JP2734945B2 - Laser oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser oscillator for oscillating a laser pulse train having a modulated pulse interval.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing an example of a conventional laser oscillator. In the figure, reference numeral 111 denotes a solid-state laser medium such as ruby, and an output mirror 112 and an end prism 113 as a total reflection mirror are arranged on both sides of the solid-state laser medium 111 to form an optical resonance unit. .

The light source means includes a flash lamp 114 for excitation and a high-voltage power supply 115 for applying a high voltage to the flash lamp. The high-voltage power supply 115 causes the flash lamp 114 to emit light, thereby causing the solid-state laser medium 111 to emit light. The laser light excited and stimulated emitted is resonated by the optical resonance means and oscillated from the output mirror 112.

The laser light thus oscillated is oscillated as a laser pulse train by the switching means. Specifically, an EO-Q switch 116, a Q-switch high-voltage power supply 117, and a control circuit 118 are provided as switching means. Then, the Q-switch high-voltage power supply 1
17, a timing pulse at a predetermined interval is input to the EO-Q switch 11 by the Q switch high voltage power supply 117.
6 are discretely opened and closed to form a laser pulse train in which giant pulses are oscillated at predetermined intervals, as shown in FIG.

As another example of a conventional laser oscillator, there is a technique described in Japanese Patent Application Laid-Open No. 61-84084.
This laser oscillator includes an acousto-optic Q switch disposed between a solid-state laser medium and a reflecting mirror constituting an optical resonance unit, a high-frequency driver, and a pulse signal control circuit. The high-frequency driver is controlled by a control signal from the controller, and the high-frequency driver controls the switching operation of the acousto-optic Q switch.

[0006]

However, in the conventional laser oscillator shown in FIG.
Since the O-Q switch 116 is used, a Q-switch high-voltage power supply 117 and a control circuit 118 for controlling the opening and closing of the EO-Q switch 116 are indispensable. Also,
In the laser oscillator described in Japanese Patent Application Laid-Open No. 61-84084, a high-frequency driver for operating an acousto-optic switch and a pulse signal control circuit for controlling the same are indispensable.

[0007] Therefore, any of the above-mentioned conventional laser oscillators requires a special device for operating the Q-switch, which causes a problem that the product cost of the laser oscillator is increased. Furthermore, E
Since the OQ switch 116 has a crystal structure,
It is necessary to precisely position the crystal axis of the OQ switch 116 with the optical axis of the laser and the crystal axis with the polarization of the laser. For this reason, since the positioning setting is complicated and difficult, there is a problem that an error easily occurs in the positioning setting and the reliability of the operation characteristics of the product is lacking.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a laser oscillator capable of reducing the size and cost of a product and having excellent operation reliability.

[0009]

In order to achieve the above objects, the present invention provides a solid-state laser medium and a flash for excitation.
Apply predetermined voltage to flash lamp and flash lamp
And a high voltage power supply, a light source means for a solid-state laser medium to excite generating a laser pulse train, the solid-state laser
-A resonated laser pulse train located on one side of the medium
Output mirror, and the output mirror
End prism located on the other side of solid-state laser medium
And an optical resonance means for resonating light emitted from the solid-state laser medium, and the end prism.
Light emitted from the solid state laser medium
Opaque when weaker than strength, stronger than above specified strength
Formed by saturable Q switch becomes transparent Itoki, <br/> switching means the solid-state laser light emitted from the medium is disposed in the optical resonator means for passing the light when the above predetermined intensity And passed the switching means
A photodetector that detects light and outputs a detection signal;
Of the light source means based on a detection signal from the photodetector of
A control circuit for controlling the operation timing, and a pulse train control means for controlling the operation timing of the light source means to change the interval between the laser pulse trains.

[0010]

According to the laser oscillator of the present invention, the pulse interval
Oscillator oscillating pulse train laser modulated
A solid-state laser medium as the switching means
Opaque when the light emitted from the
Saturable Q switch that becomes transparent when the
Since this switch is applied,
No high-voltage power supply or control circuit is required.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a laser oscillator according to one embodiment of the present invention.

The laser oscillator according to this embodiment includes a solid-state laser medium 1, a light source means 2 for exciting the solid-state laser medium 1 to generate a laser pulse train, and an optical resonance for resonating light emitted from the solid-state laser medium 1. Means 3, a switching means 4 disposed in the optical resonance means 3 for passing light emitted from the solid-state laser medium 1 when the light has a predetermined intensity, and a laser pulse train by controlling the operation timing of the light source means 2. And a pulse train control means 5 for changing the interval of.

The solid-state laser medium 1 is a medium that emits stimulated radiation, and is formed of, for example, ruby or the like.

The light source means 2 comprises a flash lamp 21 and a high-voltage power supply 22. Flash lamp 21
Emits light to the solid-state laser medium 1 and
Is a lamp for exciting. On the other hand, the high voltage power supply 22
Is a power supply for applying a desired voltage to the flash lamp 21.

The optical resonance means 3 is formed by an output mirror 31 and an end prism 32 disposed so as to sandwich the solid-state laser medium 1 from both sides. The end prism 32
This is a so-called total reflection mirror, and resonates light emitted from the solid-state laser medium 1 in cooperation with the output mirror 31.
The switching means 4 is provided between the end prism 32 and the solid-state laser medium 1.

The switching means 4 is a saturable switch, and is a saturable dye Q switch as a passive element.
Therefore, the saturable Q switch 4 can be formed at low cost. The saturable Q switch 4 becomes opaque when the light emitted from the solid-state laser medium 1 is weaker than a predetermined intensity, and becomes transparent when the light is stronger than the predetermined intensity. Therefore, if the saturable Q switch 4 is inserted between the solid-state laser medium 1 and the end prism 32 as a loss, the solid-state laser medium 1 is excited and emits light without the laser oscillator oscillating. Will start. Also, the saturable Q switch 4 is opaque and acts as a loss while the light emission of the solid-state laser medium 1 is small, but becomes transparent when the light emission of the solid-state laser medium 1 increases, ending the function as a loss and turning on. State. As a result, the laser light from the solid-state laser medium 1 passes through the saturable Q switch 4, and is resonated by the output mirror 31 and the end prism 32 of the optical resonance means 3 to generate a giant pulse as shown in FIG. It will be. Such a saturable Q switch 4 is controlled by the pulse train control means 5 via the light source means 2.

The pulse train control means 5 detects a laser beam that has passed through the saturable Q switch 4 and outputs a detection signal D, and based on the detection signal D from the photodetector 51, The control circuit 52 controls the operation timing of the high voltage power supply 22 by outputting the control signal C to the high voltage power supply 22. That is, since the saturable Q switch 4 is a passive element, it is necessary to control delicate timing of laser oscillation.

For this reason, the control circuit 52 includes the light detector 51
The control signal C indicating the timing of laser emission is input to the high-voltage power supply 22 based on the detection signal D from the controller, and feedback is performed so as to control the voltage of the high-voltage power supply 22 applied to the flash lamp 21. . Specifically, by controlling the voltage applied to the flash lamp 21, the amount of light that excites the solid-state laser medium 1 is controlled. Further, by controlling the amount of light of the solid-state laser medium 1, the timing at which the saturable Q switch 4, which is a passive element, changes from opaque to transparent is controlled. As a result, a laser pulse train PLS having a desired interval W can be output as shown in FIG.

Next, the operation of the laser oscillator of this embodiment will be described. When a voltage is applied to the flash lamp 21 from the high voltage power supply 22 of the light source means 2, the flash lamp 2
1 excites the solid-state laser medium 1 and emits light from the solid-state laser medium 1. When the voltage of the high-voltage power supply 22 is low, the stimulated emission of the solid-state laser medium 1 is small, and the amount of emitted light is small. Therefore, in this case, the saturable Q switch 4 is in an opaque state, and is in a so-called off state. When the stimulated emission from the solid-state laser medium 1 increases and the amount of light from the solid-state laser medium 1 increases, the saturable Q switch 4 operates to be turned on.

As a result, the solid state laser medium 1 is formed by the end prism 32 and the output mirror 31 of the optical resonance means 3.
Are emitted from the output mirror 31 and output as a laser pulse train PLS from the output mirror 31. That is, the solid-state laser medium 1 is excited by the excitation by the flash lamp 21, and after weak light is stimulated emitted from the solid-state laser medium 1 for a predetermined time, the stimulated emission from the solid-state laser medium 1 is increased and the intensity of the emitted light is increased. When the intensity becomes higher, the laser resonates by the optical resonance means 3 and the laser pulse train PLS is oscillated. By repeating such an operation, as shown in FIG. 2, a laser pulse train PLS having a pulse interval of a predetermined interval W is oscillated from this laser oscillator.

The laser pulse train PL thus oscillated
The control for maintaining or changing the interval W of S is performed by the pulse train control means 5. That is, the light that has passed through the saturable Q switch 4 is detected by the photodetector 51, and the control circuit 52 that has received the detection signal D outputs a control signal C indicating a desired pulse interval W to the high-voltage power supply 22. Thus, the intensity and the interval of the voltage of the high-voltage power supply 22 with respect to the flash lamp 21 are controlled, and the intensity and the interval of the light radiated from the solid-state laser medium 1 are controlled. That is, the amount of light radiated from the solid-state laser medium 1 is increased or decreased by controlling the high-voltage power supply 22, and the interval between the intensities is shortened or lengthened. The interval W of the laser pulse train PLS can be maintained and changed.

As described above, according to the laser oscillator of this embodiment, the inexpensive saturable Q switch 4 is used, and
Since the high-voltage power supply 117 for Q-switch operation and the special control circuit 118 which are indispensable for the above-mentioned conventional laser oscillator are not required, the cost of the laser oscillator product can be reduced. Further, since the saturable Q switch 4 does not require the positioning of the optical axis of the laser to be oscillated, the positioning of the polarization of the laser, and the like, there is no problem that an error occurs in the positioning setting. As a result, the reliability of the operation characteristics of the product can be maintained and improved.

[0023]

As described above, according to the laser oscillator of the present invention, the operation timing of the light source means is controlled by the pulse train control means, and the laser pulse train at a desired interval is oscillated by the light passage control of the switching means. Because of the structure, no device for operating the switching means is required. In particular, as switching means,
By applying an inexpensive saturable Q switch that becomes opaque when the light emitted from the solid-state laser medium is weaker than a predetermined intensity and becomes transparent when the light is stronger than a predetermined intensity, the Q indispensable to the above-described conventional laser oscillator can be obtained. Since a high-voltage power supply and a control circuit for switch operation are not required, the size of the product can be reduced and the cost of the product can be reduced.

Further, in the saturable Q switch, there is no need to position the crystal axis of the Q switch and the optical axis of the laser or to position the crystal axis and the polarization of the laser.
The problem that an error occurs in the positioning setting does not occur, and the reliability of the operation characteristics of the product can be maintained and improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a laser oscillator according to one embodiment of the present invention.

FIG. 2 is a graph showing an emitted laser pulse train.

FIG. 3 is a block diagram showing a laser oscillator according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solid-state laser medium 2 Light source means 3 Optical resonance means 4 Saturable Q switch 5 Pulse train control means 21 Flash lamp 22 High voltage power supply 31 Output mirror 32 End prism 51 Photodetector 52 Control circuit

Claims (1)

(57) [Claims] 1. A solid-state laser medium, a flash lamp for excitation, and a flash lamp
A high-voltage power supply for applying a voltage between the light source and the light source means for exciting the solid-state laser medium to generate a laser pulse train; and a resonant laser arranged on one side of the solid-state laser medium.
The output mirror that outputs the user pulse train and the output mirror
Oppositely disposed on the other side of the solid-state laser medium
An end resonating means for resonating light emitted from the solid-state laser medium , the solid-state laser disposed between the end prism;
-Opaque when the light emitted from the medium is weaker than the specified intensity
And becomes transparent when the strength is higher than the specified strength.
The light emitted from the solid-state laser medium is formed by a sum-Q switch, and passes the light when the light has a predetermined intensity or more.
A switching unit disposed in the optical resonance unit, and light passing through the switching unit is detected, and the detection is performed.
Photodetector that outputs an outgoing signal and detection from this photodetector
The operation timing of the light source means is controlled based on the signal.
And a that the control circuit controls the operation timing of the light source means, a laser oscillator, characterized in that a pulse train control means for changing the intervals of the laser pulse train.