JPH0511082U - Laser light transmission / reception optical system - Google Patents

Abstract

(57) [Abstract] [Purpose] An object is to provide a laser light transmission / reception optical system capable of receiving reflected light from a short-range target without changing the reception characteristics for the long-range target. [Structure] A circular opening h ₁ centered on the optical axis at a focus position of a receiving optical system, and a slit-shaped opening from the edge of the circular opening h ₁ opposite to the transmitting optical system side in a direction opposite to the transmitting optical system side. h
A light shielding plate 4 provided with ₂ is arranged to constitute a laser light transmitting / receiving optical system.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a laser beam transmitting / receiving optical system for receiving a laser beam with a limited field of view in a laser range finder.

[0002]

[Prior Art]

 Conventionally, there are laser light transmitting / receiving optical systems shown in FIGS. FIG. 4 is a diagram showing the configuration and usage of the laser transmission / reception optical system, FIG. 5 is a diagram showing the opening shape of the pinhole, and FIG. 6 is a diagram showing the relationship between the reception field of view and the coverage area of the transmission beam. In FIG. 4, 1 is a laser oscillator, 2 is a transmitting optical system, 3 is a receiving optical system, 4 is a light blocking plate having a pinhole H, and 5 is a light receiving element. In FIG. 5, H is the opening of the pinhole. In FIG. 6, reference numeral 6 is a reception field of view, 7 is a coverage area of the transmission beam, 7a is a coverage area when the target is at a distance, 7b is a coverage area when the target is at a medium distance, and 7c is a coverage area. Shows the coverage area at close range.

Next, the operation will be described. In FIG. 4, the laser light emitted from the laser oscillator 1 enters the transmission optical system 2 and, after adjusting the transmission beam divergence angle, is transmitted toward an external target. The reflected light from the target is condensed by the receiving optical system 3, passes through the pinhole H, and then enters the light receiving element 5.

As shown in FIG. 5, the pinhole H is a circular aperture, and the reception viewing angle is d / f, where d is the aperture diameter and f is the focal length of the reception optical system.

By arranging the transmission optical system 2 and the reception optical system 3 in parallel, the center of the reception field of view and the center of the transmission beam coverage can be made to coincide with each other, and the reception viewing angle can be made approximately equal to the transmission beam divergence angle. By doing so, it is possible to remove external light other than the reflected light of the transmitted laser light by the target.

[0006]

[Problems to be solved by the device]

 Since the conventional transmission / reception optical system is configured as described above, when the target is at a long distance, it is possible to overlap the coverage of the reception field of view and the coverage of the transmission beam on a concentric circle, and to obtain external light other than the reflected light from the target. The reflected beam from the target can be received efficiently, but when the distance to the target becomes short, the coverage area of the transmission beam is changed from the center of the reception field due to the parallax effect of the transmission optical system and the reception optical system. It shifts in the direction opposite to the direction in which the transmission optics are arranged, and finally moves out of the reception field of view. Therefore, there was a problem that the reflected light from the target could not be received even if there was a target at a short distance. This state is shown in FIG.

The present invention was made in order to solve the above-mentioned problems, and it is possible to receive reflected light from a target even when the target is in a short distance, and when the target is in a long distance. It is an object of the present invention to provide a laser light transmitting / receiving optical system that has an effect of removing external light other than the reflected light from the target.

[0008]

[Means for Solving the Problems]

 In the laser light transmission / reception optical system according to the present invention, a circular aperture centered on the optical axis is formed at the focus position of the reception optical system, and a direction opposite to the transmission optical system side from the edge of the circular aperture opposite to the transmission optical system side. In addition, a light shielding plate provided with a slit-shaped opening is arranged.

[0009]

[Action]

 In the laser light transmitting / receiving optical system according to the present invention, a slit-shaped opening is provided in the direction opposite to the transmitting optical system side from the edge of the circular opening opposite to the transmitting optical system side. Also, the reflected light from the target passes through the aperture. Moreover, since the slit portion is thin, it is possible to remove outside light other than the reflected light from the target for a distant target.

[0010]

【Example】

Example 1. An embodiment of this invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration and structure of a laser transmission / reception optical system of the present invention, FIG. 2 is a diagram showing the aperture shape of a light shielding plate, and FIG. 6 is a diagram showing the relationship between the reception field and the coverage area of the transmission beam. In FIG. 1, 1 is a laser oscillator, 2 is a transmitting optical system, 3 is a receiving optical system, 4 is a light-shielding plate having an opening, and 5 is a light receiving element. In FIG. 2, H is an opening of the light shielding plate, and a circular opening h ₁ centered on the optical axis and a slit from the edge of the opening h _{1 on} the side opposite to the transmission optical system side in the direction opposite to the transmission optical system side. Has an opening h ₂ . In FIG. 3, 6 is the reception field of view, 7 is the coverage of the transmitted beam, 7a is the coverage when the target is at a distance, 7b is the coverage when the target is at a medium distance, and 7c is the coverage. Shows the coverage area at close range.

Next, the operation will be described. In FIG. 1, a laser beam emitted from a laser oscillator 1 enters a transmission optical system 2 and, after adjusting a transmission beam divergence angle, is transmitted toward an external target. The reflected light from the target is condensed by the receiving optical system 3, passes through the light shielding plate 4 through the opening H, and then enters the light receiving element 5.

As shown in FIG. 3, when the target is distant, the coverage area 7a of the transmission beam overlaps with the circular opening on the concentric circle, and the opening area of the slit portion is narrower than the opening area of the circular portion. Similar to the pinhole of the laser light transmitting / receiving optical system, it has the effect of transmitting the reflected light from the target and blocking the external light in the peripheral area. When the target is at a medium distance, the coverage 7b of the transmission beam is displaced from the center of the circular aperture, but the operation is the same as when the target is at a long distance. When the target is in a short distance, the coverage 7c of the transmission beam goes out of the circular aperture and overlaps the slit portion, and the reflected light from the target partially passes through the slit. Since the target is at a short distance, even if only a part of the reflected light passes through, the energy required for the light receiving element to operate can be obtained.

[0013]

[Effect of the device]

 As described above, according to the present invention, since the slit-shaped opening is provided in the light shielding plate from the edge of the circular opening on the side of the transmission optical system, in the direction opposite to the side of the transmission optical system, reflection from a target at a distance is achieved. It is possible to receive reflected light from a target at a short distance without changing the light receiving performance.

[Brief description of drawings]

FIG. 1 is a diagram showing a laser light transmitting / receiving optical system according to an embodiment of the present invention.

FIG. 2 is a view showing a light blocking plate having an opening according to an embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a reception field of view and a coverage area of a transmission beam according to an embodiment of the present invention.

FIG. 4 is a diagram showing a conventional laser light transmitting / receiving optical system.

FIG. 5 is a diagram showing a conventional pinhole.

FIG. 6 is a diagram showing a relationship between a conventional reception field of view and a coverage area of a transmission beam.

[Explanation of symbols]

 2 Transmission optical system 3 Reception optical system 4 Light shield

Claims (1)

Claims for utility model registration: 1. A laser beam transmitting / receiving optical system comprising a transmitting optical system and a receiving optical system arranged such that their optical axes are parallel to each other. A laser beam characterized by arranging a circular aperture centered on the axis and a light shielding plate provided with a slit-shaped aperture in a direction opposite to the transmission optical system side from the edge of the circular aperture opposite to the transmission optical system side. Transmission and reception optics.