Coherent light generators – Particular beam control device – Optical output stabilization
Reexamination Certificate
1999-12-17
2001-12-11
Arroyo, Teresa M. (Department: 2881)
Coherent light generators
Particular beam control device
Optical output stabilization
C372S029010, C372S029011, C372S029012, C372S029015, C372S038010, C372S038040
Reexamination Certificate
active
06330258
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a laser apparatus, and more particularly to a solid-state laser apparatus using a lamp as laser excitation means, for providing iterative oscillatory outputs of pulsed laser beams.
2. Description of the Related Art
This type of solid-state laser apparatus typically allows a minute standby discharge current, a so-called simmer current, to flow through the excitation lamp during the standby periods (not oscillating laser) for the purpose of achieving an improved start of lighting of the excitation lamp upon the laser oscillation. The simmer current forms a discharge path within the excitation lamp despite the standby periods, so that an intrinsic lamp current for the lamp lighting (laser oscillation) can readily flow therethrough from the main laser power supply, making high-speed iterative pulse oscillations feasible.
As a result of investigations effected by the inventor, it has proved that upon the iterative oscillatory outputs of the pulsed laser beams, the simmer current may affect both the service life of the excitation lamp and the stability in the laser output. That is, it has turned out that a larger simmer current gives the excitation lamp a shorter service life, whereas a smaller simmer current renders the laser output more unstable upon the high-speed iterations.
Such a conventional solid-state laser apparatus has however employed the simmer current having a fixed current value irrespective of the repetition rate of the pulse oscillations. For this reason, there arose problems on occasions that the excitation lamp may become consumed at a relatively early stage even in the case of low pulse repetition rate operations at all times or of low ordinary operation rate or that the laser output may become unstable upon an increase in the pulse repetition rate.
SUMMARY OF THE INVENTION
The present invention was conceived in view of the above problems. It is therefore the object of the present invention to provide a laser apparatus designed to extend the service life of its excitation lamp as far as possible and to improve the stability in its laser output, through the proper control of the current value of the simmer current.
In order to attain the above object, according to a first aspect of the present invention there is provided a laser apparatus having an excitation lamp through which a simmer current flows during the standby period and into which a pulsed lamp current is fed upon the laser oscillation to cause a pulse lighting of the excitation lamp, whose optical energy excites a solid-state laser medium to provide an oscillatory output of pulsed laser beams, the apparatus comprising means for variably controlling the current value of the simmer current in conformity with the repetition rate or the pulse separation of the pulsed laser beams.
According to a second aspect of the present invention there is provided a laser apparatus having an excitation lamp through which a simmer current flows during the standby period and into which a pulsed lamp current is fed upon the laser oscillation to cause a pulse lighting of the excitation lamp, whose optical energy excites a solid-state laser medium to provide an oscillatory output of pulsed laser beams, the apparatus comprising zone setting means for setting a plurality of zones of the repetition rate or the pulse separation of the pulsed laser beams; simmer current setting means for separately setting the current value of the simmer current for each of the plurality of zones; zone judgment means for judging zones associated with the pulsed laser beams output in an oscillatory manner; and simmer current control means for controlling the simmer current to have current values corresponding to associated zones judged by the zone judgment means.
The zone judgment means may include means for judging the associated zones on the basis of a sequence previously defined for the oscillatory output of the pulsed laser beams.
Alternatively, the zone judgment means may include measurement means for measuring the repetition rate or the pulse separation of the pulsed laser beams oscillatorily output in response to predetermined external signals issued at any arbitrary timings; and means for judging the associated zones on the basis of measured values acquired by the measurement means.
The simmer current control means preferably comprise a simmer power supply circuit including a switching element, for the supply of the simmer current to the excitation lamp; simmer current detection means for detecting the simmer current to issue a voltage signal indicative of the current value thereof; an amplifier capable of selecting any one of a plurality of amplification factors defined in a corresponding manner for each of the plurality of zones, the amplifier amplifying the voltage signal from the current detection means with selected one of the amplification factors; amplification factor switching means for switching the amplifier to have the amplification factor corresponding to an associated zone judged by the zone judgment means; and pulse width control means for comparing an output signal from the amplifier with a previously defined reference current value and for providing a switching control of the switching element by use of switching pulses of a certain frequency having such a pulse width as to allow the comparison error to approach zero.
According to the laser apparatus of the present invention, as set forth hereinabove, it is possible to ensure as long a service life of the excitation lamp as possible and to achieve an improved stability of the laser output by providing a variable control of the current values of the simmer current in conformity with the pulse repetition rate of the pulsed laser beams.
REFERENCES:
patent: 4829530 (1989-05-01), Sato et al.
patent: 5017834 (1991-05-01), Farnsworth
patent: 5191261 (1993-03-01), Mass
patent: 5692004 (1997-11-01), Greene
Arroyo Teresa M.
Menefee James
Miyachi Technos Corporation
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Laser apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Laser apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Laser apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2583179