JPS6342430B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser device in which an output beam is interrupted by a mechanical shutter.

Conventionally, in order to control the output of a laser with a shutter, a beam splitter is used independent of the shutter, a certain percentage of the output beam is extracted, that beam is introduced into the output sensor, and the output value becomes the set value. Control the laser oscillation tube as follows.

This method requires the use of a special beam splitter, which complicates the structure and increases the cost.Furthermore, it is difficult to perform stable output control over a long period of time due to fluctuations in the beam splitting ratio of the beam splitter. be.

FIG. 1 shows a configuration example of a conventional output stabilization system using a beam splitter. An output beam 2 is emitted from the laser tube 1 . The intensity of the output beam 2 can be varied by controlling the power supply 3.

The output beam 2 emitted from the laser tube 1 is split into a main beam 2a and a sub beam 2b by a beam splitter 4, and the main beam 2a is immediately emitted to the outside when the shutter 5 is open (dotted line position in the figure). When the shutter 5 is closed, the light is reflected by the reflecting surface 5a and enters the absorber 6. The secondary beam 2b is incident on the output sensor 7. The power supply 3 is controlled by the output of the output sensor 7, creating a feedback loop and stabilizing the laser output. In such a structure, as mentioned above, the beam splitter 4 is required, which is extremely expensive and unstable, and therefore it is desired that this system be improved.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser device that has a simple configuration and stabilizes laser output without using a conventional beam splitter.

FIG. 2 shows an embodiment of the present invention.
The output beam 2 from the laser tube 1 immediately hits the shutter 5, and when the shutter is closed, the entire amount is reflected by the reflecting surface 5a and enters the output sensor 7. The power supply 3 is controlled by the output of the output sensor 7 to stabilize the laser output. In this method, when the shutter is open (at the dotted line position), the beam is emitted to the outside and no beam is incident on the output sensor 7. Therefore, the control of the power source 3 is cut off, the beam output goes out of control, and an excessive output is emitted. In order to prevent this, a switch 10 is provided that operates in conjunction with the operation of the shutter 5. When the shutter 5 is closed, the output of the output sensor 7 directly controls the power supply 3, and at the same time the sensor output is stored in a memory element. 11. When shutter 5 opens, switch 10 is connected to the output of storage element 11. This memory output stores and outputs the control signal immediately before the shutter 5 is opened.
There is no change in laser output due to opening and closing of the switch.
In this case, the laser output does not feed back to the power supply while the shutter is open, so the stabilizing effect cannot be said to be sufficient. That is, in the case of equipment that is used for a very short time, non-return operation during the shutter open time does not pose a practical problem. For example, in the case of a laser scalpel, the shutter is closed for 5 hours and the laser is opened for about 10 to 50 seconds. When the shutter 5 is closed again, the output beam is fed back again, and the laser output is stabilized and fluctuations over a long period of time can be prevented, so that the above embodiment is sufficiently suitable for practical use.

By the way, a thermopile type sensor is normally used as the output sensor 7 in this embodiment, but this often has a long thermal time constant (often about 0.5 seconds to 5 seconds). Due to this thermal time constant, even when a beam is incident, the sensor output does not rise immediately and there is a time delay in returning to the power source, during which time an excessive output is emitted from the laser. This is a phenomenon that occurs when the shutter is in closed mode, so there is no actual damage. However, when the shutter is restarted after a very short period of time after the shutter is closed, the transient signal from the sensor 7 is transferred to the memory element 11.
Since the laser beam is stored in the laser tube 1 and is output as is and the power source is controlled, there is a risk that an excessive output will be generated from the laser tube 1. To improve this, shutter 5
It may be possible to install a delay circuit that does not allow the time until restarting to be less than a certain amount of time, but for machines such as laser scalpels that repeatedly open and close the shutter in a short period of time, this would limit its use and be disadvantageous. Therefore, in this embodiment, the following control is performed in order to eliminate this drawback. FIG. 3 is a wiring diagram showing the shutter drive circuit, and FIG. 4 is a timing chart thereof. The shutter opening/closing command signal shown in Fig. 4A is applied to the input terminal in Fig. 3, and the monostable multi-2
2 and is added to the OR circuit 32, and the output becomes as shown in FIG. 4B.

T is determined by the retention time of the monostable multi 22. In other words, the output is held until a predetermined time T has elapsed after the shutter has been opened. Therefore, if the closing time is shorter than T time, no change will appear in the output. This output B drives the switch 10 shown in FIG. Therefore, switch 1 while the shutter is open.
0 is the memory element read mode, and this state is maintained even if the shutter is closed within T time.
Therefore, it is possible to prevent an abnormal increase in the laser output due to the delay in the operation of the output sensor 7 as described above.

The specified time T mentioned above is determined in accordance with the thermal time constant of the output sensor. It is usually several times the thermal time constant. In reality, it takes about 10 seconds.

In this way, in this embodiment, a practically stable laser output can be obtained without using a beam splitter.

As described above, the present invention is a laser device having a shutter for intermittently outputting a laser beam, in which when the shutter is closed, the shutter blade portion is used as a reflector to reflect the laser beam and apply it to the output sensor. In addition, the laser tube is controlled so that the output value of the output sensor becomes the set value, and has the advantage that stable laser output can be obtained with a simple configuration without using a beam splitter.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of a conventional laser device, Figure 2
3 is a schematic configuration diagram of a laser device according to an embodiment of the present invention, FIG. 3 is a wiring diagram showing a shutter drive circuit of the laser device, and FIG. 4 is a time chart showing its operation. 1... Laser tube, 2... Output beam, 20...
Main beam, 2b...Sub beam, 3...Power supply, 4...
...Beam splitter, 5...Shutter, 5a...
Opposite surface, 6... Absorber, 7... Output sensor, 10
...Switch, 11... Memory element, 22... Monostable multi, 32... OR circuit.

Claims (1)

[Claims] 1. A laser tube, a shutter that intermittently outputs a laser beam from the laser tube, an output sensor that detects the laser beam reflected by the shutter, and a storage means that stores the output value of the output sensor. What is claimed is: 1. A laser device comprising: a laser device for controlling a driving power source for a laser tube by switching outputs from the storage means and the output sensor according to opening/closing of a shutter; 2. A storage means is provided in the middle of the feedback means for controlling the laser tube based on the output value of the output sensor via a switching means that functions in conjunction with opening and closing of the shutter, and when the shutter is closed, the output sensor is connected to the laser tube. The output sensor is connected to a storage means to control the laser tube with the output value of the output sensor, and at the same time stores the output value in the storage means, and when the shutter is open, the storage means and the laser tube are connected and the information stored in the storage means is stored. 2. The laser device according to claim 1, wherein the switching means and the shutter are interlocked so as to control the laser tube based on the switching means. 3. The laser device according to claim 1, wherein the laser tube is configured to control the laser tube based on information from the storage means for a certain period of time after the shutter is closed.