JPS6252477A - Optical system for optical range finder - Google Patents

Abstract

PURPOSE:To efficiently condense receiving luminous flux, by placing a prism behind an objective lens and reflecting the receiving luminous flux from the entire surface of the objective lens from the reflective surface of a reflective prism. CONSTITUTION:A focus matching prism 3 is placed behind an objective lens 1 and a composite prism consisting of a reflective prism 10 and a dichroic prism 2 is placed behind said prism 3. The emitted luminous flux from the infrared source 6 provided in opposed relation to a dichroic mirror 8 is reflected from the mirror 8 to be passed through a luminous flux passing hole while the reflected luminous flux is sent as shown by an arrow through a focus- matching lens 3 and the objective lens 1. The receiving luminous flux through the entire surface of the objective lens 1 and the focus-matching lens 3 is reflected from the reflective surface 11 of the reflective mirror 10 as it is to be condensed to a light receiving element 9. By this method, the receiving luminous flux is efficiently condensed and luminous fluxes for transmission reception are separated to make it possible to prevent stray light.

Description

[Detailed Description of the Invention] [Object of the Invention] Industrial Application This invention provides an objective lens that can be used both for transmitting light and for receiving light. Regarding an optical system for distance measurement and reference using a new composite prism that makes it possible to separate the luminous flux into light transmitting, light receiving and reference use in a coaxial type light wave rangefinder that uses coaxial reference.1 be.

Conventional technology: In the optical system for the optical rangefinder in this building, one side of the semicircle of the objective lens is used for transmitting light and the other side is used for receiving light. In addition to providing a ranging optical system, various types of reference optical systems are also configured.

There are also systems in which this reference optical system is separate from and parallel to the ranging optical system! One reason why 1frt is complicated is that in order to make it more compact, a dichroic mirror is placed in the ranging optical system to separate the light beam into one for ranging and one for reference.

An example of the optical system of such a conventional coaxial light wave range finder will be explained below with reference to FIG. That is, objective lens 1
A dichroic prism 2 is placed on the rear optical axis of the lens, and a focusing lens 3, a true text prism 4, a focusing plate, and an eyepiece 5 are arranged behind the dichroic prism 2 to form a reference optical system. At this time, the reference light beam passes through the objective lens 1 as shown in FIG.
The light that passes through the dichroic mirror 8 that transmits visible light and reflects infrared light that is installed obliquely within the dichroic prism 8 is observed.

On the other hand, in the ranging optical system, the infrared light from the light source 6 is reflected by the dichroic mirror 81 via the prism 7, and then transmitted via the objective lens 1, and the received light beam is reflected by the dichroic mirror 8 after passing through the objective lens 1. The light is then focused on the light receiving element 9.

In such a conventional optical system, only one half of the objective lens 1 is used for receiving light, so the utilization rate of the received light beam for the objective lens 1 is low and the light collection efficiency is poor, making it difficult to measure distance. This is an obstacle to expanding and securing the scope. Also,
In order to prevent stray light that impairs light reception accuracy, measures such as installing a separating plate to separate the transmitted and received light beams on the receiving and transmitting sides, or attaching a stray light prevention plate to the objective lens 1 (none of these are shown)
There was a dislike of complicating the equipment required. moreover,
The received light flux used is asymmetrical, which is undesirable from the point of view of precision construction.

Problems to be solved by the invention...Song...Song This invention was made to solve the problems of the prior art. It is an object of the present invention to provide an optical system for a light wave range finder with a simple structure, which is capable of condensing light and separating both transmitting and receiving light beams to prevent stray light.

[Structure of the invention]

Means to solve problems・・・・・・・・・・・・
...In order to achieve the above object, the present invention utilizes a characteristic composite prism made by joining a reflecting prism with a hole for passing a light beam and a dichroic prism having a dichroic mirror, to achieve distance measurement. It is possible to create a structure in which both the sending and receiving light beams and the reference light beam are separated, that is, the transmitted light beam is reflected by the dichroic mirror and then transmitted through the light beam passing hole of the reflecting prism, and the received light beam is transmitted through the reflecting prism. The reflective surface of the dichroic mirror was used to reflect and condense the light, and the standard visible light beam passed through the light beam passage hole and was transmitted through the dichroic mirror. Then, this composite prism was placed behind the objective lens so that the light beam received from the entire surface of the objective lens was reflected by the reflecting surface f of the reflecting prism and focused, thereby increasing the light collection efficiency. Furthermore, by placing a focusing lens between the objective lens and the compound prism to narrow down the light flux passing through the light flux passing hole, the light flux passing through the hole can be made smaller to prevent a decrease in the utilization rate of the received light flux. This is what I did.

〔Example〕

FIG. 4 shows the construction of an embodiment of the present invention, in which a focusing lens 3 is placed behind the objective lens l, and a compound prism consisting of a reflection prism IO and a dichroic prism 2 is placed behind it. The composite prism is a reflective prism 10
The side surface 12 of the dichroic prism 2 is joined to the side surface 14 of the dichroic prism 2, and the dichroic prism 2 has two divided prisms 2a.
The flesh-and-skin radiation surface of .degree. 2b was joined together, and a dichroic mirror 8 that reflected infrared light and transmitted visible light was formed on this joint surface using a known technique. The reflective prism 10 is provided with a small hole, which is a light beam passage hole 13, which penetrates the reflective surface 11 and the side surface 12 by laser machining or the like, and the reflective surface 11 is formed with an external reflecting mirror.

? Next, the transmitted light beam from the infrared light source 6 installed opposite to the dichroic mirror 8-8 is reflected by the mirror 8-e1, passes through the light beam passing hole 8, passes through the focusing lens 3 and the objective lens 1, and then reaches the point indicated by the arrow. At the same time, the received light flux that has passed through the entire surface of the objective lens 1 and the focusing lens 3 is directly reflected from the reflective surface 111 of the reflective prism 10 and condensed onto the light receiving element 9 for distance measurement. Configure the optical system for use. And objective lens 1
The reference visible light flux that has passed through is focused by the focusing lens 3ffi, passes through the light flux passage hole 13, passes through the dichroic mirror 8, and passes through, for example, an erecting prism, a focus plate, and an eyepiece to form a reference optical path. Configure the system.

Although it is possible to place the focusing lens 3 at the rear of the compound lens lens, by placing it at the front, the diameter of the luminous flux aperture 13 can be made smaller as described above, and it is also possible to focus each luminous flux simultaneously. ing.

〔effect〕

From the above explanation, it is clear that if the present invention is used, the received light beam can be efficiently focused, stray light can be effectively prevented, the range of distance measurement can be extended, and the cone beam that should be placed at the target point can be effectively used. This makes it possible to realize a distance measurement method that eliminates two picks. Moreover, since coaxial focusing can be achieved without the need for stray light prevention means, which was conventionally required, the apparatus becomes simple.

[Brief explanation of drawings]

1(8) is an optical path diagram showing the essential parts of the present invention, and FIG. 2 is an optical path diagram of a conventional type. 1... Objective lens, 2... Dichroic prism, 3...
・・Focusing lens, 8・・Gemicroic mirror, IO
...Reflection prism, 13...Light flux passing hole, 11...
・Reflective surface 0 Figure 1 2 Male figure 2

Claims (1)

[Claims] In a coaxial optical rangefinder in which an objective lens 1 is used for transmitting and receiving light, a focusing lens 3 is placed behind the objective lens 1, and a reflecting prism 10 and a dichroic prism 2 are placed behind it.
The side surface 12 of the reflecting prism is provided with a light beam passing hole 13 passing through the reflecting surface 11 and the side surface 12 of the reflecting prism, and the side surface 14 of the dichroic prism 2 has a dichroic mirror 8 therein. The light flux from the light source is reflected by the dichroic mirror 8, passes through the light flux passage hole 13, and passes through the focusing lens 3 and objective lens 1. The received light flux passes through the objective lens 1 and the focusing lens 3, is reflected by the reflective surface 11 of the reflective prism 10, and is focused on the light receiving element 9 by a distance measuring optical system and the objective lens 1. An optical system for a light wave rangefinder, comprising a reference optical system formed such that the reference light beam that has passed through the focusing lens 3 passes through the light beam passage hole 13, is transmitted through the dichroic mirror 8, and is received. .