JPH0466326B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laser light absorption device, and more specifically, to a high-energy laser such as a medical laser scalpel, a medical laser coagulation device, and a processing laser. The present invention relates to a laser light absorption device suitable for absorbing laser light and absorbing noise scattering in a measuring device that utilizes laser light scattering.

[Conventional technology] Conventional devices that absorb unnecessary laser light include:
1975 Utility Model Application Publication No. 51183 and the same No.
No. 51184 discloses a device for laser scalpel, and Patent Application Publication No. 146201 of 1985 discloses a device for measurement field.

With medical laser scalpels and processing lasers, until you aim at the affected area or processing area you want to treat,
The laser beam is evacuated to another safe location, and after aiming it, the laser beam is directed to the affected area or the area to be processed, but the laser beam used here has extremely high power. The above-mentioned laser beam evacuation location must be able to withstand this high power laser beam. As shown in FIG. 3, the device disclosed in Utility Model Publication Nos. 51-51183 and 51-51184 simply cuts a V-groove 3a on the surface of a heat sink 3 made of a material with good thermal conductivity, and then inserts a shutter (or Movable mirror) 2 makes this V
Laser light was guided onto the groove surface and converted into heat. In this case, 1 is the laser oscillator and 8 is the laser oscillator.
9 is an articulated manipulator that guides the laser beam, 5 is a focusing lens, and 6 is a workpiece or an affected area.

Furthermore, the absorption device disclosed in JP-A-60-146201 is a device that irradiates a laser beam onto an absorbing material at the Brewster angle and absorbs the laser beam, which equalizes the amount of heat converted in the traveling direction of the laser beam. We are trying to This attempts to absorb background laser light (which becomes noise) in laser scattering measurement.

[Problems to be Solved by the Invention] However, in the configurations disclosed in Japanese Utility Model Publications Nos. 51-51183 and 51-51184, the efficiency of laser beam heat exchange on the V-groove surface is poor, and the laser beam is scattered on the V-groove surface. Laser
The beam is directed toward an operator, a surgeon, an assistant, a nurse, etc., or is returned to the laser oscillator 1. When a laser beam is directed toward an operator or the like, it may inadvertently cause damage to the operator's skin or eyes, which is extremely dangerous. Also, when the laser beam returns to oscillator 1,
Decreases the stability of the oscillator or damages parts of the oscillator.

The device described in JP-A-60-146201 is preferable because it increases the absorption rate of laser light and does not scatter the laser light unnecessarily. This can be applied to extremely low outputs of about 100 mW, and in the case of high-power laser beams, even if the absorbing plate generates heat uniformly, the generated heat may melt or destroy the absorbing plate. It will be done.

Therefore, an object of the present invention is to propose an absorption device that can almost completely absorb even such high-power laser light.

[Means for Solving the Problems] The absorption device according to the present invention guides laser light through a minute aperture into the interior of a spherical or approximately spherical hollow absorber whose inner surface is preferably coated with an absorbing material, and , a cooling medium is brought into contact with the outer surface of the absorber to cool it, and the laser light that enters through the minute aperture for introducing the laser beam into the absorber is reflected on the inner surface of the spherical absorber. In this way, the injection to the outside through this minute opening is again minimized.

[Operation] According to this configuration of the present invention, the laser beam that enters the internal reflection space of the absorber is absorbed by the absorber while being repeatedly reflected inside. The heat absorbed and generated by the absorber tends to raise the temperature of the absorber, but since the absorber is cooled by the cooling medium, the temperature does not substantially increase. Since it only has a small aperture for laser beam incidence, not only is the amount of laser light that exits from this aperture extremely small, but the laser light introduced into this small aperture is focused along its optical axis. Since the optical axis of the condenser lens is shifted from the center of the absorber, the light reflected on the inner surface of the sphere serving as the absorber is almost never emitted from the minute aperture again.

[Example] An example shown in the drawings will be described below. FIG. 1 shows a central sectional view of the entire absorber according to the present invention, and FIG. 2 shows how laser light is multiple scattered within the absorber.

In FIG. 1, the absorption device according to the present invention includes a spherical absorber 50 that absorbs incident laser light during multiple internal reflections, and an outer housing 20 that houses the absorber 50. The outer casing 20 is
It has a box-like or cylindrical shape with an opening at one end, and the absorber 50 is placed inside through the opening, and the opening is sealed with the frame plate 24. 26 is an O-ring. A gap is provided between the absorber 50 and the inner surface of the outer casing 20, and a cooling medium 28 such as fluorocarbon gas is passed through the gap to cool the absorber 50. For the coolant 28, the outer housing 20 is provided with an inlet pipe 30 and an outlet pipe 32 for the coolant 28.

An opening is provided in the frame plate 24 at a position offset from the center thereof, and a condenser lens 34 is fixed to this opening portion with a lens holding ring 36. The frame plate 24 includes a hollow cylindrical protrusion 38 inside the opening of the condenser lens 34 portion.

The absorbent body 50 has a substantially spherical inner surface,
Made of material with good thermal conductivity and heat resistance. The inner surface is made, for example, a rough surface with irregularities and/or black so as to easily absorb laser light (that is, convert it into heat), but preferably, as shown in FIG. An absorbent material 52 such as carbon graphact or black heat-resistant paint is applied.

In the illustrated example, the absorbent body 50 includes a sphere 50a that occupies the main part of the absorbent body 50 and has a partially cut-out spherical inner surface, and a flat cover 50b that seals the opening formed by the notch. cover 5
0b is fixed to the sphere 50a by known means.
53 is an O-ring. Sphere 50 of cover 50b
A hollow cylindrical protrusion 54 is provided on the opposite side of the cover 50b at a position offset from the center of the cover 50b.
b, and thus the absorber 50 is fixed to the frame plate 24.
The cover 50b is provided with a minute opening 56 at the center of the protrusion 54 for guiding the laser beam into the absorber 50, and this opening 56 is located approximately at the focal point of the condenser lens.

In the illustrated embodiment, if the radius of the inner spherical surface of the absorber 50 is R, the minute opening is R/2 from the center of the sphere.
It is preferable that the ball be provided at a position shifted laterally by 50b, and it is also preferable that the distance between the inner surface of the cover 50b and the center of the sphere be R/2.
By doing this, not only can the number of internal reflections of the laser beam be increased and the absorption rate can be increased in the illustrated shape, but also the principal ray of the incident light does not pass through the center of the sphere, so the reflected light is directed toward the incident optical axis. As a result, the reflected light on the inner surface of the sphere is rarely emitted from the minute aperture 56 again, and extremely effective absorption results can be obtained.

The drawings illustrate an example in which the absorber 50 is composed of a sphere 50a and a flat cover 50b, but instead of the flat cover 50b, a part of the internal spherical surface may be formed so that the internal space is spherical. A spherically curved cover having a surface that is curved may also be used. Further, the inner surface of the absorber 50 may be one that allows multiple reflections of the laser light entering the absorber without concentrating on a specific location. That is, it may be multifaceted or elliptical.

The thickness of the absorber 50 is preferably thinner to a certain extent so that the cooling effect of the cooling medium 28 is enhanced.
0, there is preferably a sufficient gap to allow passage of the cooling medium.

The minute opening 56 of the absorber 50 may be large enough to allow the introduction of laser light into the absorber 50.

In the illustrated example, the frame plate 2 to which the condensing lens 34 is fixed is shown.
The absorber 50 is fixed to the lens 4, which makes it easy to position the aperture 56 at the focal point of the condenser lens 34. However, it is clear that the present invention is not limited to this configuration. For example, the absorber 50 may be fixed to the outer housing 20 such that both the inner and outer surfaces of the absorber 50 are spherical and the minute aperture 56 is located at the focal point of the condenser lens 38 .

Furthermore, in the case of the present invention, the outer casing 20 forms a gap between its inner surface and the absorber 50 to allow the cooling medium to pass therethrough. A pipe (for example made of copper) may be wrapped tightly around the outer surface of the absorber 50 and the cooling medium 28 may be passed through this pipe. However, the illustrated example has better cooling efficiency because the cooling medium contacts the absorber 50 over a wider contact area.

According to the present invention, the laser beam temporarily evacuated in a laser scalpel or the like is guided into the absorber 50 by the condensing lens 34. Then, as shown in Figure 2,
The laser beam is absorbed by the absorber 52 within the absorber 50, reflected at various places on the inner surface, and finally completely converted into heat. The heat generated by this absorption tends to raise the temperature of the absorber 50, but since the absorber 50 is constantly cooled by the cooling medium 28, the absorber 50
The temperature does not rise to such an extent that 2 and the absorber 50 are evaporated and destroyed. In addition, the laser beam is absorbed by the absorber 50.
Since the laser beam is multi-reflected in a diverging manner, the laser beam does not concentrate on a specific location, and therefore does not become locally heated.

[Effects of the Invention] As can be understood from the above explanation, according to the present invention, almost 100% of the temporarily evacuated laser light can be absorbed, so there is no damage to the operator or peripheral equipment. . Furthermore, the amount of laser light that returns to the laser oscillator side can be estimated to be almost zero, and will not destabilize or damage the laser oscillator.

[Brief explanation of the drawing]

FIG. 1 is a central cross-sectional view of an embodiment of an absorption device according to the present invention, and FIG. 2 is a cross-sectional view showing how the laser beam of the embodiment diverges. FIG. 3 shows an example of a conventional absorption device. 1... Laser oscillator, 3... Heat sink, 5
... Focusing lens, 6 ... Workpiece, 8 ... Laser beam, 9 ... Manipulator, 20 ... Outer housing, 24 ... Frame plate, 26 ... O-ring, 28 ...
...Cooling medium, 30...Introduction pipe, 32...Discharge pipe,
34...Condensing lens, 36...Lens holding ring, 3
8... Projection, 50... Absorber, 50a... Sphere, 50b... Cover, 52... Absorbent material, 53...
...O-ring, 54...Protrusion, 56...Minute opening.

Claims (1)

[Scope of Claims] 1. A thermally conductive absorber with a spherical or approximately spherical internal reflection space, and a microscopic laser beam inlet that occupies a position offset from the center and communicates with the internal space of the absorber. an aperture, a condensing lens that condenses the laser beam introduced into the minute aperture along its optical axis, and a guide channel along the outer peripheral surface surrounding the spherical or approximately spherical internal reflection space of the absorber. a cooling medium guide member configured to cool the absorber with A laser light absorption device characterized by being biased. 2. The device according to claim 1, wherein the absorbent body has an inner surface formed as a rough surface with unevenness. 3. The device according to claim 1 or 2, wherein the inner surface of the absorber is coated with an absorbing material having high absorption power corresponding to the wavelength range of laser light. 4. Any one of claims 1 to 3, wherein the guide member is configured in a gap between the outer circumferential surface of the absorbent body and the inner surface of an outer casing that accommodates the absorbent body. The device described in.