JPS5932935Y2 - Automatic light amount adjustment device for light wave ranging equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic light amount adjustment device in a light wave distance measuring device.

Conventionally, as an automatic light amount adjustment device in a light wave distance measuring device,
Special public 51-8338.51-8339.518340
The one in Publication No. 1 is known.

In these devices, a light amount variable device is provided in the external optical path or the internal optical path, and a feedback circuit is used to adjust the light amount variable device so that the amounts of light passing through the external optical path and the internal optical path are mutually fixed values or within a certain range. is controlled.

However, in such conventional devices, when an electro-optical light control element such as an electrochromic element is used as a light amount variable device, the transmittance of the element may vary locally, which may cause errors in distance measurement values. Therefore, in order to improve measurement accuracy, it is desirable to suppress this influence as much as possible.

An object of the present invention is to provide an automatic light amount adjustment device for a light wave distance measuring device that minimizes the influence of local unevenness occurring in an electro-optic light control element.

The present invention will be described below based on examples.

FIG. 1 shows an embodiment of the present invention.

In FIG. 1, 1 is an oscillator that determines the modulation frequency; 2 is an oscillator that determines the modulation frequency;
is a modulator which receives as input the output of the oscillator 1 which modulates the light from a light source 3 made of a light emitting diode or a semiconductor laser.

The light 4 from the light source 3 modulated by the modulator 2 reaches the transmission optical system 6 via the optical path switch 5 which moves in the direction of arrow A and the direction of arrow B, and also reaches a reflection object 8 as transmitted light 7.
is irradiated.

Reference numeral 9 denotes a filter for condensing the reflected light from the reflecting object 8 by the receiving optical system 10 whose optical axis is parallel to the optical axis of the transmitting optical system, and for removing noise components other than the wavelength of the light source 3. 11, and then passes through an electro-optic light control element 12 and enters a photoelectric converter 13 such as a photodiode.

Amplifiers 14 and 15 have the same specifications, and the output signal of the modulator 2 is branched and applied to the amplifier 14, and the signal from the photoelectric converter 13 is applied to the amplifier 15.

16 is a phase meter which determines the phase difference between the signals output from the amplifiers 14 and 15, and outputs it.

17, the output of the phase meter 16 is transferred to the phase memory 18 and the arithmetic circuit 1;
9 is a signal switching device which switches between the two signals, and 20 is a display device.

21 is a reflecting mirror, and the optical path switch 5 is indicated by arrow B in the figure.
It acts to reflect the light from the light source 3 when moving in the direction.

That is, when the optical path switch 5 moves in the direction of arrow B, the light 4 from the light source 3 does not reach the transmitting optical system 6 but is emitted toward the reflecting mirror 21a.

Therefore, when the light 4 reaches the transmission optical system 6, the optical path switch 5
is in a state where it moves in the direction of arrow A.

22 is a condenser lens that condenses the light reflected by the reflector 21a, and the condensed light is reflected by the reflector 21b and passes through the filter 11 and the electro-optic light control element 12. and enters the photoelectric converter 13.

23 is a set value generator in which the signal level is set in advance; 24 is the output of the amplifier 15 and the set value generator 23;
A comparator 25 uses the output of the comparator 24 as an input to compare the two, and the output of the amplifier 15 and the set value generator 2
It is detected that the output of 3 has a predetermined relationship, and the phase meter 1
6 is an actuator, 26 is an amplifier, and 27 is an amplifier 2.
The electro-optic light control element 1 receives the output of
This is a control circuit that controls 2.

As the electro-optical light control element 12, an electrochromic element or the like whose transmittance changes depending on the magnitude of applied voltage can be used.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

First, by moving the optical path switch 5 in the direction of arrow B in the figure, the light source 3
The light 4 from the reflector 21a, lens 22, reflector 21b
, enters the photoelectric converter 13 via the filter 11 and the electro-optic light control element 12.

Note that the light source 3, the reflecting mirror 21a, the lens 22, and the reflecting mirror 21
A system consisting of the b filter 11, the electro-optic light control element 12, and the photoelectric converter 13 forms an internal optical path, and the photoelectric conversion signal of the light beam passing through the optical path becomes a reference signal.

After this reference signal is amplified by an amplifier 15, a comparator 24
．． It is compared with the signal from the set value generator 23 at .

The comparator 24 outputs a positive or negative signal until the levels of both input signals fall within a predetermined range, and outputs a zero signal when both signals fall within a predetermined range.

The output signal of the comparator 24 is used by an amplifier 26 and a control circuit 27 to control the electro-optic light control element 12.

When the output signal of the comparator 24 becomes zero, the phase meter 16 is activated by the signal from the actuator 25, and the phase difference φB between the output signals of the amplifiers 14 and 15 is obtained as its output.

The phase difference φB is stored in the phase memory 18 via the switch 17 (in the dotted line position).

Next, when the optical path switch 5 is moved in the direction of arrow A as shown in the figure, the switch 17 is moved to the position shown in the figure.

Light 4 from the light source 3 is irradiated onto a reflective object 8 via a transmission optical system 6.

The reflected light 9 from the reflecting object 8 enters a photoelectric converter 13 via a receiving optical system 10, a filter 11, and an electro-optic light control element 12.

Note that the above-mentioned light source 3, transmission optical system 6, reflection object 8, reception optical system 10, filter 11, electro-optic light control element 1
2. Form an external optical path with the photoelectric converter 13.

The output of the photoelectric converter 13, that is, the received signal, is sent to the amplifier 1.
5 to the comparator 24, and is compared with the output level of the set value generator 23 in the same way as the reference signal described above.

The procedure for controlling the electro-optic light control element 12 by the output of the comparator 24 is the same as in the case of the reference signal described above.

When the output signal of the comparator 24 becomes zero, the phase meter 16 is activated by the output of the actuator 25, and the output signal is output from the amplifiers 14 and 1.
A phase difference φ of 5 output signals is obtained.

The phase difference φ is input to the arithmetic circuit 19 via the switch 17.

Since the phase difference φB is also input to the arithmetic circuit 19 from the phase memory 18, the arithmetic circuit 19 calculates the above two phase differences φB.
9. between φB, where f is the amplitude modulation frequency C calculates the speed of light dust in the atmosphere, outputs the optical path length of the light source 3 - reflecting object 8 - detector 13, and the display 20 displays it.

In the above-described embodiment, the electro-optic light control element 12 is disposed immediately before the photoelectric converter 13 so as to include an internal optical path and a partial optical path, as shown in FIG.

Therefore, it is more flexible than a system in which a light intensity variable device is installed in either the internal or external optical path, and requires only one component compared to a system in which a light intensity variable device is installed in both optical paths separately. There are advantages.

Furthermore, since the electro-optical light control element 12 is located just before the photoelectric variable device 13, even if it is configured to include both optical paths, the surface area is extremely small, and the influence of unevenness on the element surface can be almost eliminated. can.

In the embodiment shown in FIG. 1, the electro-optic light control element 12
was constructed as a single member, but as shown in Fig. 2,
The sealing member 31 (usually made of glass) of the semiconductor photoelectric conversion element 30 constituting the photoelectric converter 13 may also be used as an electro-optic light control element.

In this case, the smallest electro-optic light control element can be obtained.

As described above, according to the present invention, since the electro-optic light control element is provided immediately before the photoelectric converter so as to include the internal optical path and the external optical path, one electro-optic light control element is used for the internal optical path. It can also be used for an external optical path, and the surface area of the element can be made small.

Therefore, the influence of local unevenness occurring in the electro-optic light control element on the signal can be reduced.

[Brief explanation of drawings]

FIG. 1 shows one embodiment of the present invention, and FIG. 2 shows another embodiment of an electro-optic light control element. Explanation of symbols of main parts, 3...Light source (internal optical path), 2
1a...Reflector (internal optical path), 22...Lens (internal optical path), 21b...Reflector (internal optical path), 11...
- Filter (internal optical path), 12... Electro-optical light control element (internal optical path), 13... Photoelectric converter (internal optical path), 3... Light source (external optical path), 6... Transmission optics system(
external optical path), 8... reflective object (external optical path), 10...
- Reception optical system (external optical path), 11... filter (external optical path), 12... electro-optic light control element (external optical path), 13... photoelectric converter (external optical path), 24...- Comparator.

Claims (1)

[Claims for Utility Model Registration] 1. A light intensity variable device is interposed in the external optical path and the internal optical path, and a photoelectric converter is provided that alternately receives the light flux passing through each optical path, and the output level and reference level of the photoelectric converter are adjusted. An automatic light amount control device for a light wave ranging device that controls the light amount variable device so that the output level is within a predetermined range based on the output of a comparator that compares the light amount with an electro-optic light control element. 1. An automatic light amount control device characterized in that the control element is provided immediately before the photoelectric converter so as to include both of the optical paths. 2. The automatic light amount adjustment device according to claim 1, wherein the electro-optical light control element is used as a sealing member of the photoelectric converter.