Coherent light generators – Particular resonant cavity – Folded cavity
Patent
1995-08-30
1997-01-21
Scott, Jr., Leon
Coherent light generators
Particular resonant cavity
Folded cavity
372 99, 372108, 372107, H01S 3081
Patent
active
055965946
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a laser oscillator installed in a laser beam machine.
BACKGROUND ART
A laser beam machine equipped with a laser oscillator is widely used as a machine tool for carrying out a machining operation, such as cutting or welding, on a workpiece made of metal or nonmetallic material. FIG. 1 is a perspective view schematically showing, by way of example, the arrangement of a laser beam machine which is generally indicated at 1. The laser beam machine 1 comprises a laser oscillator 2, a laser machine tool 3, and a numerical control device (NC device) 4. A laser beam output from the laser oscillator 2 is guided to the laser machine tool 3 through a shielding duct 5 serving as a light guide path and then reaches a machining head 6 of the laser machine tool 3.
The machining head 6 includes a converging lens for converging light which has been deflected downward by a deflecting mirror in the laser machine tool 3 after passing through the shielding duct 5. Vertical position of the machining head 6 can be controlled by a Z-axis mechanism, whereby the laser beam output from the machining head 6 is converged to a machining spot on a workpiece 7 placed on an X-Y table, the position of which is controlled by the numerical control device (NC device) 4. Usually, the laser beam converged to the machining spot is circularly polarized in order to ensure proper machining, and, therefore, it is desirable that when the laser beam is emitted from the laser oscillator 2, it has already been circularly polarized or linearly polarized at an angle of 45 degrees with respect to the horizontal plane. In the latter case, circularly polarized light can be obtained easily by arranging a phase delaying plate (1/4-wavelength plate) in the light path of the beam emitted from the laser oscillator 2, or by using a phase delaying mirror as the deflecting mirror in the laser machine tool 3.
The laser oscillator 2 is equipped with a gas excitation device including a discharge tube, and a laser resonator associated with a gas cooling unit etc. FIG. 2(a) through FIG. 2(c) schematically illustrate, by way of example, the arrangement of a conventionally employed laser resonator, along with additional elements such as a beam phase adjusting unit, wherein FIG. 2(a) is a plan view of parts of the laser resonator forming a resonant light path, as viewed from above a plane formed by the resonant light path, FIG. 2(b) is a front view of almost the entire laser resonator, as viewed from side with respect to the plane formed by the resonant light path, and FIG. 2(c) is a side view of the laser resonator, as viewed from the right-hand end face in FIG. 2(a).
Referring to these diagrams, a laser resonator, generally indicated at 8, comprises a machine frame 9, a gas excitation device 10, and a gas cooling unit 11. The machine frame 9 is composed of front and rear plates 12 and 13, each made of an aluminum plate, and four rods 14 connecting these plates so that the frame 9 may not be readily deformed by external force. Also, in order to minimize dimensional change of the machine frame 9 due to heat, each rod 14 is made of invar steel and is formed as a tubular member (resonator pipe), and cooling water is passed through the pipes 14 during operation of the laser resonator 8. That is, the machine frame 9 is designed so that thermal deformation thereof as a whole may be controlled to an extremely low level.
The gas excitation device 10 includes a discharge tube 15, a high-frequency power supply 16, an output mirror 17 arranged at a starting end (front plate 12) of the discharge tube 15, two bending mirrors 18, 18 arranged at an intermediate portion (rear plate 13) of the discharge tube 15, and a rear mirror 19 arranged at a terminal end (front plate 12) of the discharge tube 15. The gas excitation device 10 is fixed in position between the front and rear plates 12 and 13 via discharge tube holders 20. The bending mirrors 18, 18 are fitted in a reflector block 21 in such a manner that they face each other at an angle
REFERENCES:
patent: 4962506 (1990-10-01), Rahn et al.
patent: 4977574 (1990-12-01), Karube
patent: 5023886 (1991-06-01), Hobart et al.
patent: 5307367 (1994-04-01), Karube
patent: 5412685 (1995-05-01), Egawa et al.
Fanuc Ltd.
Jr. Leon Scott
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