JPS6049504B2 - Laser scalpel device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved laser scalpel device.

In a laser scalpel device that uses a CO2 laser with a wavelength of 10.6μ as a light source, there are two methods for guiding laser light to a surgical site.

One is called the mirror-articulated method, which uses multiple mirrors to guide laser light to arbitrary positions and directions, and the other is
This method involves passing laser light through a thin, highly flexible optical fiber to guide the light to any desired position and direction. The present invention relates to a method using optical fibers, and particularly aims to improve safety when using optical fibers. Optical fibers mainly made of quartz, which are used for ordinary optical communications, are extremely flexible and can transmit light from visible light to near-infrared light with wavelengths of around 1μ to 2μ with low loss. , almost no CO2 laser light with a wavelength of 10.6μ passes through.

Therefore, CO. Optical fibers for laser scalpels are made of materials that have relatively good light transmission characteristics for laser light with a wavelength of 10.6μ, such as thallium bromide (hereinafter referred to as KR).
S-5] is processed into a fiber and used, but this fiber has a polycrystalline structure and is therefore brittle and has the disadvantage of breaking if bent beyond a certain curvature. As an example, in the case of a KRS-5 fiber with a diameter of 1, the radius of curvature is about 12 cm at its limit, and if it is bent beyond this, it will break. For this reason, the fiber is covered with a curvature-limiting jacket, which allows it to bend freely up to a certain curvature with almost no resistance, but prevents it from bending beyond a certain curvature, improving safety. By the way, if an optical fiber is broken in the middle while using a laser scalpel device, the optical fiber has a polycrystalline structure, so the absorption of light at the broken surface increases significantly, the temperature of this broken part increases, and eventually dissolve.

Since the melting temperature of KRS-5 is approximately 350'C▼,
The temperature around the fractured part also rises, and if left untreated, it will also affect the outer covering. If a laser beam is directly emitted from the outer sheath of the optical fiber due to breakage, the user and others will be in a very dangerous situation. In addition, since such optical fibers pass a large amount of energy through the thin optical fiber, the optical fiber absorbs light (loss due to optical fiber), which causes the temperature of the optical fiber to rise, causing melting in a part of the optical fiber. In such a case, there may be a dangerous situation in which the laser light directly exits from the outer sheath of the optical fiber, similar to the above case. In order to avoid such a situation, it has conventionally been proposed to measure the temperature of the optical fiber and to immediately stop laser oscillation if a temperature rise is detected. A concrete method for detecting the temperature of an optical fiber is to wrap a resin tape around the optical fiber whose electrical resistance changes depending on the temperature, but this method reduces the flexibility of the optical fiber. or affect the light transmission characteristics of the optical fiber. or cause In order to eliminate such drawbacks, the present invention detects infrared rays that are generated in a high-temperature part within an optical fiber, propagate within the optical fiber, and are emitted from the end face of the optical fiber to the outside of the optical fiber.
By detecting the temperature rise of the bar and stopping the laser oscillation, there is no need to install resin tape etc. on the optical fiber, and the flexibility and light transmission characteristics of the optical fiber can be maintained well. This provides a laser scalpel device that can

Embodiments of the present invention will be described in detail below with reference to the drawings.
The figure shows the configuration of an embodiment of the present invention, in which 1 is a laser oscillator, 2 is a lens for condensing a light beam output from the laser oscillator, and the lens 2 allows the light beam to be focused in a predetermined direction. The input end 3a of the optical fiber 3 is installed at a position where the light is focused to a size of , and effectively guides the light beam output from the laser oscillator to the optical fiber 3.

Reference numeral 4 denotes an output lens that condenses the light emitted from the output end 3a of the optical fiber 3.

In this way, the focused light can be used for incisions or other surgical procedures. The dash-dotted line shown in 5 indicates one path of the light beam for convenience of explanation.

Reference numeral 6 denotes a beam splitter, which is composed of a multilayer filter so that nearly 100% of the laser beam with a wavelength of 10.6 μm is transmitted, but has good reflection characteristics for other wavelengths.

7 is a filter that transmits light of a predetermined wavelength.

8 is a lens that focuses the light transmitted through the filter 7; 9 is a photodetector; 10 is a signal processing circuit that amplifies the output signal of the photodetector 9, shapes the waveform, and performs level detection; 11 is a display alarm device; 12 is a laser control circuit.

Next, the operation of this embodiment configured as above will be explained.

When a portion of the optical fiber 3 is broken, scratched, impurities, etc. and absorbs laser light significantly, the temperature of the portion increases locally. When light energy is continuously supplied, the temperature of the portion reaches the melting temperature of the optical fiber 3. For example, in the case of an optical fiber made of KRS-5 that transmits a CO2 laser, the melting temperature is about 350°C. Energy is radiated from the high temperature part to the surroundings according to the Stefan-Boltzmann law. The total amount of energy emitted is EOT4.
Here, t is the emissivity, and σ is the Ftefan constant (5.668
7×10 −12 watt cm −20 K−4), T is the temperature expressed in absolute temperature. If the room temperature is approximately 300'K and the melting temperature of KRS-5 is 620X, the energy radiated from the melted part is 4 times (620/300) compared to the temperature near room temperature, which is a large value of about 18 times. becomes. The wavelength range of the emitted light energy changes depending on the temperature, but it extends from the far infrared region to the near infrared region, or in the case of high temperatures, to the visible region, but the wavelength with the highest energy is the Vienna wavelength. As a displacement law, λm=2.
897/T. Here, if T is an absolute temperature, the unit of λm is micron [μ]. In this formula, T
= 300'K and T = 620'K to find their respective λm, in the case of T = 300'K, it is approximately 9.7
micron, and in the case of T=62CfK, it is 4.7
Becomes a micron. That is, a large amount of infrared rays having a peak wavelength around 4.7 microns are emitted from the melted portion of the optical fiber. Of this energy emitted within the optical fiber 3, a part is radiated to the outside from the surface of the optical fiber 3 near the high-temperature part, but most of the remaining energy is emitted from the optical fiber 3.
propagates inside toward both end faces. The refractive index of KRS-5 is approximately 2.7, and the transmission band width is also 0.5 microns to 40
Since the infrared rays are as wide as microns, the infrared rays emitted as described above undergo repeated reflection on the surface of the optical fiber, reach both end faces without significant attenuation, and are radiated to the outside of the optical fiber 3 from both end faces. The infrared rays emitted from the incident end 3a are turned into substantially parallel light by the lens 2, and enter the beam splitter 6, where they are reflected.

Only a predetermined wavelength band of the infrared rays reflected by the beam splitter 6 is selected by a filter 7, and then passed through a lens 8.
The light is focused on the light receiving surface of the photodetector 9. Photodetector 9
The output signal is input to the signal processing circuit 10, where it is amplified and
After the waveform is shaped, its level is detected. and,
When this level reaches a predetermined dissolution detection level, the signal processing circuit 10 outputs a signal to the display alarm device 11 and the laser control circuit 12 to notify the operator of the laser scalpel of the abnormality, and also outputs a signal to the laser oscillator 1. control to stop the output of laser light. As explained above, according to the present invention, an abnormality in the optical fiber can be detected and the laser beam output can be stopped without adding anything to the optical fiber itself, thereby improving the flexibility and light transmission characteristics of the optical fiber. It has the unprecedented advantage of being able to maintain

[Brief explanation of the drawing]

The figure is a diagram showing a configuration diagram of an embodiment of the present invention. 1...Luther oscillator, 2...Luns, 3...
...Optical fiber, 3a...Incidence end, 6
...Beam splitter, 7 ... Filter, 9 ... Photodetector, 10 ... Signal processing circuit, 11 ... Loser control circuit.

Claims (1)

[Scope of Claims] 1. A laser oscillator, a flexible optical fiber that transmits a laser beam output from the laser oscillator, and a lens that makes the laser beam output from the laser oscillator enter an incident end face of the optical fiber. In the laser scalpel device, a beam splitter is provided between the laser oscillator and the incident end face, and the beam splitter is provided between the laser oscillator and the incident end face, and the beam splitter transmits most of the laser light and reflects light of wavelengths other than the laser light. a detector that detects the light reflected by the
A signal processing circuit that processes a signal output from the detector and a laser control circuit that controls the laser oscillator according to the output signal from the signal processing circuit are provided, A laser scalpel device characterized in that the infrared rays output from the incident end face are detected by the detector via the beam splitter, and the output of the laser light from the laser oscillator is stopped by the laser control circuit. 2. Claims characterized in that the beam splitter is provided between the laser oscillator and the lens, and a filter that does not transmit laser light is provided between the beam splitter and the detector. The laser scalpel device according to item 1. 3. The laser oscillator is a CO_2 laser oscillator,
2. The laser scalpel device according to claim 1, wherein the optical fiber is an optical fiber made of thallium boroiodide.