Coherent light generators – Particular pumping means – Electrical
Patent
1987-09-28
1989-01-31
Sikes, William L.
Coherent light generators
Particular pumping means
Electrical
372 55, 372 56, 372 58, 372 61, H01S 3097, H01S 303
Patent
active
048021849
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a coaxial type CO.sub.2 laser which is adapted to be excited upon application of high frequency.
BACKGROUND OF THE INVENTION
A high frequency discharge excited CO.sub.2 laser has the following features:
(i) metallic electrodes and carbon dioxide gas (CO.sub.2) are not in contact with each other, so that no chemical reaction takes place therebetween;
(ii) being of capacitive ballast type, the laser has a high energy efficiency; and
(iii) since transverse electric discharge requires relatively low voltage, employment of a power source composed of a solid state device will do, so that the size of the equipment can be reduced.
For these reasons, the high frequency discharge excited CO.sub.2 laser can compose an oscillator which is
(i) small in size, and
(ii) high in efficiency.
However, transverse electric discharge is generaly used in the case of high frequency discharge excited and the resulting gain distribution over the cross section of laser tube does not have the circular symmetry. Accordingly, a high frequency discharge excited laser is used in combination with the transverse gas flow whose gain distribution similarly is not circular symmetry, wherefore a good beam mode is not to be expected. For this reason, a DC discharge excited coaxial type CO.sub.2 laser is used exclusively in the applications where good beam mode is a requirement. However, in respects other than beam mode, the DC discharge excited coaxial type laser is inferior to a high frequency discharge excited type laser.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a high frequency discharge excited coaxial type CO.sub.2 laser, which eliminates the disadvantages of the known art, and combines the advantages of a high frequency discharge excited type laser and those of a coaxial type laser, and therefore is able to produce a good beam mode.
In order to achieve the above-mentioned object, the present invention comprises a laser tube composed of a dielectric material. A CO.sub.2 laser gas is passed in the laser tube axially of the latter. Two helical electric conductors of the same pitch are affixed to the periphery of the laser tube, and a high frequency voltage is applied between the two helical electric conductors by means of a high frequency power source.
As described above, according to the present invention, the two helical electric conductors are affixed to the periphery of the laser tube composed of a dielectric material, and the high frequency voltage is applied between the two helical electric conductors by means of the high frequency power source to cause electric discharge between the two helical electric conductors in the laser tube; wherefore owing to the fact that the CO.sub.2 gas stream flowing in the laser tube possesses circular symmetry with respect to the axis of the laser tube, and the fact that the electric discharge occurs in a manner that it traces a helical locus gradually proceeding along and rotating about the axis of the laser tube because of the provision of the helical electric conductors, and hence the mode of the electric discharge becomes, as a whole, circular symmetry, it is possible to obtain the good beam mode which is proper to the coaxial type laser, without sacrificing the advantages of the high frequency discharge excited such as no chemical reaction taking place between the electrodes and the CO.sub.2 gas, high energy efficiency, utilization of a power source composed of a solid state device, and as a result CO.sub.2 laser for cutting can be made smaller in size and higher in efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view of an essential part of a high frequency discharge excited coaxial type laser according to an embodiment of the present invention; and
FIG. 2 is a cross-sectional view taken along line X--X of FIG. 1.
BEST MODE OF CARRYING OUT THE INVENTION
FIGS. 1 and 2 show the essential part of a high frequency discharge excited coaxial type laser according to an embodiment of the present inv
REFERENCES:
patent: 3386043 (1968-05-01), Marcatill et al.
patent: 3427567 (1969-02-01), Bridges et al.
Epps Georgia Y.
Fanuc Ltd
Sikes William L.
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