JPS601016B2 - Laser erroneous irradiation prevention device - Google Patents

Description

[Detailed Description of the Invention] This invention substantially limits the laser beam length to a finite degree by setting the laser irradiation area within a certain distance along the beam direction from the laser irradiation end, thereby preventing human error. This invention relates to a device for preventing erroneous laser irradiation that prevents accidental laser irradiation.

In the conventional device, a distance signal that determines the distance between the laser irradiation end and the object is obtained by measuring the laser reflected light 3 from the object 4 with the photodetector 2.

However, such a device has the disadvantage that, in the case of an object, especially a laser scalpel, there are large measurement errors due to differences in reflectivity of various biological tissues and the inclination of the reflecting surface. Therefore, according to a single detector 2, FIG.
There are three such as A' and A''. This is because the amount of reflected light changes depending on the inclination of the object and the difference in reflectance, making it difficult to set an accurate and stable irradiation area. The improvement of this invention is that by using two photodetectors and measuring their differential output, errors caused by differences in the frame or reflectance of the object are almost eliminated, making it accurate and stable. It is possible to set the irradiation area.

An embodiment of the present invention will be explained below using the drawings.

FIG. 2 shows the configuration of the present invention, in which numerals 2 and 5 indicate a pair of photodetectors. These photodetectors are provided with directivity using, for example, pipes. The photodetectors 2 and 5 can also be optical fibers; in this case, the photodetectors are installed at the other end of the optical fiber.The photodetectors 2 and 5 are tilted at a certain angle 8 with respect to the laser light. Next, the second
The operation of the configuration shown in the figure will be explained.

The characteristics of the detector 5 added in this invention are those of the detector 2 described above.
It is similar to B in the figure.

In this case as well, the characteristics will be B and B'' due to the influence of reflectance and slope. However, the intersection of the characteristic curves of these two detectors 2 and 5 occurs at a constant distance, and the reflectance and slope In this invention, we focused on the above point, and the intersection of the differential outputs of the two detectors 2 and 5 is almost unaffected by the inclination of the object or the difference in reflectance, and it can be detected at a constant distance. By using this phenomenon to detect this drop intersection and stop irradiation of the processing laser at this zero intersection, the laser irradiation area is accurately set.Next, we will confirm the operational effects of this invention. The results of the experiment conducted are shown below.The apparatus used in the experiment is shown in Figure 4.In the figure,
Although the photodetectors 2 and 5 are configured as one set, a pair is prepared as shown in FIG.

The outputs of these photodetectors 2 and 5 are amplified by amplifiers 6 and 7, respectively, and supplied as outputs A and B to an arithmetic unit 8. This arithmetic unit 8 outputs the sum and difference signals of both outputs A and B. This differential output is input to a comparator 9, and if it is less than zero, the shutter driver 10 closes the shutter 1, thereby realizing a function to prevent erroneous irradiation. Here, 13 is an object moving table to which a micrometer 12 is added, and the object 4 is covered with a bush. FIG. 5 shows the results of examining the influence of the reflectance of an object using such an apparatus.

In the figure, A, B, and C indicate different objects. Fifth
The characteristics shown are for the case where 8=300 and Q=00 in FIG. 4. Furthermore, the results of examining the influence of the inclination of the object are shown in Fig. 6. 8 and Q in FIG. 6 are the same as in FIG.
From FIGS. 5 and 6, it has been experimentally confirmed that the zero crossing point of the differential output according to the present invention is hardly affected by the object (type, inclination) and occurs at a constant distance. In the embodiment shown in Fig. 5, the shutter 11 is activated when the differential output is below a drop.
A comparator 9 and a shutter drive device 10 were added so as to close the erroneous irradiation prevention device, and the overall operation was confirmed.

The experimental results are shown in Figure 7. In FIG. 7, the shaded area indicates the irradiation area, and the white area indicates the stop area.

Note that Q' is the tilt of the object (white paper), A, B. C is a specific object. Although the laser irradiation stop distance was set to 31 points from the laser irradiation end, it worked accurately within the range of ±1 point. In the above explanation, it was written as a photodetector, but
Specifically, optical fiber can be used.

As described above, the present invention provides a device for preventing accidental irradiation with a very simple configuration that utilizes a visible laser for irradiation light that is equipped on a laser scalpel. This device according to the invention can set a stable irradiation area with almost no influence from the object, and can substantially limit the long cutting edge, which is a safety and operational problem in laser scalpels. . Furthermore, the present device according to the present invention has, in principle, a function of stopping laser irradiation even if a specular object enters the irradiation area, and can greatly contribute to improving the safety of laser surgery.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional device, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is a characteristic diagram for explaining the present invention, and Fig. 4 is an embodiment of the present invention. The block diagrams shown in FIGS. 5, 6, and 7 are explanatory diagrams for explaining the present invention. In the figure, 1 is Caesar. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 7 Figure 6

Claims (1)

[Claims] 1 The distance from the laser irradiation end to the target object is detected by differentially measuring the reflected light of the aiming laser beam from the target object using a pair of photodetectors, and when the distance is greater than or equal to a preset distance. A laser irradiation prevention device equipped with an automatic control mechanism that automatically stops irradiation of laser light other than the visible laser for aiming light when