JPS60174969A - Light quantity adjustor for light wave range finder - Google Patents

Abstract

PURPOSE:To enable the adjustment of the quantity of light with a simple construction by making an optical fiber as a part of a reference light optical path and as a part of a light quantity adjustor. CONSTITUTION:The emission end face 10a of the first optical fiber (OF) 11 is set so as to align the optical axis of the incident end face 11a of the second OF11. A rack section 12a formed on a support base 12 of the OF parallel with the optical axis and a rack section 13a formed on a support base 13 of the OF11 parallel with the optical axis are engaged with a pinion 14 and when the pinion 14 is turned in the direction of the arrow R, for instance, the space between the end face 10a of the OF10 and the end face 11a of the OF11 on the optical axis narrows while when it is turned in the direction of the arrow L, the space expands. This permits light to be attenuated according to the distance between the end face 10a of the OF10 and the end face 11a of the OF11 and enter the end face 11a of the OF. Thus, the radiation light attenuated to a desired value is emitted from the emission end provided at a light receiving section passing through the OF11 and incident on a light receiving section to make a reference light thereby enabling the adjusting of light with a simple construction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention divides at least a portion of the optical path from one light emitting element to the light receiving element into two, and allows the ranging light to pass through one optical path and the reference light to enter the light receiving element through the other optical path. The present invention relates to a light wave rangefinder having an optical system.

The above-mentioned light wave distance meter measures distance by detecting the phase difference between the distance measurement light and the reference light, but in order to expand the measurement range of the distance measurement circuit system, a light intensity adjustment device is installed in the reference light optical path. The amount of transmitted light of the light amount adjusting device is adjusted so that it decreases monotonically as the measurement distance increases.

Conventionally, ND filters have been generally used in this light amount adjustment device, but since ND filters are made of film, they have poor heat resistance, and the manufacturing method involves photographic development, which is time-consuming. It had the disadvantage of being inefficient.

The present invention aims to provide a completely new light amount adjustment device that does not use an ND filter, which has many drawbacks as described above, and in which a part of the reference light optical path is constituted by a plurality of optical fibers, and the optical fiber The optical claw is adjusted by changing the distance between the two on the optical axis or by changing the amount of deviation in the direction orthogonal to the optical axis.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic diagram showing an optical system of a light wave distance meter, and FIG. 2 is a partially enlarged view showing an embodiment of a light amount adjusting device according to the present invention provided in a reference light optical path of the light wave distance meter. It is a diagram.

The emitted light from the light transmitting unit 1 is selected by the shutter 2 driven by the shutter drive device 3 as either distance measuring light or reference light. If the distance measuring light is selected now, the distance measuring light passes through the shutter 2 and is reflected by the reflecting surface 6a of the light beam splitter 6.
The light is reflected in the direction of the objective lens 7, passes through the objective lens 7, becomes a parallel beam of light, and is emitted to the outside. This distance measuring light is
It is reflected by the corner cube 8 installed at the distance measurement point, and the reflected light passes through the objective lens 7 again, is reflected by the reflection surface 6b of the light beam splitter 6, and enters the light receiving section 9, where it becomes distance measurement information. In addition, when the reference light is selected, the emitted light from the light transmitting section 1 is reflected by a reflection member 4 such as a mirror provided on the shutter 2, and enters the first optical fiber 10 from the incident end surface 10b. The light passes through the optical fiber 10 and is emitted from its output end face 10a.

Here, as shown in FIG. 2, the output end face 10a of the first optical fiber 10 is installed to face the input end face 11a of the second optical fiber 11 so that their optical axes are the same. Rack section 1 formed parallel to the optical axis on support base 12 of first optical fiber 10
2a and a rack portion 13a, which is also formed parallel to the optical axis on the support base 13 of the second optical fiber 11, mesh with the husband pinion 14, and when the pinion 14 is rotated, for example, in the direction of arrow R, the first rack portion 13a is formed parallel to the optical axis. optical fiber 10
The distance between the output end surface 10a of the second optical fiber 11 and the input end surface 11a of the second optical fiber 11 on the optical axis is narrowed, and the distance widens when rotated in the direction of the arrow.

Therefore, since the light emitted from the output end face 10a of the optical fiber 10 has the property that light decreases as the square of the distance in the atmosphere, the light emitted from the output end face 10a of the first optical fiber 10 and the second optical fiber The light is attenuated in accordance with the distance between it and the incident end surface 11a of the fiber 11, and then enters the incident end surface 11a of the second optical fiber 11.

Note that the attenuation rate at this time can be set to a desired value by rotating the pinion 14.

The amount of rotation of the pinion 14 can be adjusted manually according to the measurement distance, or it can be adjusted automatically by comparing the light intensity of the reference light reaching the light receiving part and the distance measuring light using the well-known foot system. It is possible that

The radiation light thus attenuated to a desired value passes through the second optical fiber 11 and is emitted from its output end face 11b directed toward the light receiving section 9, and enters the light receiving section 9 to become reference light.

FIG. 3 is a partially enlarged view showing another embodiment of the light amount adjusting device according to the present invention, in which the first optical fiber 10
The output end side of the optical fiber 11 is supported by a support stand 15, and the input end side of the second optical fiber 11 is supported by a support stand 16.
The input end face 11a of the optical fiber 11 is placed opposite to the input end face 11a of the optical fiber 11 at a certain interval, but the rack part 15a of the support stand 15 and the rack part 16a of the support stand 16 are
are formed in a direction perpendicular to the optical axis of the optical fiber 10, 11 and mesh with the pinion 17, so when the pinion 17 is rotated clockwise or counterclockwise, the first optical fiber 10 The amount of deviation of the optical axis between the optical fiber 11 and the second optical fiber 11 increases or decreases. In addition, when increasing or decreasing the amount of deviation of the optical axes, the configuration is such that a point where the optical axes coincide, that is, a point where there is no deviation of the optical axes is always included.

Here, as shown in FIG. 4, the optical fiber 18 consists of a core portion 18b and a surrounding cladding portion 18a, and the core portion 18b can only be used within the range of the acceptance angle O calculated by the formula shown below. Unable to receive light.

(1=sin-・6 blue go 1] where θ is the acceptance angle and nl is the optical fiber 18
The refractive index +n2 of the core portion 18b is the refractive index of the cladding portion 186 of the optical fiber 18.

Therefore, the output end face 1 of the first optical fiber 10
The light emitted from 0a enters the input end face 11a of the second optical fiber 11 through the atmosphere, but the light emitted from the second optical fiber 11
Since the core portion of the first optical fiber 11 also has a unique acceptance angle as described above, the first optical fiber 1
0 output end face 10a and second optical fiber 11
The output of the first optical fiber 10 is adjusted by setting the distance in the optical axis direction from the incident end surface 11a to a constant value and adjusting the amount of deviation in the direction orthogonal to the optical axis, which can be increased or decreased by rotating the pinion 17. It becomes possible to adjust the increase/decrease in the amount of light from the end surface 10a to the input end surface 11a of the second optical fiber 11.

The amount of deviation in the direction perpendicular to the optical axis can be adjusted manually according to the measurement distance, as in the embodiment shown in Fig. 2, or automatically using a well-known feedback system. I can do it.

In this way, also in the embodiment shown in FIG. 3, the light emitted from the output end face 10a of the No. The light then passes through the second optical fiber 11, enters the light receiving section 9 from its output end face 11b, and becomes the reference light.

Note that the embodiment shown in FIG. 2 and the embodiment shown in FIG.
a and the entrance end surface 11a of the second optical fiber 11
It is possible to adjust the amount of light at a desired attenuation rate by simultaneously adjusting the distance in the optical axis direction and adjusting the amount of deviation in the direction perpendicular to the optical axis. A similar effect can be obtained by using air as the medium between the fibers 10 and 11, or by using a substance having a certain refractive index as the medium.

Since the present invention is configured as described above, it is not necessary to provide a light amount attenuating member such as a conventionally used ND filter in the reference light optical path, and it is not necessary to provide a light amount attenuating member such as a conventionally used ND filter as a part of the reference light optical path. By using the conventional optical fiber as part of the original reference light optical path and at the same time as part of the light amount adjusting device, the light amount can be adjusted with an extremely simple structure, and the effect is extremely large.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an optical system of a light wave distance meter, and FIG. 2 is a partially enlarged view showing an embodiment of a light amount adjusting device according to the present invention.
FIG. 3 is a partially enlarged view showing another embodiment of the light amount adjusting device according to the present invention, and FIG. 4 is a cross-sectional view of the optical fiber showing the light receiving angle. DESCRIPTION OF SYMBOLS 1... Light transmitting part 9... Light receiving part IO... First optical fiber 10a... Outgoing end face 11 of first optical fiber... Second optical fiber 11a... Second Input end face ha of optical fiber

Claims (1)

[Claims] At least a part of the optical path from the light transmitting section to the light receiving section is divided into two, one optical path is made into a reference light optical path, the other optical path is made into a distance measurement optical path, and further, a part of the reference light optical path is formed. In an optical distance meter configured with optical fibers, a plurality of the above optical fibers are arranged in the reference light optical path,
Depending on the measurement distance, the distance between the output end face of one optical fiber and the input end face of the other optical fiber on the optical axis or the amount of deviation in the direction orthogonal to the optical axis is adjusted to adjust the light intensity of the reference light. A light amount adjustment device for a light wave distance meter, characterized in that it is adjustable.