JPH01207715A - Three-color decomposing optical system - Google Patents

Abstract

PURPOSE:To arrange respective optical images obtained by decomposition adjacently on one and the same plane by utilizing the extension of optical length based upon a prism. CONSTITUTION:A double refraction prism P1 having a crystal axis 2 separates light made incident from an image pickup lens L through a 1/4 wavelength plate S1 into two refracted beams consisting of a normal beam R1 and an abnor mal beam R2. A double refraction prism P2 having a crystal axis 2 separates the normal beam R1 made incident through a 1/4 wavelength plate S2 into two refracted beams consisting of a normal beam R3 and an abnormal beam R4. On the other hand, an optical length correcting prism is disposed in the optical path of the abnormal beams R2 in order to extending the optical length of the abnormal beam R2. Namely, respective crystal faces can be adjacently arranged on a straight line of the same plane by extending the optical lengths of the abnormal beam R2 and the normal beam R3 respectively by the prisms P3, P4 by respective prescribed distances.

Description

[Detailed description of the invention] (Industrial application field) The present invention is giyIIi! The present invention relates to a three-color separation optical system used in a color image capture device having image resolution and various other color decoy image devices.

(Conventional technique vi4) The video signal obtained by capturing the optical image of the subject using a color imaging device is easy to edit, 1-rimming, and other image signal processing, and is reversible so that the green signal can be erased. The color one-image device, which has been commonly used to generate video signals, is characterized by the ease of recording and reproducing using a recording member with
The optical image of the object passed through the image lens is formed on the photoelectric conversion section of the '#1 image element' via the color separation optical system, and the photoelectric conversion section of the image sensor generates an electrical image corresponding to the optical image of the object. It has a configuration that can convert the electrical image information into information and output the electrical image information as a serial video signal on the time axis. Various lI image tubes and various solid a
It is well known that m elements are used.

Furthermore, when recording a color image by capturing an optical image of a subject, a multilayer color film is most commonly used.

As is well known, in recent years, as the demand for high-quality and high-resolution playback images has increased, new television systems such as so-called EDTV and HDTV have been proposed. It is.

By the way, in order to obtain a high-quality, high-resolution 81-degree reproduced image, a color carrier device that can generate a video signal capable of reproducing a high-quality, high-resolution reproduced image is required. However, in color imaging (II) devices that use an image pickup tube as an image sensor, there is a limit to miniaturizing the electron beam diameter in the image pickup tube, so it is possible to achieve a high wIa of 1 degree by miniaturizing the electron beam diameter. However, since the target capacity of the image pickup tube increases in proportion to the target area, it is not possible to achieve higher resolution by increasing the target area. In this case, as the resolution increases, the frequency band of the video signal increases from several -1 MHz to several hundred MHz or more, which poses a problem in terms of S/N. It is difficult to generate a video signal that allows a device to reproduce a high-quality, high-resolution reproduced image.

The above point will be specifically explained as follows. In other words, color 1 uses an image pickup tube as an image carrier.
In order to generate video signals that can reproduce high-quality, high-resolution images using an imaging device, it is necessary to miniaturize the electron beam diameter in the imaging tube or use a large-area target. is possible.

However, there is a limit to miniaturizing the electron beam diameter of the imaging tube due to the performance of the electron gun in the imaging tube and the structure of the focusing system, so there is a limit to increasing resolution by miniaturizing the electron beam diameter. When trying to obtain high resolution by increasing the area of the target while using an imaging lens with a large captured image size, the increase in target capacity causes a drop in high-frequency signal components in the output signal of the image pickup tube. As the S/N of the image pickup tube output signal becomes significantly lower, some color image carriers using III picture tubes can generate video signals that can reproduce high-quality, high-resolution images. It is not possible to do so.

In addition, in order to reproduce high-quality, high-resolution images using a color imaging device that uses a solid-state image sensor as an image sensor, it is necessary to use a solid-state image sensor with a large number of pixels. The frequency of the clock for driving a large number of solid-state image elements becomes high (for example, in the case of a video camera, the frequency of the clock for driving a solid-state image sensor is several hundred M I]Z). At the same time, the capacitance value of the circuit being driven is increasing due to the increase in the number of pixels.
Considering the current state of MHz, it is considered that it cannot be constructed as a practical device.

As described above, due to the presence of an image sensor that is essential to the configuration of the conventional color image carrier, it is difficult to generate a video signal that can reproduce a reproduced image with high image quality and high M resolution. Since this could not be achieved, an improvement measure was required, so the applicant company first converted the optical image of the subject through the image carrier lens into two or more optical images having at least different wavelength ranges. means for resolving the two or more optical images into individual regions of one light-to-light conversion element; and means for forming an image on the light-to-light conversion element. means for re-projecting the optical image of the subject and the corresponding optical image information onto a reversible recording member using light, and recording optical information signals corresponding to a plurality of times on the reversible recording member. We have proposed a color imaging device with
A patent application has already been filed for No. 10768 "Color@Image Device".

And the color already proposed by the above-mentioned applicant company @
In an imaging device, a video signal capable of obtaining a high-resolution reproduced image can be easily obtained from a reversible recording member on which optical image information is recorded. According to this method, the problems of the conventional method can be solved satisfactorily.

(Problems to be Solved by the Invention) By the way, in configuring the previously proposed color imaging device described above, an optical image of a subject through an imaging lens is decomposed into at least two optical images having different wavelength ranges. It is necessary to form each of the optical images obtained in this manner onto a respective individual area of one light-to-light conversion element.

However, for example, the conventional color @
Like a three-color separation optical system used in an imaging device, each image-forming plane (lr I
n tb + and I(1+) were in a state of being spatially isolated from each other (in Fig. 3, 0 is the object, [ is the image carrier lens, Dr, Db is the dichroic mirror, Mr.

Mb+ is the image forming surface of the optical image of the red component, Ib+ is the image forming surface of the optical image of the blue component, 11J+
is the imaging plane of the optical image of the green component), it is necessary to use a special configuration as the light-to-light conversion element on which the plurality of optical images are to be formed, and therefore the equipment is difficult to use. This will cause problems in the configuration.

The spatial deviation of the C imaging plane 1r +, 'lb In 10 + is caused by the horizontal shift of the optical axis of each color component,
As shown in FIG. 3, the spatial deviation of the imaging plane coincides with the lateral deviation fia of the optical axis.

Further, as described above, the optical image of the subject passed through the imaging lens is separated into at least two optical images having different wavelength ranges, and each optical image obtained is recorded on a reversible recording member. Even when this is done, the individual imaging planes of each of the plurality of optical images obtained by color separation as described above are, for example, spatially separated, or the imaging planes are If the directions of the optical images of the imaged object are different, a plurality of reversible recording members will be required to record the plurality of optical images, and the configuration of the device will be different. The problem is complexity.

For example, when recording a color image using an irreversible recording member, it is possible to avoid the use of a multilayer color film, which poses a problem of fading, and to record the subject through an image carrier lens. The same problem as described above occurs when an optical image is separated into at least two optical images having different wavelength ranges and each optical image is recorded on a monochrome film.

Therefore, as a color separation optical system, each optical image obtained by separating the optical image of the subject through the imaging lens into at least two or more optical images having different wavelength ranges as described above,
They can be arranged in such a way that they are placed close to each other in the same plane, and the configuration is very convenient! The appearance of a simple color separation optical system is long awaited.

(Means for Solving the Problems) Therefore, in order to solve the above problems, the present invention separates into three colors using an optical system composed of two birefringent prisms with different crystal axis directions. This is a three-color separation optical system configured to obtain three optical images, and one of the two refracted lights separated by the first birefringent prism is refracted to extend the optical path length. a first imaging surface on which a first optical image is formed by light that passes through a third prism and enters a first color filter; and The other refracted light separated by the birefringent prism is made incident on the second birefringent prism via the 174-wave plate, and the two refracted lights separated by the second birefringent prism are
One of the two refracted lights passes through a fourth prism for extending the optical path length and enters a second color filter, and a second color filter is generated by the light transmitted through the second color filter.
A second imaging plane on which an optical image is formed, and the other refracted light separated by the second birefringent prism is made incident on a third color filter, and transmitted through the third color filter. A third optical image is formed by the light.
The object of the present invention is to provide a three-color separation optical system characterized in that the imaging planes of the image forming apparatus 1 and 2 are arranged close to each other in a straight line within the same plane.

(Example) A three-color separation optical system according to the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a diagram showing a schematic configuration of an embodiment of the three-color separation optical system according to the present invention, and FIG.
It is a figure showing the direction of the crystal axis of a wavelength plate.

In FIG. 1, L is an imaging lens and Sl.

S2 has crystal axes in the six directions of the arrows shown in Fig. 2 174
Wave plate (1/4 of the wavelength of the incident light on the imaging lens L)
It is.

Pl is a birefringent prism whose crystal axis 1 is fj, and the light incident from the image carrier lens L via the 174-wavelength plate S1 is
It is separated into two refracted lights: an ordinary ray R1 and an extraordinary ray R2. F2 is a birefringent prism with crystal axis 2, 17
The ordinary ray R1 is transmitted through the four-wavelength plate S2, and the ordinary ray R3 is
and the extraordinary ray R4.

F3 is the extraordinary ray 1 in order to extend the optical path length of the extraordinary ray R2.
! ; This is an optical path length correction prism provided in the optical path of lR2. Further, F4 is an optical path length correction prism provided in the optical path of the ordinary light 111R3 in order to extend the optical path length of the ordinary light mR3.

Furthermore, Fl, F2. F3 is each ray R2, R3
, R4, and the color filter F1 transmits only red light, the color filter F2 transmits only green light, and the color filter F3 transmits only blue light.

Here, the 174 wavelength plate S1 is a birefringent prism P
Even if the light incident on 1 has polarization characteristics, the ordinary IR
+ and extraordinary light [lR2 plays the role of keeping the ratio of the amount of light from changing (the role of a so-called debtorizer).

Furthermore, the 174-wavelength plate S2 makes the light incident on the birefringent prism P2 circularly polarized, thereby making the ratio of the light amounts of the ordinary ray R3 and the extraordinary ray R4 constant.

Note that the 174-wavelength plate S1 is inserted as necessary.

(r is the red color of object 0 in the light that passes through the optical path of object 0 → dynamic lens L → quarter-wave plate S1 → birefringent prism P1 → prism P3 → color filter F1). This is the imaging plane of the optical image by the component.Next, 1g
is the object O in the light that passes through the optical path of the object o-) photographing lens L → quarter-wave plate S1 → birefringent prism P1 → quarter-wave plate S2 → birefringent prism P2 → prism P4 → color filter F2. This is the imaging plane of the optical image based on the green component.

Furthermore, Ib is the value of object 0 in the light passing through the optical path of object 0 → Isho lens L → 1/4 wavelength plate S1 → birefringent prism P1 → 1/4 wavelength plate S2 → birefringent prism P2 → color filter F3. This is the imaging plane of the optical image based on the blue component.

In the three-color separation optical system of this embodiment, the optical path length of the extraordinary ray R2 is determined by the prism P3, and the optical path length of the ordinary ray tilR is determined by the prism P4.
: By extending the optical path lengths of + by predetermined lengths, the optical image of the subject formed on the above-mentioned image forming surface 1'' and the optical image of the subject formed on the above-mentioned image forming surface 1a can be changed to The images can be formed in a state in which they are arranged close to each other in a straight line within the same plane as the image forming surface 1b.

Further, each of the three optical images can be formed at the same magnification and in the same direction on each image forming plane.

In addition, in this embodiment, since the two refracted lights by the birefringent prism are emitted in the same direction, the conventional design rJ
There is no need for 4 mirrors, and it can be made more compact.

Note that the combination of the three color filters is not limited to this embodiment, and for example, the color filter F1 may only emit blue light, the color filter F2 may emit only red light, and the color filter E3 may emit only green light. may be made to be transparent. Also,
The ordinary light FJR+ of the birefringent prism P1 is transferred to the prism P3,
The extraordinary rays R2 may be directed to the birefringent prism P2.

Next, a method of using the three-color separation optical system of this embodiment will be explained.

First, by installing a photoelectric conversion element at the position tNE of the image forming plane shown in FIG. 1, a color decoy image device such as a video camera can be constructed.

In addition, a color image can be printed by placing a positive photographic paper at the position E of the image forming surface, and when printing an optical image from a negative color film, a three-color separation optical system is used. If you place negative photographic paper in position E, you can print a color image of Chito (however, if you look at it as is, it will be an inverted image of Terumaro).

Furthermore, a monochrome film is installed at position E of the image plane, avoiding the use of multilayer color films that are prone to fading, and records three optical images separated into three colors of subject 0. You may also do so. In order to reproduce images recorded on this chrome film as color images, it is necessary to irradiate each recorded image with light of the required color.

Note that even if the subject 0 is colorless, the three-color separation optical system of the present invention forms three optical images at the same magnification and in the same orientation on each imaging plane. be able to.

(Effects of the Invention) As described above, in the three-color separation optical system according to the present invention, each optical image obtained by separating an optical image of a subject through an image carrier lens into at least two or more optical images, Utilizing the extension of the optical path length by the prism, it is possible to arrange the plurality of optical images in a straight line in close proximity within the same plane, and moreover, the plurality of optical images described above can be arranged at the same magnification and in the same direction on each imaging plane. It is possible to construct a simple and compact three-color separation optical system that can form an image on a single monochrome film, as well as the optical system of the already proposed color eye imaging device mentioned above. This makes it possible to satisfactorily solve the above-mentioned problems in optical systems used to record images and prevent color fading.

4. f in the drawing! ! 1 is a diagram showing a schematic configuration of an embodiment of the three-color separation optical system according to the present invention, FIG. 2 is a diagram showing the direction of the crystal axis of the quarter-wave plate, and FIG. 1 is a diagram showing a schematic configuration of a three-color separation optical system used in a conventional color imaging device.

1.2...Crystal axis, F1-F3...Color filter, L
...cocoon-shaped lens, Pl, P2...birefringent prism,
P3. Pa... Prism for optical path length correction, Sl, S2.
...1/4 wavelength plate.

bone 2 mouth

Claims (1)

[Scope of Claims] A three-color separation optical system configured to obtain three optical images separated into three colors by an optical system including two birefringent prisms with mutually different crystal axis directions, Then, one of the two refracted lights separated by the first birefringent prism passes through a third prism for extending the optical path length and enters the first color filter. A first imaging plane on which a first optical image is formed by the light transmitted through the first color filter, and the other refracted light separated by the first birefringent prism are separated by a quarter wavelength plate. the two birefringent prisms separated by the second birefringent prism.
One of the two refracted lights passes through a fourth prism for extending the optical path length and enters a second color filter, and a second color filter is generated by the light transmitted through the second color filter.
A second imaging plane on which an optical image is formed, and the other refracted light separated by the second birefringent prism is made incident on a third color filter, and transmitted through the third color filter. A third optical image is formed by the light.
A three-color separation optical system characterized in that the imaging planes are arranged in a straight line and close to each other within the same plane.