 23 of the transmissive hologram 2'or the blue hologram in the multiple recording and is condensed at the position of the pixel B, respectively. The image receiving unit 3 is composed of a CCD or the like, and the positions of R, G, and B pixels are determined in advance, so that the incident image light of each color can be converted into an electric signal and read.

As described above, by utilizing the wavelength and angle selectivity of diffraction by each component hologram of the hologram 2 ', R of the image receiving portion 3 in which only three specific wavelength components are arranged on the exit side of the hologram 2', The wavelength components of the colors corresponding to the G and B pixels are diffracted and made to enter, whereby the respective wavelength components can be made to directly enter the image receiving portion without waste, so that the utilization efficiency can be greatly improved. .

FIG. 3 is an explanatory diagram when one dispersion hologram is used. In FIG. 3, for example, the transmission hologram 2 is arranged on the incident side of the image light 1 of the image receiving unit 3 which is formed by repeating three adjacent R, G, and B pixels. The transmissive hologram 2 includes three Rs that form one picture element of the image receiving unit 3,
The unit holograms are arranged in an array at the same pitch as the G and B pixels, and each unit hologram diffracts white light that is incident almost perpendicularly to the hologram surface and is offset from the corresponding unit hologram. It is formed in a Fresnel zone plate shape so as to collect light on the pixels of the image receiving unit at the above positions. As the hologram 2, a relief type, a phase type, an amplitude type, or the like that has little or no wavelength dependence of diffraction efficiency is used. Here, the wavelength efficiency of the diffraction efficiency has no or little dependence is of a type (diffraction wavelength and angle-selective hologram) that does not diffract other wavelengths, such as a Lippmann hologram. It does not mean a single diffraction grating that diffracts any wavelength, and this diffraction grating having a small wavelength dependence generally diffracts at different diffraction angles depending on the wavelength. Therefore, the diffraction angles of the unit holograms differ depending on the wavelength of the image light 1, and the focusing positions for each wavelength are dispersed in the direction parallel to the surface of the hologram 2. Therefore, the red wavelength component of the image light 1 is diffracted and condensed at the position of the image receiving portion R, the green component is diffracted at the position of the image receiving portion G, and the blue component is diffracted at the position of the image receiving portion B. The image receiving unit 3 is composed of a CCD or the like, and the positions of R, G, and B pixels are determined in advance, so that the incident image light of each color can be converted into an electric signal and read.

As described above, by utilizing the difference in the diffraction angle depending on each wavelength of the hologram 2, the wavelength component of the display color corresponding to each pixel R, G, B of the image receiving portion 3 arranged behind the hologram is diffracted. The wavelength components can be directly incident on each pixel of the image receiving unit without waste, and the utilization efficiency can be significantly improved. 2 and 3, the image light is made to enter the hologram surface almost perpendicularly, but it is also possible to make the light incident at a predetermined angle with respect to the normal line of the hologram surface. .

By the way, in FIGS. 2 and 3, a Fresnel zone plate-shaped micro-hologram array for wavelength dispersion is arranged in alignment corresponding to each set of R, G and B of the image receiving portion. However, by combining a uniform hologram that acts as a diffraction grating that has a wavelength-dependent wavelength dispersion and a microlens array, the wavelength-dispersion function of the hologram is also used to significantly improve the light utilization efficiency. Can be made. To do so, as shown in FIG.
A microlens array 7 having microlenses 5 having a diameter corresponding to the pixel pitch of the image receiving section 3 provided on a glass substrate 6 is arranged on the front surface of the image receiving section 3, and the microlens array 7 is uniformly arranged on the image receiving section 3 side. The transmission hologram 2 having a small wavelength dependence and formed of various interference fringes is integrally provided. According to this structure, the image light 1 condensed by the microlens 5 is diffracted by the transmissive hologram 2 at different angles depending on the wavelength and is dispersed. Therefore, as in the case of FIG. 2 and FIG. 3, the condensing position for each wavelength is dispersed in the direction parallel to the hologram 2 surface, the red wavelength component of the image light 1 is at the position of the pixel R, and the green component is at the pixel R. The blue component is condensed at the position of G and is read at the position of pixel B. In this configuration, since it is possible to use, as the hologram 2, a transmission type hologram having uniform wavelength fringes, which is not light-condensing and has little wavelength dependence, it is not necessary to align the hologram 2 with the image receiving unit 3.

In the case of FIG. 2, the transmission hologram 2'having wavelength and angle selectivity is formed by superimposing three holograms 21 to 23 diffracting on three different wavelengths, or three times. Although it is formed by multiple recording, it may be formed by two wavelengths. FIG. 5 shows the configuration in that case. In this case, a uniform hologram that acts as a diffraction grating having wavelength and angle selectivity is combined with a microlens array, and the wavelength and angle selectivity of diffraction are utilized in the same manner as in FIG. In FIG. 5, a microlens 5 having a diameter corresponding to the pixel pitch of the image receiving portion is provided on the glass substrate 6 on the front surface of the image receiving portion 3 in FIG. An array 7 is arranged, and a blue hologram 2 composed of uniform interference fringes having wavelength and angle selectivity is provided on the image receiving portion 3 side of the microlens array 7.
3. The hologram for red 21 is integrally provided. According to this structure, most of the blue wavelength component in the image light 1 collected by the microlens 5 is the blue hologram 2.
3, the light is condensed at the position of the pixel B, most of the red wavelength component is diffracted by the hologram for red 21 and condensed at the position of the pixel R, and the green component not diffracted by the hologram 2 '. Goes straight through the holograms 23 and 21 and is focused at the position of the pixel G. Therefore, the image light 1
, The red wavelength component is condensed at the position of the pixel R, the green component is condensed at the position of the pixel G, and the blue component is condensed at the position of the pixel B.
Read. In this configuration, the hologram 21,
Since a hologram having uniform wavelength and angle selectivity, which has no condensing property, can be used as 23, it is not necessary to align the holograms 21 and 23 with the image receiving section 3.

In FIG. 5, even if the microlens 5 is omitted and the hologram is not provided with a light condensing function, the red diffracted light and the blue diffracted light are diffracted without being condensed. G light as a complementary color can be made incident on the pixel G of. However, in this case, image blurring occurs, and therefore, when the microlens 5 is omitted, it is desirable that the hologram has a condensing function.

Here, one concrete example will be shown. As a hologram photosensitive material, a photopolymer-based Omnipond 352 manufactured by DuPont is used, and as a laser, a spectrophysic Argon ion laser output 5 W, wavelength 514 is used.
nm was used. First, a specific example of the optical system shown in FIG. 2 will be described. In this optical system, a transmissive hologram is triple-exposed in one photosensitive material, or a transmissive hologram that selectively diffracts R, G, and B colors is recorded on each of the three photosensitive materials. At this time, it is necessary for the hologram to have sufficient wavelength selectivity, and for that purpose, the film thickness of the photosensitive material and the angle of the diffracted light are important factors.

The light-sensitive material used this time was a photopolymer-based Omnidex 352 manufactured by DuPont. The thickness of the light-sensitive material was 40 μm, and the diffraction angle of the optical system was 45 ° from the vertical. Spectra Physics Argon Ion Laser, Model SP-2020-
055, output 5 W, wavelength 514 nm was used in a single mode state with current 30 A and output 0.1 W. In this example, the triple recording method was used. The light-sensitive material was photographed a total of three times for R, G and B under the following exposure conditions. (Recording conditions) Exposure intensity: 1.0 mW / cm ² Shooting time: 40 sec Exposure amount: 40 mJ / cm ² Exposure area: 300 × 300 μm (shooting optical system) For blue: Reference light −4.5 °, parallel light ∞ Object Light + 45.4 °, divergent light f = 1.41 mm For green: reference light −0.5 °, parallel light ∞ object light ± 0 °, divergent light f = 1.0 for red: reference light + 2.5 °, Parallel light ∞ Object light + 39.8 °, divergent light f = 1.30 mm Post-treatment condition) UV irradiation: 10 minutes, 100 mJ / cm ² heat treatment: 120 ° C., 2 hours Metal halide lamp for hologram that has undergone the above steps, When white parallel light generated by combining Iwasaki Electric Co., Ltd. and a parabolic mirror was irradiated, it was confirmed that the three colors R, G and B were dispersed and diffracted at the desired position and direction. did it.

Next, this hologram is formed into an array, and C
It was confirmed whether an image could be input by combining it with a CD. First, the hologram lens array was formed by repeating the above exposure. When this hologram array is attached to the front surface of the CCD, an image can be input when the image is taken, and the amount of light incident on the CCD is improved by about 3 times compared to when the hologram array is not used. Was confirmed, and the sensitivity was improved by the present invention.

Next, a specific example in the configuration of FIG. 3 will be described. In this case, there is only one photosensitive material,
Only once. The angle and focal length of white light diffracted by a hologram change depending on its wavelength. The recording conditions and post-processing conditions are the same as in the case of triple exposure. The taking optical meter is as follows. Object light: Angle 0.5 °, parallel light Reference light: Angle 31.7 °, focal length 1.18 mm For the hologram that has undergone the above steps, a metal halide lamp, manufactured by Iwasaki Electric Co., Ltd., and a parabolic mirror are combined. It was confirmed that the three colors of R, G and B were spectrally diffracted and diffracted at a desired position and direction when irradiated with white parallel light generated by the above.

Next, this hologram is formed into an array, and C
It was confirmed whether an image could be input by combining it with a CD. First, the hologram lens array was formed by repeating the above exposure. When this hologram array is attached to the front surface of the CCD, an image can be input when the image is taken, and the amount of light incident on the CCD is improved by about 3 times compared to when the hologram array is not used. Was confirmed, and the sensitivity was improved by the present invention.

As a duplication method, both of the above are 1
If a hologram lens array is formed on the entire surface, a new photosensitive material can be used as a master plate and a new photosensitive material can be brought into close contact therewith, and reproduction light can be incident from the master plate side for easy duplication.

[0020]

As is apparent from the above description, according to the present invention, the incident light is diffracted and separated by the hologram, and the light having different wavelengths is emitted to a desired position in a predetermined spatial cycle. You do n’t have to pass
There is no loss due to absorption and bright imaging is possible.
In addition, since the light that has been dispersed efficiently can be condensed at a predetermined position, each wavelength component can be used without waste, and the utilization efficiency thereof can be significantly improved.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the principle of an image input / output device using a hologram.

FIG. 2 is an explanatory diagram in the case of using a triple recording or a three-piece bonded hologram.

FIG. 3 is an explanatory diagram when a single-dispersion hologram is used.

FIG. 4 is an explanatory diagram when a microlens array is combined with the configuration of FIG.

5 is a diagram showing a modified configuration of FIG.

[Explanation of symbols]

1 ... Image light, 2 ... Hologram, 3 ... Image receiving part, 4 ... Diffracted light, 5 ... Microlens, 6 ... Glass substrate, 7 ... Microlens array, 21 ... Red hologram, 22 ... Green hologram, 23 ... Blue Hologram.

Claims (7)

[Claims] 1. Image light of red (R), green (G), blue (B)
A hologram having a function of spectrally diffracting light into R, G,
B is arranged at the image forming position of the image of each color, and R, G,
An image input / output device using a hologram, comprising: an image receiving section in which B light receiving pixels are arranged, and image light is spectrally diffracted by the hologram and input to the corresponding light receiving pixels for each pixel. 2. The apparatus according to claim 1, wherein the hologram is formed by superposing three transmissive holograms corresponding to respective wavelengths of R, G and B, or by triple recording in a photosensitive material of one layer. An image input / output device using a hologram, which is characterized by comprising a transmission hologram. 3. The apparatus according to claim 1, wherein the hologram is a transmission hologram that diffracts all R, G, and B wavelengths with one sheet and has no or little wavelength dependence of diffraction efficiency. An image input / output device using a hologram. 4. A hologram in which a plurality of holograms having wavelength dependence of diffraction efficiency are bonded together, or a hologram in which a plurality of holograms are multiplex-recorded in one layer and an image spectrally diffracted into each color of R, G, B by the hologram An image receiving unit in which light is incident and R, G, B light receiving pixels are arrayed periodically, and the image light is dispersed into each pixel by the hologram,
An image input / output device using a hologram, characterized in that the light is guided to each corresponding light receiving pixel and the remaining light is guided as a complementary color to the corresponding light receiving pixel directly below. 5. An image input / output device using a hologram according to any one of claims 1 to 4, wherein the hologram has a condensing property. 6. The apparatus according to any one of claims 1 to 4, wherein a condensing element is arranged at the image receiving side of the hologram or the image incident side at a period corresponding to the period. Image input / output device using hologram. 7. The apparatus according to claim 1, wherein the light of each color divided by the hologram is further restricted by the color filter corresponding to each light to enter the image receiving portion. An image input / output device using a hologram.