JPH01141359A - Optical deflection detecting device - Google Patents

Abstract

PURPOSE:To obtain high sensitivity by a simple constitution by reflecting an emitted light from a semiconductor laser by a specular surface formed integrally in an actuator movable part and converting it to a return light to the semiconductor laser itself. CONSTITUTION:The front output light of a semiconductor laser 6 forms a focus in the vicinity of the reflecting mirror M of an actuator movable part 1 by optical system 8, 9. When an acceleration input is applied, and the actuator movable part 1 is deflected, the quantity of a return light to the semiconductor laser 6 is varied, and the output of the semiconductor laser 6 is varied greatly by a self-coupling effect. This output of the semiconductor laser 6 is detected by a photodetector 7, and fed back to the torquer coil 2 of the actuator movable part through a servo-amplifier. By detecting this feedback current, the acceleration input can be known.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical deviation detection device using a semiconductor laser, and particularly to an optical deviation detection device that can be used in a high-precision servo accelerometer or the like.

(Prior Art) A conventional optical deviation detection device will be described with reference to FIGS. 6 and 7.

FIG. 6 is a sectional view of a conventional optical deviation detection device, and FIG. 7 is a diagram showing mainly the optical system of the device.

The actuator movable part includes a rod-shaped pendulum 601, hinge parts 602, 602 that support this on a base, and a rod-shaped pendulum 601.
It consists of a torquer coil 603 provided in the.

Magnetoro 04.605 is fixed to the base so as to sandwich the torquer coil 603.

A light emitting element 606 and light receiving elements 607a and 607b of 2111i1 are fixed to a base at positions sandwiching the rod-shaped pendulum 601.

When acceleration is applied to the actuator movable part, the hinge part 6
A rotational movement occurs in the rod-shaped pendulum 601, which is integrated with the torquer coil 6°3, with the rotation center at 02.

As a result, the rod-shaped pendulum 601 blocks a part of the center of the light emitted from the light emitting element 606, and the two light receiving elements 607a and 6
The light emitted from the light emitting element 606 is moved upward or downward from the position shown in FIG.

As a result, the amount of light received by the two light receiving elements 607a and 607b changes differentially.

The electric signals photoelectrically converted by the light receiving elements 607a and 607b are current amplified and fed back negatively to the torquer coil 603. This feedback current causes the torquer coil 60
The torque generated between the actuator 3 and the magnets 604 and 605 acts to return the actuator movable part to the state before the acceleration input, thereby forming an equilibrium state.

Therefore, by measuring this negative feedback current, it is possible to know the acceleration applied to the actuator movable part, and the optical deviation detection device can be used for acceleration detection.

(Problems to be Solved by the Invention) As described above, in the conventional optical deviation detection device, the rod-shaped pendulum 601 blocks a part of the light emitted from the light emitting element 606, and the remaining light passing through the two Light receiving element 607a, 60
It is configured to convert the deviation into an electrical signal by differentially receiving light at 7b.

At this time, the passing light is diffracted at the side surface of the rod-shaped pendulum 601 as a shield, and the influence of the side surface may become unclear due to the light passing around to the back surface of the rod-shaped pendulum 601 as a shield.

Further, even if differential detection is used, the change in the amount of electricity between the light receiving elements 607a and 607b corresponds to the change in the amount of light corresponding to the deflection of the rod-shaped pendulum 601, so the sensitivity is not very high.

Moreover, it is necessary to bond and integrate the torquer coil 603 with the rod-shaped pendulum 601 due to its structure, but it is not easy to ensure the accuracy of the mounting angle of the torquer coil 603.

Furthermore, the rod-shaped pendulum 601 and the hinge part 602 must be assembled by adhesive fixing, and there is also a manufacturing problem in that the number of parts is large and assembly is difficult.

A first object of the present invention is to provide a new type of optical deviation detection device that is easy to assemble with a small number of parts.

A second object of the present invention is to provide a new type of optical deviation detection device that can perform detection with even higher sensitivity.

(Means for Solving the Problems) In order to achieve the first object, an optical deviation detection device according to the present invention is provided such that it is supported around a fulcrum part as a center of rotation and is deflected in a magnetic field by an external force. an actuator having a movable coil having a movable coil and a movable part having an optical reflection surface; a semiconductor laser; and an actuator that projects emitted light from the semiconductor laser toward the optical reflection surface and reflects reflected light that changes depending on the amount of deviation of the optical reflection surface. It is composed of an optical system that makes the light incident on the semiconductor, a light receiving element that detects a change in the semiconductor laser output due to the self-coupling effect of the semiconductor laser, and a servo amplifier that couples the output of the light receiving element to the actuator in negative feedback.

The fulcrum part is formed as a circular notch fulcrum in the base of quartz glass, the optical reflection surface is formed by thin film coating on a quartz glass plate, and the movable coil fixed to the quartz glass plate has a quartz glass plate. Current can be supplied via wiring formed with a thin film coating thereon.

In order to achieve the second object, the optical deviation detection device according to the present invention includes a pair of movable coils that are supported around a fulcrum part as a center of rotation and are provided to be displaced within a magnetic field by an external force, and a pair of optical reflectors. an actuator having a movable part with a surface; a pair of semiconductor lasers; and a pair of semiconductor lasers, each of which projects the emitted light from each of the semiconductor lasers toward the corresponding optical reflection surface, and receives reflected light that changes depending on the amount of deviation of the optical reflection surface. a pair of optical systems that make the light incident on each semiconductor; a pair of light receiving elements that detect changes in semiconductor laser output due to the self-coupling effect of each of the pair of semiconductor lasers; It consists of a servo amplifier.

(Example) The present invention will be described in more detail below with reference to the drawings and the like.

FIG. 1 is a block diagram showing the basic configuration of an optical deviation detection device according to the present invention, and FIG. 2 is a principle diagram for explaining the operation of the device.

FIG. 3 is a graph showing the relationship between the displacement of the mirror obtained when the mirror is displaced and the output light of the semiconductor laser in the optical system of FIG. 2.

As shown in FIG. 2, in the device according to the invention:
The light emitted from the semiconductor laser (LD) 6 is focused by a focusing optical system consisting of two lens groups 8.9, and a reflecting mirror (M) is installed near the beam waist.

This reflecting mirror (M) is supported so as to be movable in the optical axis direction (X direction).

The back-emitted light from the semiconductor laser (LD) 6 is sent to the light receiving element (
PD)? Detected in

While moving the reflecting mirror (M) in the X direction, the light receiving element (
PD)? The output of the semiconductor laser (LD) 6 detected in FIG. 3 is shown in FIG.

The graph in Figure 3 shows that the reflection iff (M) is 8°9 for the lens group.
JUST FOCUS
), the amount of reflected light is maximum, and the semiconductor laser (
This shows that the amount of return light that returns and couples to LD) 6 itself is at a maximum.

At this time, the reflecting mirror (
M) acts as a reflective surface of the external cavity, producing an effect similar to the increase in the forward reflectance of the semiconductor laser chip,
The luminous output is significantly increased. This effect is called the self-binding effect.

Furthermore, from the graph of FIG. 3, it can be seen that the rate of change in the optical output with respect to mirror displacement is maximum when the reflecting mirror (M) is near the position xl.

FIG. 1 is a block diagram showing a somewhat more specific configuration of an optical deviation detection device according to the present invention that utilizes this self-coupling effect.

The actuator movable part is constructed by forming a reflecting mirror (M) on a part of a plate 1 having a hinge part 3, and integrating a permanent magnet 5 and an associated torquer coil 2.

In the actuator movable part, in response to acceleration input, the reflector (M) and torquer coil 2 rotate around the hinge part.
is a deflecting structure.

The torquer coil 2 is arranged so as to cross the lines of magnetic force of a permanent magnet 5 attached to a base (not shown).

The forward output light of the semiconductor laser (LD) 6 is transmitted through the optical system 8.9.
The beam is arranged so as to be focused near the reflecting mirror (M) of the actuator movable part.

Now, with no acceleration input, the positional relationship between the output of the semiconductor laser (LD) 6 and the reflection ill (M) is set as shown in FIG. 3 x1.

When an acceleration input is applied and the actuator movable part 1 is deflected, the amount of light returned to the semiconductor laser (LD) 6 changes,
The output of the semiconductor laser (LD) 6 changes greatly due to the self-coupling effect. Is the output of this semiconductor laser (LD) 6 a photodetector (PD)? is detected and fed to the torquer coil 2 of the actuator movable part via the illustrated servo amplifier.

A torquer consisting of a torquer coil 2 and a permanent magnet 5
generates a force in the direction of pushing the actuator movable part back to the state before it was deflected.

In this force equilibrium state, the acceleration input is proportional to the feedback current, so the acceleration input can be known by detecting this analog output.

In this way, a novel and highly sensitive optical deviation detection device utilizing the self-coupling effect of a semiconductor laser can be obtained.

FIG. 4 is a diagram showing a more specific embodiment of the optical deviation detecting device for a servo acceleration pointer, and FIG. 5 is a side view thereof.

Torque coils 2 are concentrically fixed to both sides of an actuator movable part 1 made of a quartz glass plate.

In order to function as a fulcrum near the attachment point of the actuator movable portion 1 to the base, a fulcrum portion 3 is provided which is locally thinned by circular arc notches on both sides when viewed from the plate thickness direction.

The central part of both sides of the actuator movable part l has a mirror surface part 4 (fifth
(see figure) is provided.

The wire end of the torquer coil 2 is connected to the actuator movable part 1.
A coil electrode portion 2a is coated with a conductive thin film on a portion including the circular arc notch fulcrum portion 3 on both sides of the coil electrode portion 2a.

2b.

A set of permanent magnets 5 are fixed to the base, and the torquer coils 2 are arranged to cross the magnetic flux when the actuator movable part 1 is deflected about the circular arc notch fulcrum part 3 as a fulcrum.

Semiconductor laser 6, light receiving element 7. The condensing optics consisting of lenses 8, 9 are each mounted as an assembly in a symmetrical position with respect to the actuator movable part 1.

The laser beam emitted from the semiconductor laser 6 passes through the lens 8.9.
When the mirror surface part 4 of the actuator movable part 1 is located at the position where the light is focused by the condensing optical system consisting of the following, and the deflection of the actuator movable part 1 is zero, the optical output change with respect to the mirror displacement shown in FIG. 3 becomes maximum. At a position corresponding to position Xl, a semiconductor laser 6.degree. light receiving element 7. Adjust and fix the assembly of lenses 8.9 as condensing optics.

The stopper 10 is a stopper that prevents excessive displacement of the actuator movable portion 1 fixed to the base.

(Effects of the Invention) As explained in detail above, the optical deviation detection device according to the present invention uses a semiconductor laser as a light emitting element, and uses a mirror surface integrated with the movable part of the actuator to emit light emitted from the semiconductor laser. The structure is configured so that the light is reflected and returned to the semiconductor laser itself, and when the movable part of the actuator is deflected around its fulcrum part by an external force as the rotation center, the amount of returned light changes, and the output of the semiconductor laser is increased due to the self-coupling effect of the semiconductor laser. A method is used to detect changes.

Therefore, compared to conventional optical deviation detection devices, the configuration is simpler and high sensitivity detection is possible.

In addition, the actuator movable part has a circular arc notch fulcrum in a part of the quartz glass plate, and a mirror surface and an electrode are formed on the quartz glass plate with a thin film coating.
This reduces the number of parts and makes it lighter.

Furthermore, by providing coils and reflecting mirrors on both sides of the movable part and utilizing the differential effects of the pair of reflective surfaces provided on the movable part, it is possible to provide a device with improved layer sensitivity. .

The device according to the invention is capable of detecting small deviations and is particularly applicable to high-precision servo acceleration needles.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of an optical deviation detection device according to the present invention. FIG. 2 is a diagram showing the principle of an optical system for explaining the operation of the optical deviation detection device according to the present invention. FIG. 3 is a graph showing the relationship between mirror displacement and light output obtained when the mirror is displaced in the optical system of FIG. 2. FIG. 4 shows a basic configuration example of an optical deviation detection device for a servo acceleration pointer, which is an embodiment of the optical deviation detection device according to the present invention. FIG. 5 is a side cross-sectional view of the servo acceleration deflection detecting device shown in FIG. 4. FIG. FIG. 6 is a sectional view of a conventional optical deviation detection device. FIG. 7 is a plan sectional view of a portion of the optical deviation detection device shown in FIG. 6. l... Actuator movable part 2... Torque coil 3... Arc notch fulcrum 4... Mirror surface part 5... Permanent magnet 6... Semiconductor laser (LD) 7... Light receiving element ( P D) 8.9...Lens

Claims (3)

[Claims] (1) An actuator having a movable coil supported around a fulcrum part as a center of rotation and provided to be deflected in a magnetic field by an external force and a movable part having an optical reflection surface; a semiconductor laser; an optical system that projects reflected light toward an optical reflective surface and that changes depending on the amount of deviation of the optical reflective surface and makes it incident on the semiconductor; a light receiving element that detects a change in semiconductor laser output due to a self-coupling effect of the semiconductor laser; An optical deviation detection device comprising a servo amplifier that couples the output of a light receiving element to the actuator in negative feedback. (2) The fulcrum part is formed as a circular arc notch fulcrum at the base of the quartz glass, the optical reflective surface is formed by thin film coating on the quartz glass plate, and the movable coil fixed to the quartz glass plate is made of quartz glass. 2. The optical deviation detection device according to claim 1, wherein a current is supplied through wiring formed by thin film coating on a glass plate. (3) an actuator having a movable part having a pair of movable coils supported around a fulcrum part as a center of rotation and deflected in a magnetic field by an external force and a pair of optical reflective surfaces; a pair of semiconductor lasers; a pair of optical systems that project emitted light from semiconductor lasers toward the corresponding optical reflective surfaces and make reflected light that varies depending on the amount of deviation of the optical reflective surfaces enter each of the semiconductors; An optical deviation detection device comprising a pair of light receiving elements for detecting a change in semiconductor laser output due to a self-coupling effect, and a pair of servo amplifiers for negative feedback coupling of the outputs of each of the light receiving elements to the actuator.