JPH0244258Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a laser beam focusing device, and in particular to an optical axis and The present invention relates to a laser beam focusing device having focus error detection means.

Conventionally, this type of laser beam focusing device has been used, for example, in a laser fusion system, and as shown in FIG.
a reflecting mirror 2, a condensing lens 3, a first automatic mirror gimbal 4 for adjusting the angle of the reflecting mirror, and a second automatic mirror gimbal 4 for adjusting the angle of the reflecting mirror.
an automatic mirror gimbal 5, a lens driving device 6 for adjusting the focus of the condensing lens 3, a vacuum chamber 7 with a target 9 installed therein, a vacuum shield glass 8, and a laser beam with a diameter of 0.1 to 1.0.
It is comprised of an optical axis and focus error detection means 10 for accurately focusing light on the center of a spherical target 9 of about mm size.

The conventional optical axis and focus error detection means, for example, as shown in FIG. , automatic mirror gimbal drive circuits 17 and 18 that provide correction signals to the automatic mirror gimbal, and a drive circuit 19 for the lens driving device. That is, the reflected light from the target is made incident on the image sensor, and the image sensor's video signal is processed to detect the optical axis and focus error, and the automatic mirror gimbal and the lens driving device are driven to adjust the optical axis. and focus adjustment.

Generally, as the output of laser light increases, the diameter of the laser beam becomes large, so the focal length of the condensing lens becomes a long focal point of about 1 m. In order to detect the focused state of the laser beam at the target position with high precision, it is necessary to increase the horizontal and vertical magnification, and a telephoto optical system with a long focus (approximately 10 m) is required as the error detection means. Due to space constraints, the second
As shown in the figure, a reflector for switching the optical path is essential.

The error detection means should originally detect the angular fluctuations of the reflecting mirrors 1 and 2, but since the angular fluctuations of the reflecting mirrors 13 and 14 in the detection means are added to the error signal, Unable to detect accurate optical axis error.

In addition, since the lenses 11 and 12 are separated, it is difficult to adjust the optical axis and focus within the error detection means, and as a result, the pattern imaged on the image sensor may be affected by axial eccentricity. There is a drawback that the ability to detect minute changes in the beam divergence angle of reflected light from the target due to slight deviations in the optical axis direction between the condensing lens 3 and the target 9 of the laser beam condenser is poor.

As explained above, with conventional devices, it is difficult to optically adjust the error detection means, and the optical axis of the error detection means may fluctuate, making it impossible to detect the optical axis and focus error of the laser beam focusing device with high precision. There were flaws.

An object of the present invention is to provide a laser beam focusing device having an optical axis and focus error detection means that can easily adjust the optical axis and focus of the error detection means and detect the optical axis and focus error with high precision. .

The configuration of the apparatus according to the present invention includes an optical axis adjusting means and a focus adjusting means for accurately converging a laser beam at the center of a spherical target, and receiving reflected light from the target of the laser beam, and adjusting the optical axis. A laser beam focusing device comprising an optical axis and a focus error detection means for detecting a fluctuation error of the means and the focus adjustment means and outputting a correction signal,
An optical arrangement for guiding the reflected light from the target to the optical axis and focus error detection means includes a lens receiving the reflected light, a reflecting mirror disposed at a condensing position of the lens, and light reflected by the reflecting mirror. a relay lens that focuses the light onto the optical axis and the focus error detection means; a reticle that is arranged corresponding to the reflector and can be switched to the position of the reflector; and a slide that slides the positions of the reflector and the reticle. and a light source for illuminating the reticle.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 3 is a diagram showing an embodiment of the present invention, in which 20 is a relay lens, 21 is a reticle, and 22 is a diagram showing an embodiment of the present invention.
23 is a slide mechanism for inserting and removing the reflecting mirror 13 and reticle 21 from the optical path; 23 is a rotation stage for rotating the reflecting mirror and reticle around the focal point of the laser beam by the lens 11; 24 is a white light source; 25 is an interference filter. The other components are similar in their functions, as indicated by the same symbols as in the conventional example in FIG. A reflecting mirror 13 is placed at the position where the laser beam is focused by the lens 11 to switch the optical path, and the relay lens 20
The optical system is constructed so as to obtain a composite focal length similar to that of the optical system shown in FIG. A reticle 21 is placed at the reflecting mirror installation position to form an imaging point, and a reference point for optical adjustment of the lens 11 and the relay lens 20 is provided. The reticle 21 is made of a translucent diffusing material with a crosshair scale drawn thereon, and the slide mechanism 22 is adjusted so that the intersection of the crosshairs coincides with the optical axis of the lens 11.

This adjustment can be made by injecting visible light such as a He-Ne laser onto the optical axis of the lens 11 and moving the reticle so that the center of the reticle and the beam position match, and this position switches between the reflecting mirror and the reticle. The stopper reference of the slide mechanism 22 is adjusted to the actual installation position to obtain position reproducibility.

After the above adjustment, the laser beam condenser is installed at a predetermined position. Optical axis alignment with the laser beam is facilitated by setting the reticle perpendicular to the optical axis of the lens 11 using a rotating stage and adjusting the position of the detection means so that the beam condensing position coincides with the center of the reticle. will be achieved.

The optical adjustment of the relay lens 20 is performed using the rotation stage 2.
3, the reticle 21 is made perpendicular to the optical axis of the relay lens 20, and the white light source 24 illuminates the reticle. The wavelength of the illumination light is selected by an interference filter 25 in order to match the wavelength of the laser beam.

The video signal from the image sensor 15 is displayed on a TV monitor, and the focus and optical axis of the relay lens 20 and the image sensor 15 are adjusted so that the reticle image is clear and the center of the reticle coincides with the center of the image sensor. In this state, the reticle is switched to a reflector to receive the laser beam, and the reflector 13 and relay lens 2
The focus of the lens 11 can be easily adjusted by simultaneously moving the image sensor 15 and the image sensor 15 in the optical axis direction of the lens 11. This adjustment can also be performed by moving the lens 11 in the optical axis direction so that the light condensing pattern on the reticle surface is minimized when adjusting the optical axis of the lens 11.

The laser beam used during the above focus adjustment is a reflected beam from the target after the initial optical adjustment of the laser beam concentrator has been completed to accurately focus the beam on the center of the target, and is a nearly parallel beam. .

Furthermore, in the optical arrangement described above, even if the angle of the reflecting mirror 13 changes, the image sensor 15
The focus position of the beam remains unchanged.

As is clear from the above description, the laser beam focusing device according to the present invention includes optical adjustment means within the optical axis of the laser beam and the focus error detection means, and the optical path used by the error detection means. By optically arranging the optical axis so that the optical axis of the detection beam does not change due to changes in the angle of the switching reflector,
This has the effect of facilitating optical adjustment and detecting optical axis and focus errors with high precision.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a general laser beam focusing device, FIG. 2 is a block diagram of a conventional optical axis and focus error detection means, and FIG. 3 is a block diagram of an embodiment of the present invention. 1, 2... Reflector, 3... Condensing lens, 4, 5
... Automatic mirror gimbal, 6 ... Lens drive device, 7 ... Vacuum chamber, 8 ... Vacuum shield glass, 9 ... Target, 10 ... Optical axis and focus error detection means, 11, 12 ... Lens, 13 ，
14...Reflector, 15...Image sensor, 1
6... Signal processing circuit, 17, 18... Automatic mirror gimbal drive circuit, 19... Drive circuit, 20...
Relay lens, 21... Reticle, 22... Slide mechanism, 23... Rotating stage, 24... White light source, 25... Interference filter.

Claims (1)

[Scope of utility model registration request] Optical axis adjusting means and focus adjusting means for accurately focusing the laser beam on the center of a spherical target, and receiving the reflected light from the target of the laser beam, and adjusting the fluctuation error of the optical axis adjusting means and the focus adjusting means. At a laser beam focusing position, the reflected light from the target is guided to the optical axis and the focus error detection means at a laser beam focusing position, which is equipped with an optical axis and a focus error detection means for detecting the optical axis and outputting a correction signal. a receiving lens, a reflecting mirror disposed at a focusing position of the lens, a relay lens that focuses the light reflected by the reflecting mirror onto the optical axis and the focus error detection means, and a relay lens corresponding to the reflecting mirror. A laser beam focusing system comprising: a reticle that is arranged and can be switched to the position of the reflecting mirror; a sliding mechanism that slides the positions of the reflecting mirror and the reticle; and a light source for irradiating the reticle. Device.