JPS60139037A - Laser light transmitter - Google Patents

Abstract

PURPOSE:To stabilize the laser light in the direction of the transmitting optical axis by using a means which detects the radiating direction of the laser light and a means which can change continuously the transmitting beam direction of the laser light. CONSTITUTION:The laser light delivered from a laser oscillator 2 is made incident to an optical deflector 20 which can change continuously the direction of the light. Then the laser light is made incident to a beam splitter 21 from the deflector 20. A part of the light made incident to the splitter 21 is made incident to an angle detector 22, and the greater part of said light is sent to a target via a transmission optical system 3. Then the detector 22 detects the radiating direction of the laser light and sends the angle signal to an arithmetic controller 23. The controller 23 calculates a displacement degree from the prescribed transmission beam direction by the signal given from the detector 22. Then the deflector 20 is controlled by the displacement degree signal to set the displacement degree at zero. Thus it is possible to stabilize the laser light in the direction of the transmitting optical axis.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to improvement of a laser beam transmitting device, and provides a predetermined transmitting device regardless of fluctuations in the emission direction of the laser beam generated from a laser oscillator. It is something.

[Prior Art] A laser distance measuring device is a common example of a laser beam transmitting device. A laser distance measuring device measures distance by measuring the time it takes for a pulse of laser light to travel back and forth to a target. FIG. 1 shows an example of the configuration of a laser distance measuring device.

The laser oscillator (21) of the laser beam transmitter (1) oscillates a gigantic pulsed light, and most of this oscillated light is sent to the transmitting optical system (21).
3) From K, set a predetermined beam spread to 9 angles and fire toward the target object. In addition, a part of the oscillated light enters the photodetector (4), and the electric signal is sent to the counter (5) as a start pulse.
and the counter starts counting clock pulses from the clock pulse oscillator (6).

On the other hand, the light reflected by the visible object is transmitted to the receiving optical system (71
It passes through a filter (8) for removing background light noise and the like to a photodetector (9). -φ+□- is formed and added to the counter gate of the counter (5) as a stop pulse. The number of clock pulses counted during the opening/closing time of the gate by the start pulse and stop pulse is converted into a distance, and the distance value is displayed on the display (1).

By the way, it is necessary to fit the transmitting laser spot on the target object within the field of view of the receiving optical system 171, and in order to further reduce background light noise, the field of view must be narrowed to the extent that the beam of the transmitting laser light spreads at a polygonal angle. There is a need to. For this purpose, the optical axis of the transmitting optical system (3) (transmission beam direction of the laser beam), the optical axis of the receiving optical system (7;), and the optical axis of the aiming telescope 03 used for aiming at the target object are strictly Must match.

Q-switched solid-state lasers, which generate high output and extremely short pulses, are usually used as lasers for laser distance measuring devices in terms of reachability and distance measurement accuracy. FIG. 2 shows an example of a conventional configuration of a laser beam transmitter in this case. In the figure, 113 is a laser rod, and t14 is a polarizer.

Pockels cell of asuq switch element, fl[9d7
The lash lamp, αn is a total reflection mirror, and a8 is an output mirror.

The laser beam is a reflector tube that effectively focuses the light from the flash lamp ae onto the laser rod (13), and these constitute the laser oscillator (21).In addition, in the case of a high-repetition pulse laser, the laser rod (13 and the flash lamp Usually, aQ is forcibly cooled by liquid or gas.

The laser beam emitted from the laser oscillator is sent to the transmission optical system (3)
K is incident, the beam spread is adjusted to a predetermined polygonal angle, and the beam is transmitted. Arrow A indicates the transmit beam direction. As this transmitting light Ushibuka (3), an inverted Galilean telescope consisting of a concave lens and a convex lens is often used.If the magnification of this telescope is M, the beam spread angle θ of the laser light emitted from the laser oscillator is The relationship between the optical system (3), that is, the beam spread polygon (2) transmitted from the telescope is expressed by the following equation.

θ ■=M +I+ Also, the emission direction of the laser beam from the laser oscillator is at an angle △θ
The amount of change Δ0 in the direction of the laser beam transmitted from the transmitting optical system (3) when the direction of the laser beam is changed by Δ0 is expressed by the following equation.

Δ(1 move=M (21) By the way, a laser distance measuring device applied to an optical tracking device etc. requires high repetition rate laser oscillation.

As mentioned above, forced cooling of the laser rod 03 of the laser oscillator (2) and the flash lamp ae is required. In this case, due to the relationship between the cooling in the laser rod (c) K and the generation of heat due to the absorption of light from the flash lamp, a temperature distribution occurs within the laser rod +13, causing thermal effects such as a thermal lens effect, and the laser beam 'JIK influence. As a result, the emission direction of the laser beam from the laser oscillator (21) may change over time. This phenomenon occurs particularly when the cooling and excitation of the laser rod 0 are uneven. Also, the output The inclination of the mirror Al may change and the direction of laser beam emission may become concave. When the direction of emission of laser light from the laser oscillator (2) changes over time as described above, in a laser distance measuring device, The direction of the transmitting beam may deviate from the direction of the receiving optical axis and the aiming direction of the target object.Therefore, the receiving ability may be reduced or the target object may not be irradiated with the laser beam, and the stable performance of the laser ranging device may be affected. You won't be able to get it.

As described above, the conventional laser beam transmitting device has the disadvantage that if the direction of the laser beam emitted from the laser oscillator changes, the direction of the transmission beam transmitted from the transmitting device also changes.

One way to improve this is to increase the magnification M of the transmission optical system (3), as shown in equation (2). However, as shown in equation I), this also affects the spread angle of the transmitted laser beam and is therefore subject to restrictions. Furthermore, increasing the magnification of the transmitting optical system has the disadvantage that the optical system has a large aperture, making the system larger.

[Summary of the invention]

The present invention has been made with the aim of correcting such drawbacks, and includes a means for detecting the direction of laser light emitted from a laser oscillator, and a means for continuously changing the direction of the transmitted beam of the laser light based on the output of this detection means. Equipped with means for variable control,
The direction of the transmission optical axis of the laser beam is stabilized.

[Embodiments of the invention]

FIG. 8 is a diagram showing an embodiment of the present invention. The laser beam emitted from the laser oscillator (21) enters the optical deflector (A) that can continuously change the direction of the light. The laser beam emitted from the optical deflector circle enters the beam sinter 6111, and a portion of the laser beam is It is reflected and enters the angle detector (2), and most of it is transmitted to the target object through the transmission optical system (3).

By the way, if the emission direction of the laser beam emitted from the laser oscillator (2) changes over time, the beam direction of the laser beam to be transmitted can be changed by changing the deflection angle of the optical deflector (to) in accordance with the change. can be kept constant.

The angle detector detects the direction of the laser beam emitted from the laser oscillator (2) and sends the angle signal to the arithmetic controller (c). Arithmetic controller (c) is angle detector (2)
The amount of displacement from a predetermined transmission beam direction is calculated from the signal from , and the optical deflector (a) is controlled based on the displacement amount signal so that this amount of displacement becomes zero.

FIG. 4 shows an example of the angle detector (2).

In FIG. 4, a small amount of light reflected by the beam splitter t2D enters the condenser lens C241. Condensing lens +
A light spot position detector cl! is placed on the focal plane of 241. Install 9. As a light spot position detector, a semiconductor device detector using a silicon photodiode is commercially available. The angular displacement of the laser beam incident on the condenser lens (to) can be measured as the displacement of the light spot position on the light spot position detector (2).

A signal of this displacement amount, that is, an angular displacement signal in the emission direction of the laser beam is sent to the arithmetic controller@.

Fig. 5 shows an embodiment of the optical deflector (A).The laser beam emitted from the laser oscillator (2) consists of a reflecting mirror (1) and another reflecting mirror (2). The reflection mirror (C) is continuously tilted by an electrostrictive element (2) to deflect the laser beam in the vertical direction. The tilt is changed to horizontally deflect the laser beam.According to the signal from the arithmetic controller @, the deflection controller (7) controls the tilt of each of the reflecting mirror (A) and the reflecting mirror surface, and the laser beam is deflected to a predetermined direction. Send in the direction of.

In the above description, a Q-switched solid-state laser was used as an example, but the present invention may also be used in a laser beam transmitting device such as a gas laser or a semiconductor laser.

[Effects of the Invention] As described above, the laser beam transmitting device according to the present invention is equipped with a means for detecting the direction of laser beam emission and a means for continuously changing the direction of the transmitted beam of the laser beam. Even if the laser beam emission direction fluctuates due to various causes, the laser beam can be transmitted in a predetermined transmission beam direction, and the transmission beam remains stable.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a laser distance measuring device. FIG. 2 is a block diagram of a conventional laser beam transmitter, FIG. 8 is a diagram showing an embodiment of the present invention, FIG. 4 is a diagram showing an embodiment of an angle detector, and FIG. 5 is a diagram of an optical deflector. It is a figure showing an example. In the figure (11 is a laser beam transmitter, (21 laser oscillators, (3) is a transmission optical system, (1) is an optical deflector, C1l+
is a beam sinter, (to) is an angle detector, and (c) is an arithmetic controller. In addition, the same or corresponding parts in each figure are indicated by the same reference numerals. Agent Masuo Oiwa Figure 3 Figure 4 Figure 2/

Claims (1)

[Claims] In a laser beam transmitting device comprising a laser oscillator and an optical system that transmits the laser beam generated from the laser oscillator to a target object with a predetermined beam spread of 9 angles, one of the laser beams generated from the laser oscillator is emitting the laser beam generated from the laser oscillator, the laser beam is emitted from the laser oscillator. A laser beam transmitting device characterized by compensating for directional fluctuations.