JPH0792310A - Reflecting prism for enlarging beam - Google Patents

Abstract

PURPOSE:To emit a light making the beam diameter as large as possible by providing a function which enlarges the beam diameter of an incident light at a reflecting prism. CONSTITUTION:An incident plane 2, reflecting surface 3, and light-emitting surface 4 are formed at a prism main body 1. A convex spherical mirror part 3a of which convex spherical surface enters the prism main body 1 is formed at the central part of the reflecting surface 3. A light made incident from the incident plane 2 on the prism main body 1 is reflected on the convex spherical mirror part 3a, so that the beam can be enlarged. Also, the site of an optical path from the reflecting part of the convex spherical mirror part 3a to the light-emitting surface 4 in the prism main body 1 is provided with a function as a concave lens, so that the beam diameter of the light emitted from the light-emitting surface 4 can be made extremely larger than that of the incident light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam expanding reflection prism used as an optical element.

[0002]

2. Description of the Related Art A reflection prism is made of triangular thick optical glass having an entrance surface, a reflection surface and an exit surface, and light incident from the entrance surface is reflected by the reflection surface.
The optical path is changed and the light is emitted from the emission surface, and is used as an element for changing the direction of the optical path in the optical system.

[0003]

By the way, there are various types of optical elements, and in addition to the one that changes the direction of the optical path like a reflection prism, for example, an optical element for beam expansion for expanding the beam diameter is available. is there. However, the optical element for changing the direction of the optical path and the optical element for expanding the beam diameter are separate elements, and these optical elements are sequentially arranged along the optical path. Further, there are a lens and a convex mirror as typical ones of the beam expanding element, but due to the aberration and the like, the beam diameter cannot be extremely expanded by these lenses and the convex mirror alone.

The present invention has been made in view of the above points, and an object thereof is to provide a beam expanding reflection prism having a function of expanding a beam to a necessary degree. .

[0005]

In order to achieve the above-mentioned object, the present invention has a prism body having an incident surface, a reflection surface and an emission surface for light, and the reflection surface of the prism body has a spherical shape. The feature is that the configuration is such that the convex mirror portion composed of the convex portions is formed.

[0006]

The light incident from the incident surface is reflected by the reflecting surface. Since the reflecting surface has a convex portion, it functions as a convex mirror. Therefore, when reflected by the reflecting surface, the optical path direction changes and the beam diameter of the incident light expands according to the curvature of the convex surface portion. Moreover, since the optical path from the reflecting surface functions as a concave lens inside the prism, the beam diameter is further expanded and emitted from the prism. As a result, the function of expanding the beam can be exerted in addition to the function of changing the optical path direction. Moreover, since the beam expanding function is a combination of a convex mirror and a concave lens, it is possible to perform a sharp beam expansion.

As described above, the beam expanding reflection prism according to the present invention has three functions of changing the direction of the optical path, functioning as a convex mirror, and functioning as a concave lens. Compared with the case where two optical elements are provided, the optical axis adjustment and the like become easier and a compact optical design becomes possible. Moreover, since the reflecting surface of the convex mirror is not exposed to the outside, the reflecting surface is protected and there is no risk of damage or the like.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a cross section of the prism. In the figure, reference numeral 1 denotes a prism body made of optical glass, a surface 2 of the prism 1 is an incident surface, and a reflecting surface 3 is provided at an angle of 45 ° with respect to the incident surface 2, and The emission surface 4 is formed at an angle of 45 ° with respect to the reflection surface 3. The reflecting surface 3 is not a flat surface, but its central portion is a convex spherical mirror portion 3a having a convex spherical shape that is inserted into the prism body 1. Then, the entire reflecting surface 3 including the convex spherical mirror portion 3a,
A reflective film 10 is applied as shown in FIG. 2, and a protective layer 11 is further laminated on the reflective film 10. The protective layer 11 is formed over the entire surface including the concave portion where the convex spherical mirror portion 3a is formed. Therefore, the reflecting surface 3 side is entirely flat.

The prism of this embodiment is constructed as described above, and its operation will be described below. This prism is a reflecting prism having a reflecting surface 3, and when light is made incident from the incident surface 2, it is reflected by the reflecting surface 3, the optical path is changed by 90 °, and the light is emitted from the emitting surface 4. Therefore, this prism functions as an optical element for changing the direction of the optical path. Further, the reflecting surface 3 has a convex spherical mirror portion 3
Since a is formed, the incident light is reflected by the convex spherical mirror portion 3a.
By reflecting on, the beam exhibits its function as a convex mirror that expands the beam. Further, the portion of the optical path from the reflecting portion of the convex spherical mirror portion 3a to the exit surface 4 in the prism body 1 has a function as a concave lens. Therefore, the beam diameter of the light emitted from the emission surface 4 is extremely large with respect to the incident light. Further, if a material having a high refractive index is used as the material of the prism body 1, the effect of expanding the beam diameter is further enhanced.

As described above, this prism has the function of changing the direction of the optical path and the function of expanding the beam of the incident light, and the beam expanding function includes a convex mirror and
It becomes a combination with a concave lens, and the beam can be expanded rapidly. Since one prism is made to have the functions of these three optical elements, only one prism needs to be assembled in the optical path, so that the three optical elements respectively face the optical path. The optical system can be designed very easily and the optical path length can be remarkably shortened as compared with the above-mentioned assembly. In addition, the reflecting surface 3 having a function as a convex mirror
Since the reflected light is immediately incident on the concave lens without an air gap, the element itself can be made compact as compared with the case where the reflected light is incident on the concave lens with an air gap from the convex mirror. Further, since the convex spherical mirror portion 3a of the reflecting surface 3 which functions as a convex mirror is inside the prism body 1 and is not exposed to the outside, the convex spherical surface 3
There is no risk of scratches on the product and its protection is achieved.

[0011]

As described above, according to the present invention, since the convex mirror portion composed of the spherical convex portion is formed on the reflecting surface of the prism body, the function of changing the direction of the optical path to the prism and the beam diameter The function of expanding the beam diameter can be provided, and since the function of expanding the beam diameter is the combination of the convex mirror and the concave lens, the beam diameter can be expanded to be extremely large with a small optical element.

[Brief description of drawings]

FIG. 1 is a sectional view of a prism showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a portion A of FIG.

[Explanation of symbols]

 1 Prism Main Body 2 Incident Surface 3 Reflective Surface 3a Convex Spherical Mirror Section 4 Emitting Surface 10 Reflective Film 11 Protective Layer

Claims (1)

[Claims] 1. A prism main body having an incident surface, a reflection surface, and an emission surface of light is provided, and a convex mirror portion composed of a spherical convex portion is formed on the reflection surface of the prism main body. Reflective prism for beam expansion.