Coherent light generators – Particular component circuitry – Optical pumping
Reexamination Certificate
1998-07-21
2001-04-24
Font, Frank G. (Department: 2877)
Coherent light generators
Particular component circuitry
Optical pumping
C372S028000, C372S081000, C363S065000, C363S165000
Reexamination Certificate
active
06222862
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a control method of exciting a pulse laser and a power supply unit for exciting a pulse laser, and more particularly to a control method of exciting a pulse laser as well as to a power supply unit for exciting a pulse laser for a laser unit for exciting a laser medium by, any exciting unit such as electric discharge, a lamp or a laser diode and emitting a laser beam.
BACKGROUND OF THE INVENTION
FIG. 16
shows a laser diode-excited solid laser unit based on a conventional type of power supply unit for laser excitation. A power supply unit
100
for laser excitation outputs a current having a current value set by a current setting device
102
to a laser diode
106
as an exciting unit in synchronism with a reference pulse signal (laser power output signal) outputted from a reference oscillator
104
.
The laser diode
106
outputs excitation light by energization and excites a solid laser medium
108
comprising a YAG rod or the like, and the solid laser medium
108
outputs a laser in a pulse form from an optical resonator
116
comprising a total reflection mirror
112
provided in the rear side thereof and a half reflection mirror
114
provided in the front side (output side) thereof.
FIG. 17A
to
FIG. 17C
show a power output waveform and a laser output waveform according to the conventional type of power supply unit shown in FIG.
16
.
FIG. 17A
shows a power output waveform when a current set value PI by the current setting device
102
is low, and
FIG. 17B
shows a power output waveform when the current set value PI by the current setting device
102
is high respectively, while a reference sign La in
FIG. 17C
shows a laser output waveform when the current set value PI is low, and a reference sign Lb therein shows a laser output waveform when the current set value PI is high respectively.
A power output waveform in the conventional type of power supply unit for laser excitation is, as shown in
FIGS. 17A and 17B
, a simple rectangular waveform regardless of amplitude of current set value PI is constant at one pulse.
As the conventional type of power supply unit for laser excitation outputs a current as a pulse with one simple rectangular waveform (constant current set value at one pulse), if the current set value PI is low, laser output becomes as indicated by the reference sign La in
FIG. 17C
, which shows that the delay Da in rising of the laser output to power output (laser output signal) is larger, so that 50 to 70 &mgr;s is required for laser output.
This delay becomes smaller, by making a current set value higher, according to the set value, but even if the value is set to a quite high current value (twice to three times), the delay Db can not be reduced to not more than 20 to 30 &mgr;s in the laser output as indicated by the reference sign Lb in FIG.
17
C.
Regardless of the current set value, rise times Ta, Tb required for laser output to reach its stable state increase, as shown in
FIG. 17C
, with a first order lag therebetween and a time of 100 to 200 &mgr;s has to be required.
When pulse laser output is used for laser machining, and if a pulse frequency is specified to be 1 kHz and a duty to be 10% as typical machining conditions, a pulse width is 100 &mgr;s, which corresponds to a time t in FIG.
17
C. Under the machining conditions, when the current set value PI is low, the laser output La can hardly be effected, and even when the current set value PI is high, the laser output Lb in its stable state can not be effected, in which the output waveform is a waveform like a chopping wave. For this reason, if the pulse frequency is set to be high and the duty is set to be low in the conventional type of power supply unit, characteristics in machining such as cutting are degraded.
As described above, the conventional type of power supply unit for laser excitation has had such problems that quick response of laser output can not be made, so that an accurate pulse laser can not be outputted when machining is carried out with short pulses.
SUMMARY OF THE INVENTION
It is an object of the present invention to obtain, for the purpose of solving the problems described above, a control method of exciting a pulse laser and a power supply unit for exciting a pulse laser in which there is no delay in rising of a laser output to a laser power output signal, the laser output rapidly reaches its stationary output, and responsiveness of pulse output is improved.
With the control method of exciting a pulse laser according to the present invention, there are steps of exciting an exciting unit with a first excitation amplitude immediately before a laser output signal is turned ON and until the laser output signal is turned ON, exciting the exciting unit with a second excitation amplitude from a point of time immediately after the laser output signal is turned ON until a specified point of time before the laser output signal is turned OFF, and exciting the exciting unit with a third excitation amplitude from a point of time when energization according to the second excitation amplitude is ended until the laser output signal is turned OFF, so that a delay in a rising portion of laser output can be zero or extremely short period, the laser output can rapidly reach its stationary output, and responsiveness of pulse output is improved, and for this reason machining at a high frequency and a low duty which used to be incapable of performance in the conventional type of power unit can be effected.
With the power supply unit for exciting a pulse laser according to the present invention, a first power unit operates between a point in time when a reference pulse signal changes state, until receipt of a first time delay signal having a time delay with respect to the reference pulse signal, a second power unit operates from receipt of the first time delay signal until receipt of a second time delay signal having a time delay with respect to the first time delay signal, and a third power unit operates from receipt of the second time delay signal until falling of the first time delay signal, and output by synthesizing output from the first power unit, second power unit and the third power unit is supplied to an exciting unit, so that a delay in a rising portion of laser output can be zero or an extremely short period, the laser output can rapidly reach its stationary output, and responsiveness of pulse output is improved, and for this reason machining at a high frequency and a low duty which used to be incapable of performance in the conventional type of power unit can be effected.
Other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.
REFERENCES:
patent: 5740023 (1998-04-01), Brooke et al.
patent: 5883797 (1999-03-01), Amaro et al.
patent: 5946206 (1999-08-01), Shimizu et al.
patent: 6088248 (2000-07-01), Schenk et al.
patent: 6091749 (2000-07-01), Hoffmaster et al.
patent: 3014220 (1980-04-01), None
patent: 30-14220 (1980-10-01), None
patent: 32-16186 (1982-11-01), None
patent: 0716485 (1995-11-01), None
patent: 1-93188 (1989-04-01), None
patent: 7-44039 (1995-10-01), None
patent: 11135870 (1997-10-01), None
Kinbara Yoshihide
Sato Shinji
Font Frank G.
Mitsubishi Denki & Kabushiki Kaisha
Rodriguez Armando
Sughrue Mion Zinn Macpeak & Seas, PLLC
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