JPH0368888A - Optical distance meter - Google Patents

Abstract

PURPOSE:To simplify a constitutional part and to reduce the attenuation of the quantity of distance measuring light due to reflection by providing a diaphragm having a slit and capable of controlling the transmission quantity of distance measuring light according to a rotary position. CONSTITUTION:The contour of a diaphragm 14 consists of a plurality of circular arcs having different radii centering around the rotary shaft of a stepping motor 15 and has a slit 14a whose width is changed in its longitudinal direction. When reflected light (distance measuring light) is perfectly shielded, only reference light having an angle theta with respect to an avalanche photodiode 5 passes through the slit 14a to be incident to the avalanche photodiode 5. At this time, the incident quantity of reference light can be adjusted to an arbitrary value by finely rotating the diaphragm 14 by the stepping motor 15. In this case, since the reflection of distance measuring light due to vapor deposition is only once, the attenuation of the quantity of light due to reflection is reduced and loss is also reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention projects light onto a reflector, and the reflected light 1d
A light wave distance meter that measures the WP distance from to a reflector, especially -
This relates to a visual-type optical distance meter.

(Prior art) Fig. 4 is a diagram showing the main configuration of a light wave length 1111; 4f of a conventional single-lens system.
ED, 2 is a lens for projecting collimated (parallel) light onto the reflector 3, 4 is a distance measuring light for measuring the distance to the reflector 3 using the light from LED 1, and LED l. The prism 5 branches into a reference light indicating the luminous intensity, and an avalanche photodiode 5 receives the ranging light and the reference light, and the distance from the output of the avalanche photodiode 5 to the reflector 3 is measured. Reference numeral 6 denotes a chopper that switches between the S path light and the reference light and guides the same to the prism 4, and is rotationally driven by a stepping motor 7. Reference numeral 8 denotes a density filter which adjusts the amount of distance measuring light reflected by the reflector 3 and the reference light from the prism 4 and guides it to the avalanche photodiode 7, which is rotationally driven by the stepping motor 9. 10.11 is a condenser lens and an interference filter arranged in the optical path of the reference light, and 12.13 is an optical fiber whose one end face is fixed to the LED 1 and the avalanche photodiode 5.

The light emitted from the LED 1 passes through the optical fiber 12,
The rotation of the chopper 6 switches between the distance measuring light and the reference light. Of these, the distance measuring light is reflected by the aluminum vapor-deposited portion of the prism 4, and is guided to the lens 2 to become collimated light. This collimated ranging light is
It is reflected by the reflector 3 and passes through the lens 2 again, where it is focused and guided to the prism 4. After being reflected by the evaporated portion of the prism 4, the light m is adjusted by the density filter 8 and enters the avalanche photodiode 5 through the optical fiber 13.

- On the other hand, the reference light is condensed by the condenser lens 10, passes through the vapor-free RR of the prism 4, is totally reflected on the inner surface of the prism 4, and is guided to the interference filter 11 and the density filter 8. The amount of light is adjusted by this density filter 8, and the light is transmitted from the optical fiber 13 to the avalanche photodiode 5.
is incident on the

[Problem to be solved by the invention]

A conventional single-lens optical distance meter is configured as described above, and includes a chopper that switches between the distance measurement light and the reference light, and a light 1t3.
Since a concentration filter for Ia is provided separately, a stepping motor for rotational drive is also required, and a condenser lens is also required to narrow down the reference light, making the configuration complicated due to the large number of components. There was a problem.

In addition, since optical fibers are used for the light emitting part and the light receiving part, the efficiency is low, and the prism requires two evaporated surfaces.
Since there are two reflections on the vapor deposition surface, there is a problem that the amount of light is attenuated and the loss is large.

The present invention has been made in view of these problems, and aims to provide a light wave distance meter that has an N-unit configuration, is highly efficient, and has low loss.

[T stage for solving the three problems] The light wave distance meter of the present invention includes a light emitting element, a light receiving element that receives distance measuring light emitted from the light emitting element and reflected by a reflector, and a reference light indicating the luminous intensity of the light emitting element. A single-lens optical distance meter that measures the distance from the output of the light-receiving element to the reflector, which has a slit whose width changes depending on the rotational position in the optical path of the reference light, and a distance measuring light. A diaphragm plate is provided whose transmission amount can be controlled by the rotational position, and the rotation of this diaphragm plate controls the switching between the distance measuring light and the reference light incident on the light receiving element, and also controls the light amount of each incident light. and the above light emitting element uses an LED,
An avalanche fetish diode is used as a light receiving element.

[Effect]

The optical distance meter of the present invention is provided with a diaphragm plate that has a slit whose width changes depending on the rotational position in the optical path of the reference light, and can control the amount of transmission of the distance measuring light depending on the rotational position. This diaphragm plate switches between the distance measuring light and the reference light and adjusts the input of each light onto the light receiving element.

〔Example〕

FIG. 1 is a block diagram showing the main parts of a single-lens optical distance meter according to an embodiment of the present invention, and the same reference numerals as in FIG. 4 indicate the same components. In the figure, 1 is an LED which is a light emitting element, 2 is a condensing lens, 3 is a reflector, and 4 is 1
The prism has a vapor-deposited portion only on its surface, and 5 is an avalanche photodiode as a light receiving element, which receives the ranging light emitted from the LEDI and reflected by the reflector 3 and the reference light indicating the luminous intensity of the LED 1. Reference numeral 14 denotes an aperture plate rotationally driven by a stepping motor 15, which has a slit whose width changes depending on the rotational position in the optical path of the reference light, and allows the amount of distance measurement light transmitted through the plate to be controlled by the rotational position. The rotation C of the diaphragm plate 14 controls the switching between the ranging light and the reference light incident on the avalanche photodiode 5, and also controls the amount of each incident light.

A part of the light emitted from the LED 1 becomes distance measuring light and is collimated by the lens 2, for example, the distance ail (m
) Light is projected from a reflector 3C placed at a remote location. The distance measuring light reflected by this reflector 3 enters the lens 2 again, only half of the incident light is reflected by the vapor deposited surface of the prism 4, and after adjusting the light amount by the diaphragm plate 14, the avalanche photodiode 5 The light is focused on.

Also, of the light emitted from LED 1, 90% of the light emitted from LED 1 is
Only the light with the angle of °-θ becomes the reference light, and the aperture plate 1
It passes through the slit provided in 4. The reference light whose light intensity is adjusted by this slit enters the avalanche photodiode 5 at an angle of θ with respect to the avalanche photodiode 5.

The distance measuring light and the reference light incident on the avalanche diode 5 are converted into electric signals according to the amount of each incident light. A distance ail (m) is measured.

Next, the function of the aperture plate 14 mentioned above will be explained in detail. FIG. 2 shows the shape of the aperture plate 14.

The outline of this diaphragm plate 14 consists of a plurality of circular arcs with different radii centered around the rotating shaft of the stepping motor 15, and the slit 14a whose width changes in the longitudinal direction mentioned above. have. The circle gAAC has a constant radius R8, but the point C
, D, and E is not constant, but continuously decreases from radius R6 to Ri (Ro>R1). The slit 14a is provided within the arc connecting points B and D.

FIG. 3 shows a typical positional relationship between the rotational position of the aperture plate 14 controlled by the stepping motor 15 and the position of the avalanche photodiode 5. Figure 3(a)
3(b) shows a state in which the avalanche photodiode 5 receives 100% of the reflected light from the reflector 3 without being affected by the aperture plate 14. FIG. Figure 3 (
C) shows a state where it is completely hidden by the avalanche photodiode 5 or the diaphragm plate 14 and does not receive any reflected light from the reflector 3. When the reflected light (?l distance optical path light) in FIG. 3(c) is completely blocked, only the reference light having an angle of θ with respect to the avalanche photodiode 5 passes through the slit 14a. and enters the avalanche photodiode 5. At this time, the amount of incident reference light can be adjusted to an arbitrary value by slightly rotating the diaphragm plate 14 with the stepping motor 15.

In other words, Figs. 3(a) and 3(b) show the state during distance measurement;
Figure (C) shows the state at the time of reference.

In this way, by reversing each of the states shown in FIGS. 3(a), (b), and (c), it is possible to switch between the ranging light and the reference light and adjust the amount of each light.

Therefore, there is no need to provide a separate imager or density filter to switch between the distance measurement light and reference light and adjust the light intensity, only one stepping motor is required, and there is no need for a condenser lens to narrow down the reference light. This reduces the number of components and simplifies the configuration. Furthermore, since the prism only needs to have one vapor deposition surface, and the distance measuring light is reflected only once during vapor deposition, there is less attenuation of the amount of light due to reflection and loss is reduced. Furthermore, since no optical fiber is required, efficiency is improved.

〔Effect of the invention〕

As described above, according to the present invention, a diaphragm plate is provided which has a slit whose age changes depending on the rotational position in the optical path of the reference light and which can control the amount of transmission of the ranging light by the rotational position. Switching between the distance measuring light and the reference light and controlling the amount of each light incident on the light receiving element are performed by using the 3-axis switch, which simplifies the configuration with fewer components and reduces light loss due to less attenuation of the distance measuring light due to reflection. This has the effect of increasing efficiency, and since no optical fiber is required, the efficiency is high.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of the present invention, Fig. 2 is a plan view showing the shape of the diaphragm plate in Fig. 1, and Figs. 3(a) and (b).
) and (c) are explanatory diagrams showing the positional relationship between the diaphragm plate and the avalanche photodiode in FIG. 1, and FIG. 4 is a configuration diagram showing a conventional optical distance meter. 1... LED (light emitting element) 2... Lens 3... Reflector 4... Prism t4... Diaphragm plate 14a... ... Slit 15 ... Stepping motor

Claims (4)

[Claims] (1) A light-emitting element, a light-receiving element that receives ranging light emitted from the light-emitting element and reflected by a reflector, and a reference light indicating the luminous intensity of the light-emitting element, and the distance from the output of the light-receiving element to the reflector. In a single-lens optical distance meter that measures
A diaphragm plate is provided which has a slit whose width changes depending on the rotational position in the optical path of the reference light and can control the amount of distance measurement light transmitted by the rotational position, and the distance measurement beam is incident on the light receiving element by rotation of the diaphragm plate. A light wave distance meter characterized by controlling switching between a light and a reference light and controlling the amount of each incident light. (2) The optical distance meter according to claim 1, wherein the reference light passes through a slit in the aperture plate and is directly incident on the light receiving element from the light emitting element. (3) The light wave distance meter according to claim 1 or 2, wherein the light emitting element is an LED. (4) The optical distance meter according to any one of claims 1 to 3, wherein the light receiving element is an avalanche photodiode.