JPS595201A - Beam splitter - Google Patents

Abstract

PURPOSE:To make a titled beam splitter easy to assemble and to adjust by providing the total reflection film in parallel flat plate glass in the position apart from the optical axis of a photographing lens. CONSTITUTION:A titled beam splitter is formed of a total reflection film 21 provided in parallel flat plate glass 20 consisting of inexpensive optical glass having excellent workability and small specific gravity. The greater part of the light transmitted through a photographing lens passes by the film 21 without shining on the same and the remaining light is formed an image by the photographing lens. On the other hand, the light shining on the film 21 is fully reflected and is made incident to an optical fiber system; therefore, the area of the film 21 is as small as about the same as in the prior art. Since the film 21 is provided apart from the optical axis 22 of the photographing lens, all the luminous fluxes having good quality in terms of aberration performance near the optical axis 22 are usable for photographing; therefore, even if the luminous fluxes are stopped small by an iris stop, the image forming performance of the photographing lens is kept free from deterioration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a beam splitter used in cameras and the like, which guides light transmitted through a photographic lens system to an optical finder.

Conventionally, a total reflection mirror 11 as shown in FIG. 1 has been used as a small and lightweight beam splinter of this type. Here, FIG. 1 (~ is a plan view of a conventional beam splitter, (B) is a front view, and (q is a side view.
- The optical axis of the photographing lens, the straight line 13 is a ray parallel to the optical axis 12 and hits the center of the total reflection mirror 11, and the straight line 14 is a ray 13
is the light beam bent by the total reflection mirror 11, and is the optical axis of the optical finder system. Although the conventional example shown in FIG. 1 provides a small and lightweight beam splitter, it has the disadvantage that assembly and adjustment are extremely difficult.

The present invention solves this problem and provides a beam splitter that is small, lightweight, and easy to assemble and adjust. That is, the present invention uses parallel flat glass with a total reflection film provided inside, so that assembly and adjustment are easy.
This realizes a small and lightweight beam splitter.

Next, one embodiment of the present invention will be described based on the drawings. FIG. 2 shows the configuration of an embodiment of the present invention.

Figure 2 (3) is a plan view of this embodiment, CB) is a front view, (CB) is a front view, (
q is a side view. In this embodiment, a total reflection film 21 is provided inside a flat glass 2o made of optical glass such as BK7 or SKs, which is inexpensive, has excellent workability, and has a small specific gravity. In Figure 2, straight line 2
2 is the optical axis of the photographing lens, a straight line 23 is a ray of light that passes through the center of the total reflection film and is parallel to the optical axis 22, and a straight line 24 is the ray of light 23 reflected by the total reflection film 21, that is, the optical axis of the optical finder. 0 Most of the light that has passed through the photographic lens passes through the total reflection film 21 without hitting the total reflection film 21, and is imaged by the remaining photographic lens. On the other hand, since all the light that hits the total reflection film is reflected and enters the optical finder system, the area of the total reflection film is as small as in the conventional example. Further, the total reflection film 21 is connected to the optical axis 2 of the photographic lens.
Since it is located far away from the lens 22, it is possible to use all of the high-quality light flux near the optical axis 22 in terms of aberration performance for photographing, so even when the light flux is narrowed down by the iris diaphragm, the imaging performance of the photographic lens is improved. does not decrease. Further, since the beam sinter 2o shown in the embodiment of the present invention is made of a rectangular parallelepiped glass block, assembly is extremely easy and adjustment is also easy.

The present invention has been described above based on the illustrated embodiments, but
The invention - is not limited to the embodiments described above.

For example, in the above-described embodiment, the total reflection film has a rectangular shape, but a total reflection film having a shape consisting of a part of a circle or a part of an ellipse is also possible.

As is clear from the above description, the present invention can provide a beam splitter that is small, lightweight, and easy to assemble and adjust, which is made of parallel flat glass with a small-area total reflection film provided inside. , the effect is very profound.

[Brief explanation of the drawing]

Figure 1 (A), (B), (C1 is a plan view, front view and side view of a conventional example of a beam splitter, Figure 2 (
A), (B). (q is a plan view, a front view, and a side view of an embodiment of the present invention. 20...0 parallel flat glass, 21... total reflection film. Name of agent: Patent attorney Nakao Toshio and 1 other person 1st
Figure 2

Claims (1)

[Claims] Parallel flat glass having a total reflection film inside thereof is arranged so that light transmitted through the photographing lens system or a part of the lens system constituting the photographing lens system is guided to the optical finder system by the total reflection film. . A beam splitter, characterized in that the total reflection film within the parallel flat glass is disposed at a position away from the optical axis of the photographing lens.