JPH0320075B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a device for attenuating the output of laser light in a laser treatment device used as a laser scalpel, for example.

"Prior art and its problems" _Co2 lasers and Nd-YAG lasers are generally required as laser treatment devices that utilize the thermal energy of laser light, but when used under an endoscope,
Nd-YAG lasers are often used because they are efficiently transmitted through flexible laser fibers.
In treatment using this Nd-YAG laser, contact therapy has been put into practical use, in which a transparent sapphire material is connected to the tip of the laser fiber, and the tip of this sapphire material is brought into contact with the affected area to incise and coagulate the affected tissue. .

Compared to conventional non-contact therapy, this contact therapy uses transparent sapphire material that comes into direct contact with the affected area, so the laser light is reflected by the surface tissue of the affected area.
Since scattering is suppressed, therapeutic effects can be expected with low output. Particularly when the purpose is coagulation, non-contact therapy requires an output of 30W or more, whereas contact therapy requires about 1/3 of that output.
Even with an output of 10W or less, the same effect as non-contact therapy can be obtained.

On the other hand, when this Nd-YAG laser is used for the purpose of hemostasis, for example, a high output of about 100 W is required. Therefore, in order to use the Nd-YAG laser as a general-purpose device, it must satisfy the oscillation function from a low output of about a few W to a high output of 100 W or more.

However, the conventional Nd-YAG with an output of 100W
In lasers, the population inversion threshold for starting laser oscillation corresponds to a power output of nearly 10W;
It is not possible to stably output a low output of about 10W. That is, if current control is performed to change the light intensity of the excitation lamp to correspond to a low output, the oscillated laser light will become extremely unstable. For this reason, in order to perform the above-mentioned contact therapy, it was actually necessary to use a special low-power Nd-YAG laser.

In addition, it is generally considered to install an absorption filter such as an ND filter in the laser beam path in order to attenuate the laser beam and reduce its output, or to use a splitting prism to irradiate only a portion of the laser beam to the affected area. In the former case, the target laser light output is several tens of watts or more, so the energy causes thermal damage such as cracks in the ND filter, while in the latter case, a large heat sink such as a water cooling method is required to process the split light. The problem is that it is necessary.

Furthermore, against this background, attenuators are used in which light-transmitting parts and light-shielding parts are provided alternately around a rotating disk, but this attenuator has problems due to malfunctions. If the light shielding part happens to stop in the laser optical path, there is a risk that thermal trouble will occur. In addition, if a transparent part stops in the laser beam path, the laser light that should be attenuated and irradiated will be irradiated without being attenuated, resulting in an increase in output value and the risk of perforation of the irradiated area, which is a big problem. It was hot. Furthermore, if the shutter mechanism that sets the laser irradiation time, which is located between the laser oscillator and the attenuator, opens when the rotating disk has not reached a predetermined rotational speed, the laser beam may not be irradiated to the affected area.

``Purpose of the Invention'' The present invention is a general-purpose laser beam attenuator that solves this problem of conventional laser beam attenuators and can cover from low output to high output, and that attenuates laser beams reliably. The purpose of the present invention is to obtain a highly safe device that can be irrigated after treatment.

"Summary of the Invention" The present invention provides a laser beam attenuation device using an attenuator, which checks the rotational state of a rotating disk of the attenuator, and irradiates the laser beam only when the rotational speed of the rotating disk reaches a predetermined value. This was done based on the idea of enabling the shutter mechanism that sets the time to operate. That is, the present invention provides a device including a laser oscillator, an attenuator, and a shutter mechanism, further including a rotation detector for a rotating disk of the attenuator, and a rotation speed of the rotating disk detected by the rotation detector. The present invention is characterized in that it is provided with a shutter drive circuit that enables the shutter mechanism to be driven when a predetermined value is reached.

"Embodiments of the Invention" The present invention will be described below with reference to illustrated embodiments. FIG. 1 is a circuit block diagram of a laser beam attenuator according to the present invention. The laser oscillator 11 is powered by the power supply device 12, operates, and emits laser light. A shutter mechanism 13 is attached to this laser oscillator 11. This shutter mechanism 13 has an irradiation switch 13a and an irradiation time setting device 13b, and when the shutter drive circuit 30 is in the on state, the irradiation switch 1
When the opening 3a is closed, the opening is opened for the irradiation time set by the irradiation time setter 13b to emit laser light, and this function is achieved by, for example, turning on and off the oscillator of the laser oscillator 11.

A rotating disk 16 of an attenuator 15 is placed in the optical path of the laser beam emitted from the shutter mechanism 13.
This rotating disk 16 is driven by a drive motor 17, and has light-transmitting portions 16a and light-shielding portions 16b alternately formed on its outer periphery. The attenuation rate of the laser beam is determined by the ratio of the circumferential lengths of the light-transmitting portion 16a and the light-blocking portion 16b, and in this example, this ratio is 1:4. The laser beam that has passed through the rotating disk 16 is transmitted through the laser fiber 18.
is incident on the 19 is a power supply device for the drive motor 17.

The attenuator 15 is provided with a rotation detector 20 . The rotation detector 20 includes a photocoupler 21 placed across the rotating disk 16, a differentiating circuit 22 that receives the output of the photocoupler 21, a waveform shaping circuit 23 that shapes the output waveform of the differentiating circuit 22,
Upon receiving the output of the waveform shaping circuit 23 and the clock pulse from the reference clock pulse generator 24,
It consists of a pulse interval measuring device 25 that measures pulse intervals, and a determination circuit 26 that determines from this pulse interval whether the number of rotations of the rotating disk 16 has reached a certain value. The determination circuit 26 is connected to the shutter drive circuit 30, and when the rotational speed of the rotary disk 16 reaches a certain value, the shutter drive circuit 30 is turned on and the shutter mechanism 13 is activated by the irradiation switch 13a. drive (shutter open) becomes possible. Further, the determination circuit 26 is connected to a display device 27, and when the rotational speed of the rotating disk 16 reaches a certain value or more, the display device 27 lights up, for example.

This device having the above configuration operates as follows. When the rotary disk 16 of the attenuator 15 rotates, the transparent part 1
Every time 6a passes, a pulse wave a shown in FIG. 2 is generated in the photocoupler 21. This pulse wave a is
Next, the differential circuit 22 generates a differential wave b, and the waveform shaping circuit 23 generates a shaped wave c.
It is input to the pulse interval measuring device 25. The pulse interval measuring device 25 receives the reference clock pulse wave d input from the reference clock pulse generator 24, and
The number of reference clock pulse waves d included between adjacent shaped waves c is counted. If this count value is within a predetermined constant value, the determination circuit 26 turns on the shutter drive circuit 30 and the display device 27. Then, the shutter mechanism 13
When the irradiation switch 13a is activated and the irradiation switch 13a is operated, it opens for the time set by the irradiation time setting device 13b, and the laser fiber 18 is irradiated with the laser light attenuated by the attenuator 15.
That is, in the illustrated example, the light transmitting part 16a and the light shielding part 1
Since the ratio of the circumferential lengths of the laser beam 6b is 1:4, the output power of the laser oscillator 11 is reduced to 1/5 and is applied to the laser fiber 18 to irradiate the affected area.

Note that the rated rotation speed of the rotating disk 16 is determined by the shutter mechanism 13, which is set by the irradiation time setting device 13b.
If the opening time per operation is short, it is necessary to take this into account when setting. For example, when the opening time of the shutter mechanism 13 is set to 0.1 seconds, the laser beam must pass through the transparent portion 16a of the rotating disk 16 within this set time, so the rotation speed of the rotating disk 16 is , must be at least 2.5 revolutions. That is, the number of rotations of the rotating disk 16 is N, the ratio of the length in the circumferential direction of the light shielding part 16b and the transparent part 16a of the rotating disk 16 is K. The opening time per shutter mechanism 13 (laser irradiation When the condition N>1/KT is satisfied, the rotation detector 20 turns on the shutter drive circuit 30 so that the shutter mechanism 13 can be driven.

On the other hand, if the number of reference clock pulse waves d between adjacent shaped waves c is greater than (or less than) the specified value, the number of rotations of the rotating disk 16 is too low (or too high).
Therefore, the determination circuit 26 of the rotation detector 20 turns off the shutter drive circuit 30 so that the shutter mechanism 13 cannot be driven, and does not operate the display device 27.

"Effects of the Invention" As described above, the laser light attenuation device of the present invention has the following features:
In a device that attenuates laser light using a rotating disk that has a light-transmitting part and a light-blocking part, the number of rotations of the rotating disk is detected, and if the number of rotations is not within a certain range, the laser beam is attenuated. By disabling the shutter mechanism that sets the irradiation time, it is possible to avoid the danger of excessive laser beam irradiation to the human body, and also to prevent the laser beam from irradiating the light shielding part of the rotating disk for a long time. It is possible to prevent accidents such as damage and fire caused by Therefore, it is possible to provide a laser beam attenuation device that is highly safe and practical.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of the laser beam attenuation device of the present invention, and FIG. 2 is a waveform diagram showing waveforms in each circuit of a rotation detector. 11... Laser oscillator, 13... Shutter mechanism, 13a... Irradiation switch, 13b... Irradiation time setter, 15... Attenuator, 16... Rotating disk,
16a...transparent part, 16b...shading part, 18...
Laser fiber, 20... Rotation detector, 30...
Shutter drive circuit.

Claims (1)

[Claims] 1. A laser oscillator; an attenuator having a rotating disk in which light-transmitting parts and light-blocking parts are alternately formed on the outer periphery of the laser oscillator; and the above-mentioned laser oscillator and attenuator. A laser beam attenuation device comprising a shutter mechanism for opening and closing an optical path between the two and setting the laser irradiation time, further comprising: a rotation detector of a rotating disk of the attenuator; detected by the rotation detector; A laser beam attenuator comprising: a shutter drive circuit capable of driving the shutter mechanism when the rotational speed of the rotating disk reaches a predetermined value. 2. In claim 1, the number of rotations of the rotating disk of the attenuator is N, the ratio of the circumferential lengths of the light shielding part and the transparent part of the rotating disk is K, and the number of rotations per shutter mechanism is When the open time (laser irradiation time) is T, the rotation detector is a laser beam attenuation device that enables the shutter mechanism to be driven when the condition N>1/KT is satisfied.