JPH03107931A - Oscillation isolator for image pickup optical system - Google Patents

Abstract

PURPOSE:To correct the fluctuation of an image position due to hand shaking, etc., even with a simple mechanism by arranging a refractive index variable optical device having an inclined plane against at least one optical axis in an image pickup optical system, and varying the refractive index of the refractive index variable optical device electrically corresponding to the oscillation of the image pickup optical system. CONSTITUTION:The refractive index variable optical device 3 comprised by combining a wedge liquid crystal prism 1 having equal apex angles with a wedge prism 2 consisting of glass with constant refractive index in upside down with each other is arranged in the image pickup optical device. The refractive index of the wedge liquid crystal prism 1 can be varied by turning on or off an impression voltage by a power source E or varying the magnitude of the impression voltage. And it is possible to bend an optical path by varying the refractive index of liquid crystal corresponding to the displacement of the optical system, and to control the deflection angle of it. Thereby, the fluctuation of the image position due to the hand shaking, etc., can be corrected even with the simple mechanism.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an image stabilizing device for an imaging optical system such as a camera.

[Conventional technology]

BACKGROUND ART In imaging optical systems such as cameras, especially telephoto lenses, deterioration of image quality due to vibrations such as camera shake is a major problem. Currently, various vibration isolating devices are being considered. For example, as described in JP-A-62-153816, an easily deformable transparent material is enclosed between two transparent plates to prevent vibrations such as camera shake. Some use a variable apex prism, etc., which bends the optical path by tilting two transparent plates depending on the situation, thereby preventing fluctuations in the image position.

[Problem to be solved by the invention]

However, the above-mentioned conventional example requires a mechanical drive device, which has the disadvantage that the mechanism is complicated.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an image stabilizing device for an imaging optical system, which has a simple mechanism and is capable of correcting fluctuations in image position due to camera shake and the like.

[Means and effects for solving the problems] A vibration isolating device for an imaging optical system according to the present invention includes a variable refractive index optical element having at least one surface tilted with respect to the optical axis arranged in the imaging optical system, By electrically changing the refractive index of the variable refractive index optical element in accordance with the vibrations of the imaging optical system to correct fluctuations in the image position caused by the vibrations, the mechanical drive device can be corrected. This makes it possible to perform correction without using it.

That is, the image stabilization device according to the present invention bends the optical path by arranging a variable refractive index optical element consisting of one or more wedge-shaped prisms or obliquely tilted parallel flat plates in the imaging optical system, thereby preventing vibration caused by camera shake or the like. It is designed to compensate for fluctuations in image position. As shown in FIG. 1(A), the wedge-shaped prism gives an angle of deviation θ to the emitted ray with respect to the incident ray, and this angle of deviation θ changes depending on the apex angle α and the refractive index n of the prism.

Furthermore, as shown in Figure 1(B), a ray of light that is horizontally incident on an obliquely inclined parallel plate is displaced by δ and exits horizontally, but this displacement δ is equal to the thickness t of the parallel plate. and changes depending on the refractive index n. In the image stabilization device according to the present invention, the deflection angle θ or displacement δ of the optical path is controlled by changing the refractive index n of the wedge prism or parallel plate according to the displacement of the optical system, thereby preventing fluctuations in the image position due to camera shake. It is supposed to be done.

[Example] Hereinafter, the present invention will be described in detail based on the illustrated example.

FIG. 2 shows the main part of the first embodiment, which includes a wedge-shaped liquid crystal prism l with an equal apex angle in an imaging optical system (not shown).
A variable refractive index optical element 3 is disposed in which a wedge-shaped prism 2 made of glass with a constant refractive index is combined upside down. The wedge-shaped liquid crystal prism 1 is formed by sealing a liquid crystal inside a wedge-shaped cell, and the refractive index can be changed by turning on/off the applied voltage by the power source E or by changing the magnitude of the applied voltage. It is possible.

Since this embodiment is configured as described above, if the refractive index of the liquid crystal is made equal to the refractive index of glass in a state where the optical system is not displaced, the variable refractive index optical element 3 becomes a parallel flat glass, and the optical path However, by changing the refractive index of the liquid crystal according to the displacement of the optical system, the optical path can be bent as shown in FIG. 2, and the angle of deviation can be controlled. Therefore, even if the image position fluctuates due to the displacement of the optical system caused by vibration, the fluctuation can be immediately corrected.

In this way, deterioration in image quality due to vibrations such as camera shake can be prevented, but since this embodiment can perform correction without using a mechanical drive device, the mechanism is extremely simple.

FIG. 3 shows the main part of the second embodiment, which has a variable refractive index optical element 3 formed by combining a plurality of wedge-shaped liquid crystal prisms 11 to 16 and a wedge-shaped prism 2 made of glass. . Therefore, each wedge-shaped liquid crystal prism 11-1. By changing the refractive index of each independently, the polarization angle of the optical path can be controlled more precisely.

FIG. 4 shows the main part of the third embodiment, in which a liquid crystal parallel plate 4 is replaced by a wedge-shaped prism 2 made of two glass sheets with equal apex angles and opposite sides. ．． 2. A variable refractive index optical element 3 is provided obliquely between the two. Therefore, in a state where there is no displacement of the optical system, if the refractive index of the liquid crystal is made equal to the refractive index of the glass, the displacement of the optical path is 0, but if the refractive index of the liquid crystal is changed according to the displacement of the optical system, then the displacement of the optical path is 0. , the optical path can be displaced, and the amount of displacement can be controlled.

FIG. 5 shows the main part of the fourth embodiment, which consists of two wedge-shaped prisms 2 and 3 of the third embodiment. ．． 2. Between them, a plurality of liquid crystal parallel flat plates 41 to 4. It has a variable refractive index optical element 3 formed by sandwiching a variable refractive index optical element 3. Therefore, each liquid crystal parallel plate 41 to 4
．． By changing the refractive index of each independently, the amount of displacement of the optical path can be controlled more precisely.

In each of the above embodiments, by rotating the variable refractive index optical element 3 around the optical axis, it is possible to bend or displace the optical path in any direction symmetrically with respect to the optical axis, but the same wedge-shaped liquid crystal prism Alternatively, if you stack several liquid crystal parallel plates in different directions, you can use them without having to move them mechanically (
, it is possible to bend or displace the optical path in all directions.

FIG. 6 shows a main part of a fifth embodiment, which is an example thereof, and FIGS. 6(A) and 6(B) are a side view and a plan view thereof, respectively. This consists of four identical wedge-shaped liquid crystal prisms 1. ~1
．． are arranged opposite to each other (1', Ib, lc and 1.) and at right angles (1,,
It has a variable refractive index optical element 3 which is superimposed on the optical fibers lb and ICjl.

Since this embodiment is constructed as described above, the wedge-shaped liquid crystal prism 1. ．． When the refractive index of the wedge-shaped liquid crystal prisms 1e is made larger than that of glass and the refractive index of the wedge-shaped liquid crystal prisms lb and la is made equal to that of glass, the optical path is bent as shown by the solid line, and the wedge-shaped liquid crystal prisms 1. ．． If we make the refractive index of 1c equal to that of glass and the refractive index of wedge-shaped liquid crystal prisms lb and la larger than that of glass, the optical path will be bent as shown by the dotted line.Thus, the optical path will be bent in all directions without mechanical movement. Is possible.

Although not shown in the drawings, if a plurality of parallel liquid crystal plates are used instead of the same plurality of wedge-shaped liquid crystal prisms to create a combination similar to that of the fifth embodiment, the optical path can be spread in all directions without mechanical movement. It is possible to displace the

FIG. 7 shows the overall configuration of the fifth embodiment, in which 5 is a photographing lens, 9 is an image plane, and the variable refractive index optical element 3 shown in FIG. 6 is arranged between them. There is. and,
Each of the wedge-shaped liquid crystal prisms 11 to 1 of the variable refractive index optical element 3,
are the power supplies for voltage application 6. - 64, and these power supplies 61-64 are controlled by a control circuit 8 in response to a vibration detection signal from a vibration detection sensor 7. Therefore, the four wedge-shaped liquid crystal prisms 1. ~14
voltage is applied to prevent image quality from deteriorating due to vibration.

Note that the first to fourth embodiments can also be configured as shown in FIG. 7, and if the image is shifted by δ on the image plane 9 due to vibrations such as camera shake, Now, assuming that the distance from the final surface of the variable refractive index optical element 3 to the image plane 9 is X, the refractive index of the liquid crystal is adjusted so that the optical path is bent by an angle ε such that Xε=δ in the direction that corrects the deviation of the exit angle. In the third and fourth embodiments, it is sufficient to change the refractive index of the liquid crystal so as to displace the optical path by δ in the direction of correcting the deviation.

〔Effect of the invention〕

As described above, the image stabilizing device for an imaging optical system according to the present invention has a simple mechanism and has the important practical advantage of being able to correct fluctuations in image position due to camera shake and the like.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing the basic principle of a variable refractive index optical element of a vibration isolator for an imaging optical system according to the present invention, and FIGS. 2 to 5 are diagrams showing main parts of the first to fourth embodiments, respectively. , Figure 6 (A
) and (B) are a side view and a plan view of essential parts of the fifth embodiment, respectively, and FIG. 7 is a diagram showing the overall configuration of the fifth embodiment. 1.1. ~1. ．． t, ~1. ...Wedge-shaped liquid crystal prism, 2,2. ．． 22... Wedge-shaped prism, 3... Variable refractive index optical element, 4, 41-4. ...Liquid crystal parallel plate, 4a-4o...Parallel plate, 5...Photographing lens, 61-6. ...Power source, 7...Vibration detection sensor, 8...Control circuit, 9...Image plane. Figure 1 Figure 2 Figure 6 Q b C Figure 4 Figure 1 Figure 5 Figure 7

Claims (1)

[Claims] A variable refractive index optical element having at least one surface tilted with respect to an optical axis is disposed in an imaging optical system, and the refractive index of the variable refractive index optical element is electrically changed according to vibrations of the imaging optical system. A vibration isolating device for an imaging optical system, which corrects fluctuations in image position caused by the vibration.