JPS5855812A - Laser distance measuring device - Google Patents

Abstract

PURPOSE:To make the device compact and light weight, by sharing a laser collimator, a polarization converting means, and a beam splitting polarizer, as a light receiving optical system which introduces the reflected light from a target into a light detector. CONSTITUTION:The reflected light of laser light is inputted into the light detector 18 through an objective lens 22 as the laser collimator, a dichroic mirror 20, a concave lens 24, rectangular prisms 23 and 21, the beam splitting polarizer 13, and a converging lens 17. The laser light outputted from the beam splitting polarizer 13 to the rectangular prism 21 is totally reflected four times until it is inputted to the beam splitting polarizer 13 again. Therefore it is linearly polarized again. However, since its plane of polarization forms a right angle with the plane of polarization of the beam splitting polarizer 13, the reflected light can be introduced into the optical detector 18 with almost no polarizing loss.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser range finder having a Q-switched laser device tube transmitter that emits giant pulse oscillations. An example of a system diagram of a conventional laser range finder is shown in FIG.

In this laser distance measuring device, a q-switch laser device 1
The laser beam output from the collimator 2 spreads the beam to a smaller size and irradiates it to the target. At this time, aiming at the target is performed using sighting glasses Jt- which have been parallax adjusted in advance and have friends Ba=Set. .

The reflected light from the target is received by the receiving optical system 3.

When outputting a laser pulse, the pulse (pulse 1) output from the Q-switch laser device 1 and the pulse (pulse 2) output from the detection 1ijb when receiving reflected light are input to the ranging signal processing and display circuit 4. The 0 distance measurement signal processing and display circuit 4 measures the time delay of the Norms output from the Q-switched laser device 1, calculates the distance to the target, and displays the distance from 0 to the target as shown in FIG. 0 Generally, in a laser range finder, in order to increase the distance measured without changing the laser output, the light receiving diameter (i.e., the receiving optical system 30 objective lens ja) must be increased. There is a need. In order to simultaneously concentrate as much laser light as possible on the target, the collimation ratio of collimator 2 is increased, that is,
It is necessary to increase the objective lens Jai. As a result, the laser distance measuring device having the configuration shown in FIG. 1 has the drawback of being large and heavy.

This invention was made to eliminate the above-mentioned conventional drawbacks, and includes an optical system used as a laser collimator to introduce reflected light from a distance measurement target into a photodetector, a polarization conversion means, and a beam beam. It is an object of the present invention to provide a laser distance measuring device that can be made compact and lightweight since it can be used in common with a split polarizer.

Hereinafter, an embodiment of the laser distance measuring device of the present invention will be explained based on the drawings.0 Fig. 2 is a diagram showing the configuration of one embodiment.0 In this Fig. 2, numeral 11 is a roof prism; Prism 11, right angle prism 12,
A laser medium 15 and a Pockels cell 15 are arranged in an optical resonator formed by a beam splitting polarizer 13 and a prism 14, and an OQ switch laser device is configured as a laser light pulse oscillation device.

Here, the prism 14 is selected so that the roof prism 1 and the rectangular prism having an optical path bending plane perpendicular to the ridgeline of the roof prism 11 are combined together to have a tube with the following shape, and the planes of polarization of the incident light and the reflected light are the same. It is a prism with a refractive index of This prism 14 has the same performance as the roof prism 11 in terms of geometrical optics, and has the same properties 1 as a parallel plane mirror in terms of polarization.

The prism 14, Pockels cell 16, beam splitting polarizer 13, condensing lens 11, and photodetector 18 are arranged on the same axis. Loic Miller 20. Objective lenses 22 are arranged on the same axis.

A right-angle prism 23 is arranged opposite to the right-angle prism 21, and this right-angle prism 23 and a concave lens 24
The mirror 1 and the microchroic mirror 20 are arranged on the same axis.

Laser output light from the Q-switched laser device is converted from linearly polarized light to circularly polarized light by a right angle prism 21 and a right angle prism 23 as polarization conversion means. This circular polarization is performed by making full use of the phase shift in the total reflection of the right angle prisms 21 and 23. Therefore, the polarization plane of the beam splitting polarizer 13 and the optical path bending planes of the right-angle prism 21 and the right-angle prism 23 are arranged so that they intersect at an angle of 45 degrees. The angle of incidence of the laser beam on the reflective surface is 45°.The right-angle prism 23 and the right-angle prism 2, which are arranged in such a way, have a refractive index in the range of 1°554±0.010. It is made of material that has. In this way, the polarization conversion means can be constituted by two right-angle prisms 21, 21, but it can also be constructed by using a prism plate in which two right-angle prisms are integrated.

Although not shown in FIG. 2, the output of the photodetector 18 is sent to the ranging signal processing and display circuit in the same manner as in FIG. 1, where the distance to the target is measured. It is designed to be displayed.

Next, the operation of the laser distance measuring device of the present invention configured as described above will be explained. The laser beam is output from the objective lens 22 as almost completely circularly polarized light. In normal cases, the laser beam irradiated onto an object (not shown) is
The plane of polarization is reflected almost unchanged. In other words, it can be considered to have properties similar to a parallel plane mirror in terms of polarization. The reflected light of this laser beam is transmitted through an objective lens 22 as a laser collimator, a guichroic mirror 201, a concave lens 24, a right-angle prism 21. The laser beam outputted from the beam splitting polarizer 13 to the right angle prism 21 is beam split and polarized again as reflected light. Since the light undergoes total reflection four times before being input to the device 13, it becomes linearly polarized light again, but since its plane of polarization is perpendicular to the plane of polarization of the beam splitting polarizer 11, it is all reflected to the condenser lens 1r.

In other words, the photodetector 1 receives almost no polarized ps.
Reflected light can be introduced into B.

Note that the objective lens 22 and the aiming optical system 11 constitute aiming glasses. And the objective lens 2 of the laser collimator
2 can also be used as sighting glasses for aiming at a distance measuring target or as an objective lens for a TV camera.

As mentioned above, if the laser distance measuring device of this invention is used,
Since the laser collimator L, the polarization conversion means, and the beam splitting polarizer are used together as a receiving optical system that introduces the reflected light from the target to the photodetector, it can be made small and lightweight.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional laser distance measurement device, and 21PQ is a diagram showing the configuration of an embodiment of the laser distance measurement device of the present invention.

Claims (1)

[Claims] A laser light pulse oscillation device that outputs linearly polarized laser light from a beam splitting polarizer, a polarization conversion means that converts the linearly polarized laser light from the laser light pulse oscillation device into circular polarization, and the polarization conversion means. circularly polarized laser beam t
An optical system that collimates and irradiates the target object, a photodetector that detects reflected light from the target object, and a means that is supplied with an output signal of the photodetector and calculates and displays the distance to the target object. and a metal fitting, and the reflected light from the target object is guided to the photodetector via the optical system, the polarization conversion means, and the beam splitting polarizer.