JPH0446323A - Optical deflector - Google Patents

Abstract

PURPOSE:To allow the total reflection or total transmission of incident light by admitting the incident light having the incident angle to a material between the critical angle when a voltage is impressed to the material and the critical angle when the voltage is not impressed to the material into the material, thereby changing the refractive index of the material. CONSTITUTION:The optical deflector 10 consists of 1st, 2nd prisms 12, 14 and a liquid crystal, etc., 16 and a rectangular prism made of glass or plastic is used for the prisms 12, 14. The liquid crystal 16 is sealed between the 1st and 2nd prisms 12 and 14 and the refractive index nA of the liquid crystal is 1.3 when the voltage is impressed and 1.4 when the voltage is not impressed. A power source, not shown in Fig., is electrically connected to the liquid crystal 16. The case of the impression of the voltage to the liquid crystal 16 and the case of the non-impression of the voltage thereto are selected by the operation of this power source. The relation between the refractive index and the critical angle is as follows: The critical angle increases with an increase in the refractive index and the liquid crystal 16 totally reflects the incident light when the incident angle is larger than the critical angle. The incident light transmits the liquid crystal 16 when the incident angle is smaller than the critical angle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical deflector, and particularly to an optical deflector used in a camera shutter or the like.

[Conventional technology]

Conventionally, an optical path converter or an optical shutter is used in a camera cover, and the optical path converter switches the optical path by driving a quick return mirror.

In addition, the optical shutter turns on the optical path by opening and closing the shutter.

There are focal brain shutters, lens shutters, electro-optical shutters, electronic shutters, and the like.

The focal brain shutter runs through a slit to obtain uniform exposure in each part of the screen, the lens shutter narrows down the screen and blocks the optical path, and the electro-optic shutter uses a polarizer and an analyzer to turn the optical path ON and OFF. In addition, the electronic shutter turns on and off the subject input using the CCD.

[Problem that the invention attempts to solve]

However, the optical path converter has a complicated mechanism, resulting in high cost, and has problems in durability and responsiveness. Further, since the focal brain shutter has a configuration in which a slit runs, the entire screen cannot be opened or closed, and there are also problems in that it is expensive and does not have sufficient durability.

Lens shutters have the problem of not being able to maintain uniform exposure of each part of the screen and poor accuracy, and electro-optic shutters have a problem of losing approximately half or more of the amount of light due to polarizers and the like. Further, electronic shutters have problems in that the shutter function circuit is expensive, and frame-type shutters have poor image quality.

The present invention was developed in view of these circumstances, and has advantages such as being highly reliable and accurate, being able to switch optical paths instantaneously, and preventing loss of light quantity and deterioration of image quality. The purpose is to provide an optical deflector.

[Means to solve problems]

In order to achieve the above object, the present invention is an optical deflector in which a material whose refractive index changes depending on a voltage is inserted between a first prism and a 9J2 prism facing each other, and the incident angle to the material is , incident light between the critical angle when a voltage is applied and the critical angle when no voltage is applied is made incident on the material, and the incident light is totally reflected or totally transmitted by changing the refractive index of the material. It is characterized by causing

[Effect]

According to the present invention, a material whose refractive index changes with the application of voltage is inserted between the first prism and the second prism, and the range of the critical angle of the inserted material that corresponds to the change in the refractive index of incident light. The first and second prisms were placed between the crotches so that they were incident on the insertion material within the groin. Therefore, when a voltage is applied to the insertion material to change the refractive index, the incident light can be totally reflected by the insertion material or transmitted through the insertion material due to the change in the refractive index, so it is only necessary to apply a voltage to the liquid crystal member. By adjusting the , the optical path can be guided to the imaging surface or switched from the imaging surface to a different direction.

〔Example〕

The optical deflector according to the present invention will be explained in detail below with reference to the accompanying drawings.

As shown in FIG. 1, the optical deflector 10 consists of first and second prisms 12.14 and a liquid crystal etc. 16.
14 is a right angle prism made of glass or plastic. Furthermore, the liquid crystal 16 is connected to the first and second prisms 1.
2.14, and the refractive index of this liquid crystal < n
A> becomes 1.3 when a voltage is applied, and becomes 1.4 when no voltage is applied. Further, a power source (not shown) is electrically connected to the liquid crystal 16, and by operating this power source, it is possible to switch between applying a voltage to the liquid crystal 16 and not applying a voltage.

When using this liquid crystal 16 as a nyatta, the liquid crystal 16
Each liquid crystal 1 with and without voltage applied to
The critical angles corresponding to the refractive index of 6 are determined, and the optical deflector 10 is set so that the incident light enters the liquid crystal 16 within the range of each determined critical angle.

Here, the relationship between the refractive index and the critical angle is that as the refractive index increases, the critical angle increases; when the incident angle is larger than the critical angle, the liquid crystal 16 totally reflects the incident light, and when the incident angle is smaller than the critical angle, the incident light is transmitted through the liquid crystal 16. Therefore, the refractive index is 1
．． When the refractive index is set to 3, the incident light is totally reflected by the liquid crystal 16, and when the refractive index is set to 1.4, the incident light is transmitted through the liquid crystal 16.

Therefore, the critical angle (i) when the refractive index (n, ) of the liquid crystal 16 is 1.3 and 1.4 is determined.

First, when the refractive index (n, ) is 1.3 and the refractive index of the prism 14 is set to nl, the following equation can be obtained.

Here, if a type of glass prism with a refractive index (n11) of 1.9176 is used as the first prism 12, the critical angle when voltage is applied is critical angle (i) = 42.6.
It becomes 82°.

Also, when the refractive index (nB) is 1.4, the critical angle (1) when no voltage is applied is the critical angle (i) - 4 from formula 0.
It becomes 6,893°.

Therefore, the liquid crystal surface 16A of the liquid crystal 16 has a angle of 42.682° to 4°.
When light is incident at an angle within the range of 6.893", the incident light is transmitted through the liquid crystal surface 16A when no voltage is applied to the liquid crystal 16, and when a voltage is applied to the liquid crystal 16, the incident light is transmitted through the liquid crystal surface 16A.
Total reflection occurs at 6. This allows the liquid crystal 16 to be used as a shutter.

FIG. 3 shows one embodiment of the optical deflector according to the present invention. The liquid crystal 16 of the optical deflector 10 is provided so as to maintain a predetermined inclination with respect to the optical axis of the lens. Then, the lenses 20 to 34 are arranged as shown in Fig. 3, and the focal length (
f) to 2500 mm (approximately 1° diagonally of view), aperture (F
) is set to 16, and the emitted light 36 from the lens is 42.6.
8° (when voltage is applied) to 46.89° (when no voltage is applied)
The light is made to enter the liquid crystal 16 at an incident angle of .

Therefore, when no voltage is applied to the liquid crystal 16, the incident light 3
6 passes through the liquid crystal 16 and travels straight. Further, when a voltage is applied to the liquid crystal 16, the incident light 36 is totally reflected by the liquid crystal 16, and the reflected light 36A forms an image on the imaging surface 40. As described above, according to the present invention, the optical path can be changed simply by applying a voltage to the liquid crystal 16.

In addition, an electro-optic effect material (PLZT) is used instead of the liquid crystal 16.
, L i NbO, etc.) also work in a similar manner.

Note that the optical deflector 10 may be provided anywhere within the range A in FIG.

〔Effect of the invention〕

As described above, according to the optical deflector according to the present invention, it is possible to change the refractive index of the liquid crystal by applying a voltage so that the incident light is totally reflected by the liquid crystal, or the incident light can be adjusted so that it is transmitted through the liquid crystal. . Therefore, unlike an electro-optical shutter, the amount of light does not decrease due to a polarizer or analyzer, and unlike an electronic shutter, the cost of the shutter circuit does not increase. Further, unlike a lens shutter, it is not possible to maintain uniform exposure, and unlike a focal brain shutter, there is no problem that the entire screen cannot be turned on and off.

Furthermore, unlike optical path converters, the mechanism does not become a pelvic fin.

As a result, reliability and accuracy can be improved, the optical path can be switched instantaneously, and light loss and image quality deterioration can be prevented, and costs can be reduced. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the optical deflector according to the present invention, FIG. 2 is a diagram showing the refraction state of incident light, and FIG. 3 is a side view showing an embodiment in which the optical deflector according to the present invention is used. It is. 10... Optical deflector, 12.14... Prism,
16...Liquid crystal.

Claims (1)

[Scope of Claims] An optical deflector in which a material whose refractive index changes depending on a voltage is inserted between a first prism and a second prism that face each other, the incident angle to the material being adjusted by the voltage applied to the material. The method is characterized in that incident light between a critical angle when a voltage is applied and a critical angle when no voltage is applied is made incident, and the incident light is totally reflected or totally transmitted by changing the refractive index of the material. optical deflector.