JP2012247842A - Image acquisition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image acquisition device in which respective imaging systems can be easily and optically adjusted.SOLUTION: A primary detector 2 has the same visual axis as the optical axis of a common optical system 1 and also has its focus adjusted to be in an optical arrangement eliminating the need for re-adjustment. A double wedge type scanner 4 is provided between a secondary detector 3 and an optical system 1. The double wedge type scanner 4 comprises two wedge prisms which have arbitrary one-side planes arranged in parallel, the first wedge prism and second wedge prism have a common or parallel axes of rotation, and at least one wedge prism is configured to move in parallel.

Description

  The present invention relates to an image acquisition apparatus that acquires images having different visual axes from a single imaging optical system.

  As one of the means to acquire images in a plurality of different wavelength ranges with a single imaging optical system, imaging is performed on different detectors using a dichroic mirror capable of wavelength separation of reflected light and transmitted light. A way to do it has been proposed. For example, in an optical system as shown in Non-Patent Document 1, a dichroic beam splitter is used to reflect the visible region and transmit the infrared region to separate the bands and acquire images in different wavelength regions. ing. This image acquisition device has four bands (3.5 to 4.0 μm, 6.5 to 7.0 μm, 10.3 to 11.3 μm, 11.5 to 12.5 μm) in the infrared region, Improvement of the SN ratio of each wavelength band is required in a wide wavelength range. However, there is a problem that it is difficult to select a base material that has a low light amount loss in a plurality of wavelength bands.

  As a means for solving this problem, a technique for acquiring images with different visual axes has been proposed. For example, in the optical system according to Patent Document 1, the common optical system forms an image on a first detector and a second detector that convert a light intensity image into an electrical signal, and protects the first package and the second package. And a window through which light rays pass through the package. Further, when the first detector is a group b and the second detector is a group c, an optical image can be formed on the group c by having a reflecting mirror in a window provided in the first package. Since the detectors b and c having different visual axes can acquire an image without having a dichroic mirror, it is possible to perform light loss reduction processing for each wavelength on each window. Therefore, it is possible to obtain a light intensity image with reduced light loss in a plurality of wavelength bands.

JP 2007-278724 A

J.J.Puschell, “Japanese Advanced Meteorological Imager (JAMI): Design, Characterization and Expected On-Orbit Performance”, Proc. Of the 13th Int. TOVS Study Conference, Sainte Adele, Canada, 2003 (617-633, fig.4)

  However, in order to reduce the light amount loss as described above, when images having different visual axes are acquired using a common optical system, the visual axes and the focal points are different from each image plane. At that time, there is a problem that it is difficult to perform optical adjustment of each imaging system at the same time in a common optical system. In addition, when coma occurs on the imaging plane whose visual axis is different from the optical axis of the optical system, there is a problem that imaging performance is degraded.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an image acquisition apparatus capable of easily performing optical adjustment of each imaging system.

  An image acquisition device according to the present invention includes an optical system for forming an optical image of a subject, a first conversion device that converts light intensity of an optical image formed by light from the optical system into an electrical signal, A second conversion device that converts the light intensity of an optical image formed on an optical path different from the optical path from the optical system to the first conversion device into an electrical signal, and two sheets each having an arbitrary surface arranged in parallel A first wedge prism and a second wedge prism having a common or parallel rotation axis, and at least one of the wedge prisms includes a double wedge type scanner capable of translation, A double wedge type scanner is provided between at least one of the conversion device or the second conversion device and the optical system.

  In the image acquisition device according to the present invention, since the double wedge type scanner is provided between at least one of the first conversion device and the second conversion device and the optical system, optical adjustment of each imaging system is easy. Can be done.

It is a block diagram which shows the image acquisition apparatus by Embodiment 1 of this invention. It is explanatory drawing of the double wedge type scanner of the image acquisition apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the change of the visual axis with respect to one wedge prism of the image acquisition apparatus by Embodiment 1 of this invention. It is a block diagram which shows the image acquisition apparatus by Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing an image acquisition apparatus according to Embodiment 1 of the present invention.
The image acquisition apparatus shown in FIG. 1 includes an optical system 1, a primary detector (first conversion device) 2, a secondary detector (second conversion device) 3, and a double wedge scanner 4. The optical system 1 is an optical system common to these detectors that form an image on the primary detector 2 and the secondary detector 3. The primary detector 2 has an optical arrangement in which the optical axis and the visual axis of the common optical system 1 are equal, focus adjustment is performed, and readjustment is unnecessary. On the other hand, the secondary detector 3 has a visual axis different from the optical axis of the common optical system 1 and is arranged so as to be able to form an image independent of the primary detector 2. The double wedge scanner 4 is an independent optical adjustment mechanism that is inserted between the common optical system 1 and the secondary detector 3 in order to perform optical adjustment of the secondary detector 3.

FIG. 2 is an explanatory diagram of the double wedge type scanner 4.
The double wedge type scanner 4 is composed of two wedge prisms, a wedge prism 5 and a wedge prism 6. When the opposing surfaces of the wedge prism 5 and the wedge prism 6 are surfaces 5a and 6a, the surfaces 5a and 6a are parallel to each other. Deploy. Further, the point where the prism thickness is minimized and the point where the prism thickness is maximized are connected on the surface 5a, and the vector line 5b is set in the direction in which the prism thickness increases starting from the smallest point. Similarly, a vector line 6 b is set for the wedge prism 6. In addition, an axis A perpendicular to these surfaces 5a and 6a is set. The wedge prisms 5 and 6 are rotatable about the axis A, and the wedge prism 5 is configured to be slidable in the direction of the vector line 5b.

  In the configuration example shown in FIG. 1, all adjustments necessary for visual axis correction can be performed by using the double wedge type scanner 4. That is, by sliding the wedge prism 5 parallel to the direction of the vector line 5b, the optical path length passing through the double wedge structure can be changed, so that focusing can be performed. Further, by rotating the wedge prism 5 and the wedge prism 6 about the axis A, it is possible to correct the axis deviation.

Next, axis deviation correction will be described. For simplicity of explanation, the wedge prism thickness and the gap between the two wedge prisms are ignored.
FIG. 3 shows changes in the visual axis for one wedge prism. A plane perpendicular to the axis A is defined as an xy plane, and a point where the x component of the vector line 5b is maximum is defined as a rotation angle α = 0 of the wedge prism 5. The x component θ _x5 of the deflection angle when α = 0 is maximized, and this angle is δ. As is apparent from FIG. 3, θ _x5 is displaced from −δ ₅ (α = π) to + δ ₅ (α = 0). Further, the rotation angle β is similarly set for the wedge prism 6, and the point where the x component of the vector line 6b is maximized is set to the wedge prism rotation angle β = 0. The deflection angle of the light beam that has passed through the two wedge prisms can be expressed by Equations 1 and 2.
θ _x = δ ₅ cos α + δ ₆ cos β (Expression 1)
θ _y = δ ₅ sin α + δ ₆ sin β (Expression 2)
Accordingly, from these two equations, the deflection angles θ _x and θ _y are
θ _x ² + θ _y ² ≦ (δ ₅ + δ ₆ ) ²
Can be arbitrarily determined from α and β.

  The double wedge type scanner 4 may be configured so that the visual axis is incident obliquely. In other words, the incident visual axis and the axis A are not matched. In an optical system in which the visual axis is not on the optical axis, coma aberration or the like may occur. Imaging performance can be improved by canceling out this coma aberration and the eccentric coma aberration generated by oblique incidence on the double wedge scanner 4.

  When the double wedge type scanner 4 is not equivalent to a parallel plate, that is, when the vector line 5b of the wedge prism 5 and the vector line 6b of the wedge prism 6 do not completely overlap, the visual axis correction origin is set. Also good. If the visual axis correction is performed in a state where the double wedge type scanner is close to a parallel plate, the amount of rotation of the scanner becomes large and is likely to become unstable (see, for example, JP-A-2009-236580). Therefore, highly stable adjustment can be performed by setting the correction origin to a state in which the vector line 5b and the vector line 6b do not completely overlap.

  Further, by using germanium, silicon, zinc sulfide (ZnS), zinc selenide (ZnSe), or chalcogenide glass which is a high refractive index material as the material of the double wedge type scanner 4, the change in the refraction angle and the optical path length is achieved. Therefore, a thin scanner can be obtained.

  As described above, according to the image acquisition apparatus of the first embodiment, an optical system for forming an optical image of a subject and the light intensity of the optical image formed by the light beam from the optical system are converted into electrical signals. A first conversion device for conversion, a second conversion device for converting the light intensity of an optical image formed on an optical path different from the optical path from the optical system to the first conversion device, into an electrical signal, and each arbitrary The first wedge prism and the second wedge prism have a common or parallel rotation axis, and at least one of the wedge prisms is a double that can move in parallel. A wedge type scanner is provided, and a double wedge type scanner is provided between at least one of the first conversion device or the second conversion device and the optical system, so that optical adjustment of each imaging system is easy. It can be carried out.

  In addition, according to the image acquisition apparatus of the first embodiment, the double wedge type scanner uses the asymmetrical arrangement with respect to the opposing surfaces of the two wedge prisms as the correction origin, so that highly stable adjustment can be performed. it can.

Embodiment 2. FIG.
FIG. 4 shows an image acquisition apparatus according to Embodiment 2 for carrying out the present invention. The portions corresponding to those in FIG. 1 in the first embodiment are given the same numbers, and description thereof is omitted. The image acquisition device according to the second embodiment is obtained by arranging a relay lens 7 for re-imaging the secondary detector 3 in the image acquisition device according to the first embodiment. The rest is the same as FIG.

When the detection wavelengths of the primary detector 2 and the secondary detector 3 are different, the image size may be different due to lateral chromatic aberration. In such a case, the image formed in the optical system 1 is re-imaged by using the relay lens 7 so that the image is enlarged or reduced to be equal to the ratio of the primary detector 2 and the secondary detector 3. It is possible to obtain a light intensity image having an arbitrary resolution in different wavelength bands.
Further, when the relay lens 7 is used, the position of the secondary detector 3 in the visual axis direction can be arbitrarily set by re-imaging the intermediate image of the common optical system 1.

  As described above, according to the image acquisition device of the second embodiment, the first conversion device or the first conversion device or at least one of the first conversion device and the second conversion device is provided between the double wedge scanner and the first conversion device or the second conversion device. Since the relay lens for re-imaging by the second converter is provided, a light intensity image having an arbitrary resolution in different wavelength bands can be obtained, and the converter on the side provided with the double wedge scanner The position with respect to the visual axis direction can be arbitrarily set.

  In the present invention, within the scope of the invention, the embodiments can be freely combined, any component of each embodiment can be modified, or any component can be omitted in each embodiment. .

  DESCRIPTION OF SYMBOLS 1 Optical system, 2 Primary detector (1st converter), 3 Secondary detector (2nd converter), 4 Double wedge type scanner, 5,6 Wedge prism, 5a, 6a surface, 5b, 6b Vector line 7 Relay lens.

Claims (3)

An optical system for forming an optical image of a subject;
A first conversion device that converts light intensity of an optical image formed by a light beam from the optical system into an electrical signal;
A second converter that converts light intensity of an optical image formed on an optical path different from an optical path from the optical system to the first converter, into an electrical signal;
Each wedge is composed of two wedge prisms arranged in parallel, the first wedge prism and the second wedge prism have a common or parallel rotation axis, and at least one of the wedge prisms is translated. With a double wedge type scanner,
An image acquisition apparatus, wherein the double wedge type scanner is provided between at least one of the first conversion apparatus and the second conversion apparatus and the optical system.   2. The image acquisition apparatus according to claim 1, wherein the double wedge type scanner uses a correction origin as an asymmetrical arrangement with respect to opposing surfaces of two wedge prisms.   A relay lens for re-imaging by the first conversion device or the second conversion device is provided between the double wedge type scanner and at least one of the first conversion device and the second conversion device. The image acquisition apparatus according to claim 1, wherein the image acquisition apparatus is an image acquisition apparatus.

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