JPS62178208A - Optical chopper device - Google Patents

Abstract

PURPOSE:To attain simultaneous chopping of many incident light beams only by a simple and small-sized device by forming light reflecting surfaces and light transmitting holes on the side of a hollow rotary drum and projecting light beams from one direction to the side of the drum. CONSTITUTION:The inside of a polygonal drum 1 is hollow and the mirror surfaces 2 and the transmission holes 3 are alternately formed on the side of the drum 1. The drum 1 is directly connected to the shaft of a motor 4 so as to be rotated. Incident light beams and applied from the direction incident on the side of the drum 1, and when both the transmission holes 3 coincide with each other at the observation of the holes from the incident direction, the light beams are transmitted and proceed in the direction of a light receiving element 5. When the incident light beams are applied to the mirror surface 2, the beams are reflected and proceed in the direction of a light receiving element 6. Thereby, the reflecting direction can be changed by changing the position of the incident light beams or changing the position of the transmission holes, so that many incident light beams can be simultaneously chopped.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an optical chopper device that is used in optical power meters, optical spectrum analyzers, and the like, and is useful for optical power measurement, particularly weak light measurement.

Conventional technology Conventionally, as shown in FIG. 3, a disc 7 having a transmission hole 8 is rotated by a motor 4, or as shown in FIG. The light is chopped by vibrating the plate lO.

Furthermore, there is also a method that performs chopping to determine whether Qi transmits or reflects light, rather than chopping to determine whether to transmit or block light. This is as shown in FIG. 5, basically using the configuration shown in FIG. 3, with the surface side of the disk 7 shown in FIG. In addition, the light beams reflected by the mirror surface are guided to the light receiving elements 6, respectively.

Problems to be Solved by the Invention However, in the case of using a rotating disk 7 as shown in FIG. 3 (or FIG. 5), the disk 7 is made larger than the motor 4 in order to secure a path for the light beam. Therefore, miniaturization is difficult. Further, in the case of FIG. 5, the motor 4 and the disc 7 must be tilted with respect to the incident light beam, and the angle adjustment is complicated. When using the tuning fork 9 as shown in FIG. 4, it is simply chopping to transmit or block the light, and it is possible to use a configuration in which one surface of the light shielding plate 10 is mirrored and reflected. Similar to FIG. 5, it is necessary to tilt the light shielding plate 10 with respect to the incident light beam, which is complicated.

In particular, conventionally, it is difficult to realize a configuration in which a plurality of light beams are incident and simultaneously chopped by one optical chopper device.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical chopper device that has a simple configuration, is easy to downsize, and can chop a plurality of incident light beams at the same time.

Means for Solving the Problems The optical chopper device according to the present invention has a cylindrical or polygonal hollow rotating drum, and a side surface of the drum is provided with a light reflecting surface and a light transmitting hole. When the drum rotates and reaches a predetermined angle, the light is transmitted through the light transmission holes that match when viewed from the light projection direction, and when the drum is at another angle, the light is transmitted through the reflective surface. It reflects the light and directs it in a different direction.

A light reflecting surface and a light transmitting hole are provided on the side surface of the hollow rotating drum so that light is projected from one direction toward the side surface of the drum, so that the drum rotates and reaches a certain rotation angle. When viewed from the light projection direction, the light transmission holes coincide. Therefore, when the drum rotates to this angle, the light projected onto the side of the drum will pass through in that direction.

On the other hand, when the drum rotates to a different angle, the light is reflected in a certain direction by the reflective surface. Therefore,
When the drum rotates to that angle, the light projected onto the side of the drum is redirected and directed in a different direction.

In this way, as the drum rotates, the light projected from direction (2) is chopped in at least two directions.

If the position of the projected light is changed, the light beam at that position undergoes similar transmission and reflection, and since the direction of reflection is different from that of the light beam at other positions, it is possible to chop a large number of incident light beams at the same time.

Embodiment In FIG. 1, a polygonal drum 1 is hollow inside, and mirror surfaces 2 and transparent holes 3 are alternately provided on its side surfaces. This drum l is directly connected to the shaft of a motor 4 and is rotated by this motor 4. The incident light beam is applied from the direction of incidence toward the side surface of the drum l, and the transmission hole 3 when viewed from the direction of incidence.
When the incident light beams match, the light beam is transmitted and directed toward the light receiving element 5, and when the incident light beam hits the mirror surface 2, it is reflected and directed toward the light receiving element 6.

That is, when the drum 1 is at a rotation angle as shown in FIG. 2(A), the light beam I passes through the two coincident transmission holes 2, but the light beam 1 is then rotated a little and is at the rotation angle shown in FIG. 2(B).
At a rotation angle such as , the light beam I is reflected by the mirror surface 2 and goes in the reflection direction.

In FIG. 1, for convenience, the transmission hole 3 is depicted as having an edge around it, but such an edge causes unnecessary reflection, so it is desirable to remove it. Furthermore, it is actually preferable that the areas of the mirror surface 2 and the transmission hole 3 are approximately the same in order to equalize the amount of transmitted light and the amount of reflected light.

Changing the position of the light beam changes the direction of reflection, and also changes whether it is transmitted or reflected at a certain rotation angle. That is, when looking at the beams Ro and C which are incident at a different position from the beam A, they are reflected at a rotation angle as shown in FIG. 2(A) and transmitted at a rotation angle as shown in FIG. 2(B).

In this way, by changing the position of the incident light beam or by changing the position of the transmission hole, the reflection direction can be changed, and a large number of incident light beams can be chopped simultaneously.

Further, since the motor 4 occupies a position that is not related to the path of the light beam, the size of the motor 4 is not limited, and the size of the motor 4 can be reduced.

Since it can chop in two directions, two light receiving elements 5 are used.
．． 6 can be used to realize a photodetector that converts optical power into an electrical signal without wasting it, and is suitable for measuring small amounts of light. In this case, the detected optical signal is alternating current, and a low-drift, low-noise AC amplifier can be used as the electrical circuit, and optical power is not wasted, so a highly sensitive and highly accurate optical measuring instrument is constructed. can.

Note that the light-receiving element 5 in the transmission direction and the light-receiving element 6 in the reflection direction may be made of elements having different wavelength sensitivity characteristics, such as Ge or S+. Then, by measuring the difference between the output signals, it can be used as a light detection section of an optical wavelength meter.

In addition, although the drum l is formed into a polygon in the above example,
It may be cylindrical. In the case of a cylindrical shape, the mirror surface 2 will be curved, so the beam of reflected light will spread somewhat, but when the light beam hits the mirror surface 2 and is reflected, the direction of the reflected light will change depending on the rotation of the drum 1. It has the advantage that it does not fluctuate, and it also has the advantage that it is easy to manufacture. On the other hand, in the case of a polygon, when the light beam hits the mirror surface 2 and is reflected, the direction of the reflected light swings due to the rotation of the drum 1, but the beam of one reflected light does not spread.

Effects of the Invention According to the optical chopper device of the present invention, the structure is simple and miniaturization is easy. Furthermore, simultaneous chopping of multiple incident light beams is also possible with one optical chopper device. Further, the optical power can be chopped and detected without waste, and it can also be used as a mechanical optical switch.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of one embodiment of the present invention, and FIG. 2 (A
) and (B) are schematic diagrams for explaining the operation, FIGS. 3 and 4 are schematic perspective views of the conventional example, and FIG. 5 is a schematic sectional view of another conventional example.

Claims (1)

[Claims] (1) It has a hollow rotating drum, a light reflecting surface and a light transmitting hole are provided on the side surface of the drum, and light is projected from one direction toward the side surface of the drum, and the drum rotates at a predetermined angle. An optical chopper device that transmits light through a matching light transmission hole when viewed from the light projection direction, and reflects the light from a reflective surface and directs it in another direction when the angle is different.