JPS6313168B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical device for obtaining a parallel scanning light beam from an incident light beam.

For example, when measuring the external shape of an object optically,
A parallel beam of light is required to scan a certain range of space.

FIG. 1 is a diagram showing an example of an outline of measuring the outer shape of an object, in which 1 is a laser light source, 2 is a deflector, 3 is a collimator lens, and S is an object to be measured.

This external shape measurement method involves irradiating a laser beam emitted from a laser light source 1 onto a vibrating or rotating deflector 2, and converting the beam reflected from the deflector 2 into a parallel beam by a collimator lens 3. do.
Since the object to be measured S is located in the space scanned by this parallel light beam, if the shadow part caused by the parallel light beam is detected by some means, the outer shape of the object to be measured S can be determined without touching the object S. can be measured.

In this method of measuring the external shape, it is necessary to form a sharp parallel light beam in order to improve the measurement accuracy, which requires an expensive collimator lens 3 and also requires the deflector 2 to be placed on the black spot of the collimator lens 3. The design must ensure that the reflective surface is accurately located.

Therefore, there is a problem that the optical device becomes expensive, and furthermore, when the deflection angle of the light beam reflected from the deflector 2 becomes large, it becomes a parallel light beam whose parallelism is broken due to the aberration of the collimator lens 3. There are drawbacks.

The present invention relates to a light source that solves these problems, and provides an optical device that can obtain a parallel scanning beam without using a collimator lens.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A device for obtaining a parallel light beam from an incident light beam according to the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic diagram showing an embodiment of this invention.
10 is a U-shaped tuning fork, 11 and 12 are the tuning forks 10
The first and second movable reflecting mirrors are attached to the vibrating ends of the oscillator, and reference numeral 13 is a fixed fixed reflecting mirror. It is preferable that the tuning fork 10 is provided with a driving coil 14 and a vibration detection coil 15 to control the vibration of the tuning fork 10.

In such a device, a light beam from a light source with higher convergence than point P, such as a laser light source, is incident on the first movable reflector 11, a fixed reflector 13 is disposed in the path of the reflected light, and then the second movable reflector 13 is placed in the path of the reflected light. movable reflector 12
When configured to irradiate the light beam, the incident light beam is emitted via an optical path A shown by a solid line.

Now, an alternating current is applied to the coil 14, and the tuning fork 1
When an electromagnetic force is applied to the tuning fork 10, the tuning fork 10 vibrates according to its natural frequency, and the first and second movable reflecting mirrors 1
Reflection surfaces 1 and 12 change. That is, when the tuning fork 10 is deflected as shown by the dotted line due to vibration, the reflecting surfaces of the first and second movable reflecting mirrors 11 and 12 both change outward, as shown by the dashed line. When it deviates, the first and second movable reflecting mirrors 1
Both reflective surfaces 1 and 12 change inward.

Therefore, when the first movable reflecting mirror 11 changes the reflection surface by Δθ, the light beam incident from the point P is reflected at a reflection angle larger by 2Δθ than the optical path A, and continues along the optical path B as shown by the dotted line. 2nd along
is incident on the movable reflecting mirror 12, but here -
Since the direction of the reflecting surface has changed by Δθ, the second
The light flux emitted from the movable reflecting mirror 12 is, after all,
It becomes a parallel light beam in the same direction as the previous optical path A.

Furthermore, even if the angle of the reflecting surface of the first movable reflector 11 changes by -Δθ, the second movable reflector 1
2 changes the angle of the reflecting surface by Δθ, so
Although the traveling path of the light flux incident from point P changes at the first and second movable reflecting mirrors 11 and 12, it ultimately becomes a parallel light flux and exits.

The parallelism of the parallel light beam is determined by the first and second movable reflecting mirrors 1
Accuracy is higher when the deviations of 1 and 12 are the same and in opposite phases, but in general, in a U-shaped tuning fork 10 with a high Q value, the two fork parts have sufficient accuracy when vibrating. Since they vibrate in opposite phases and with the same amplitude, it is easy to stabilize the voltage by controlling the amplitude of the alternating current flowing through the drive coil 14 so that the voltage generated in the vibration detection coil 15 is constant. A vibration state is obtained, and parallel light beams with good parallelism are easily generated.

FIG. 3 shows an outline of another embodiment of the present invention, in which 20A and 20B are rotary drive bodies;
Reference numerals 1 and 22 designate first and second rotating polygon mirrors that are connected to the rotary drive bodies 20A and 20B, for example, by gear coupling, and 23 is a fixed reflecting mirror.

In this embodiment, as in the embodiment shown in FIG. After being reflected by the mirror 22, the light beam is configured to be incident on the second rotating polygon mirror 22 again.

Then, the positions of the mirror surfaces of the first and second fixed rotation polygon mirrors 21 and 22 are synchronized and controlled so that they rotate in opposite directions.

Therefore, at a certain point, the light beam incident from point P travels along the solid line optical path A and reaches the second rotating polygon mirror 2.
From this point on, the first and second rotating polygon mirrors 21 and 22 have a rotation angle of Δθ or −Δθ.
When rotated in opposite directions, the dashed line,
Then, the light travels through different optical paths B and C as shown by two-dot chain lines and enters the second rotating polygon mirror 22.

However, as explained above in the case of FIG. 2, the light beam reflected by the second rotating polygon mirror 22 is
Since they are all reflected in the same direction, the scanning light beam obtained by the rotation of the rotary drives 20A and 20B forms a parallel light beam L.

In this embodiment, one scanning light beam is obtained by one reflecting surface of the rotating polygon mirror, so n scanning light beams are outputted as parallel light beams L for each rotation of the n-sided rotating polygon mirror.

Although a case has been described in which the first and second rotating polygon mirrors 21 and 22 are driven by gear coupling, the rotation of the first and second rotating polygon mirrors 21 and 22 is controlled by a synchronized motor, respectively. In this case, a servo mechanism can be added based on a signal obtained by optically detecting the parallelism of the parallel light beam.

As explained above, the device for obtaining a parallel scanning light beam from an incident light beam according to the present invention has the advantage that the optical device is inexpensive because there is no need to use an expensive collimator lens to convert the light beam into a parallel light beam. This has the effect that by improving only the precision of the reflecting mirror, a parallel light beam that can scan a wide range can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a method for measuring the external shape of an object to be measured, FIG. 2 is a schematic explanatory diagram of a device showing one embodiment of the present invention, and FIG. 3 is a schematic diagram of a device showing another embodiment of the present invention. FIG. In the figure, 10 is a tuning fork, 11 is a first movable reflector,
12 is a second movable reflecting mirror, 13 is a fixed reflecting mirror, 1
4 and 15 are coils, 20A and 20B are rotary drive bodies, and 21 and 22 are first and second rotating polygon mirrors.

Claims (1)

[Scope of Claims] 1. A first movable reflecting mirror disposed at a position to receive an incident light beam with good directionality and supported so as to be able to change the reflection angle of the incident light beam; reflection of the first movable reflecting mirror; a fixed reflecting mirror arranged at a position to receive the light beam; a second movable reflecting mirror arranged at a position to further reflect the reflected light beam from the fixed reflecting mirror and supported so as to be able to change the reflection angle of the reflected light beam; ; a driving device that drives the first and second movable mirrors so that the reflection angles of the first and second movable mirrors are deflected in opposite phases to each other; A device that obtains a parallel scanning beam. 2. The incidence according to claim 1, wherein the drive device is a U-shaped tuning fork, and the first and second movable reflectors are attached to the respective free ends of the U-shaped tuning fork. A device that obtains a parallel scanning beam from a beam of light. 3. The first and second movable reflecting mirrors are each rotary polygon mirrors, and are provided with a synchronous rotation mechanism that rotates in opposite phases to each other, from the incident light beam to the parallel A device that obtains a scanning beam of light.