JPS6110738A - Apparatus for monitoring state of optical fiber - Google Patents

Abstract

PURPOSE:To ensure the monitoring of the deteriorated state, by converging light by condenser lens, inputting optical energy into optical fiber, detecting the scattered light by a light detecting element, which is provided coaxially in parallel in a part of the optical fiber, and converting the scattered light into an electric output. CONSTITUTION:Carbon dioxide gas laser light 4 is emitted from a carbon dioxide gas laser oscillator 3 and dent by a mirror. The light is converged by a condenser lens 5 and inputted to an optical fiber 8 through a window 7 provided at an incident part 6 of the optical cable. The transmitted laser light is converged by an output side condenser lens 10, which is provided at hand piece part 9. The light is guided to the diseased part and used for operation. The scattered light yielded in the vicinity of the emitting end is absorbed by a cylinder part 16. The temperature increase at the part 16 is converted into the resistance value of a heat sensitive element 15 comprising a thermistor. The value is amplified and converted into an electric output corresponding to the resistance value by an amplifier converter 19 thrugh a lead wire 18. Thus layer energy transmitted through the optical fiber 8 is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a laser beam that is incorporated into a laser processing device, etc. that guides a laser beam to a processed or affected area through an optical fiber and performs welding, cutting, incision of the affected area, evaporation, etc. This invention relates to a fiber condition monitoring device.

Conventional configurations and their problems Laser processing devices or laser surgical devices that use YAG laser light or CO2 laser light use a plurality of reflecting mirrors to direct the laser beam to the processing site or surgical site. The so-called mirror joint method that leads to
There is an optical fiber method that is currently being put into practical use. The mirror articulation method has problems such as poor operability during processing or surgery and misalignment of the mirror angle due to vibration, and in order to solve these drawbacks, it has been desired to put optical fiber into practical use as a waveguide.

For Co2 laser light, KRS-6, a mixed crystal of thallium iodide and thallium bromide, is cited.

KR8-5 has the disadvantage that it will break if bent beyond a certain curvature, so it must be used carefully with curvature limits.

If the fiber breaks despite the curvature limit and melts due to localized heat concentration, a high-power laser beam will penetrate the outer jacket and irradiate the patient or operator. Danger may occur.

In addition, the vapor generated when KRS-5 melts may have some effect on the human body, so it is important to prevent the fiber damage mentioned above and constantly monitor the deterioration state of the optical fiber. It was absolutely necessary to do so.

However, although various monitoring methods have been tried in the past, they have various drawbacks and none are perfect.

For example, there is a method of wrapping a resin tape whose electrical resistance changes with temperature around the entire length of the optical fiber and monitoring the sudden temperature rise due to melting or breakage through the resin tape. The characteristics of the optical fiber were adversely affected by loss of flexibility and contact with the resin tape, which affected the light transmission characteristics of the optical fiber. In addition, there is a means to monitor the state of the fiber by using a photodetector to detect several pieces of light energy emitted from the optical fiber on the output side of the optical fiber, but this requires a complicated configuration on the output side and is small. We were unable to respond to the ever-changing handpieces.

OBJECT OF THE INVENTION The present invention has been made in view of the above-mentioned conventional drawbacks, and provides a method for reliably monitoring the deterioration or damage state of optical fibers and making it compatible with various types of handpieces. The purpose is to

Structure of the Invention The present invention comprises a light energy generating means, a condensing lens for making the light energy enter the light energy bar, and a photodetecting element that is installed parallel to and coaxially with a portion of the optical fiber and that receives and detects scattered light from the optical fiber. and a converter that converts the output of the photodetector into an electrical output.

Description of examples Embodiments of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a configuration diagram of a carbon dioxide laser scalpel device consisting of a laser main body 1 incorporating an optical fiber condition monitoring device according to the present invention and an optical cable 2. As shown in FIG. Carbon dioxide laser light 4 emitted from the carbon dioxide laser oscillator 3 and represented by a broken line
is bent by the mirror 5 and condensed by the condensing lens 6.

The focused laser beam passes through the window 7 at the entrance part 6 of the optical cable, and the KR transmits the carbon dioxide laser beam.
The light enters the input end of an optical fiber 80 made of an infrared optical material such as S-TS. The transmitted laser light is focused by an output-side condensing lens 10 provided on the handpiece section 9 and guided to the affected area 11 to perform surgeries such as incision, evaporation, and hemostasis.

In addition, a chuck section 11 provided on the optical fiber input section 6
, and is covered with a protective tube 12 made of metal such as stainless steel.

The optical fiber at the output section of the handpiece section 9 is not chucked and has a free structure in order to absorb thermal expansion of the optical fiber over its entire length.

A photodetector 13 detects scattered light 14 scattered from the optical fiber 8.

As shown in FIG. 2, the photodetector 13 consists of a heat sensitive element 15 made of a thermistor and a ceramic material coated with a light absorber on the inner surface, and has a thin cylindrical part 1 in which the heat sensitive element is brought into close contact.
6 and the metal tube 12, a cylindrical joint part 17 made of the same material as the cylindrical part 16, and lead wires 18 drawn out from both ends of the heat sensitive element 16.

The amplification converter 19 amplifies and converts the resistance value of the heat sensitive element into an electric output corresponding to the resistance value, and the scattered light is transmitted to the cylindrical portion 1.
If 6 is not irradiated, it will be 0.

Next, the operation will be explained.

When a laser beam is transmitted through an optical fiber, scattered light corresponding to the energy of the laser beam incident from the optical fiber is also generated near the output end of the optical fiber.

The generated scattered light is absorbed by the thin cylindrical part 16, and the cylindrical part 1
6 is raised, the thin film thermistor inside the cylindrical part 16 converts the scattered light into a resistance value corresponding to the energy of the scattered light, and the amplification converter converts it into a stain signal. That is, by constantly detecting this electric signal, the energy of the laser transmitted to the optical fiber can be detected.

FIG. 3 shows the relationship between the state of the optical fiber and the electrical signal. The region (2) corresponds to the case where the optical fiber is normal, and as described above, shows an electrical signal corresponding to the energy of the incident laser light.

However, if a flaw occurs in the optical fiber for some reason, conversion to a higher-order mode occurs due to diffuse reflection from the flaw, increasing scattered light and increasing the electrical signal. Also,
If the optical fiber is fused, the laser light will no longer be propagated to the photodetector, and the electrical signal will become zero.

As described above, by detecting the electrical signal of the amplification converter, it is possible to detect the occurrence of flaws or fusing of the n-mi optical fiber.

Furthermore, by detecting the electrical signal in the region (2), it is also possible to know the laser light energy transmitted to the optical fiber.

In the embodiment, the photodetecting element was provided near the output side, but it is also possible to monitor the state of the optical fiber even if it is provided in the middle of the optical fiber.

As described in detail, according to the present invention, the state of the optical fiber can be constantly and reliably monitored by detecting scattered light near the output end of the optical fiber using a heat sensitive element.

Furthermore, by arranging the photodetector parallel and coaxially with a portion of the optical fiber, the configuration on the output side of the optical fiber is simplified and can be applied to various types of handpieces.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram showing a part of a laser scalpel device including an optical fiber condition monitoring device according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a photodetecting element of the device, and FIG.
The figure is a characteristic diagram for explaining the device. 3... Laser oscillator, 4... Laser light,
6...Condenser lens, 8...Optical fiber, 12...Protection tube, 13...Photodetector, 17...Amplification converter.

Claims (2)

[Claims] (1) A light energy generating means, an optical fiber that transmits the light energy generated by the light energy generating means, a condensing lens that focuses the light energy and makes it enter the optical fiber, and a part of the optical fiber. An optical fiber condition monitoring device comprising: a photodetection element that is installed parallel to and coaxially with the optical fiber and receives and detects scattered light from the optical fiber; and a converter that converts the output of the photodetection element into an electrical output. (2) The optical fiber condition monitoring device according to claim 1, wherein the optical fiber is covered with a protective tube made of metal or resin.