JP2937441B2 - He-Ne gas laser device - Google Patents

Description

The present invention relates to a randomly polarized He—Ne gas laser device.

[Conventional technology]

Conventionally, in a randomly polarized He-Ne gas laser device, when there are a plurality of longitudinal modes in the output laser light, each longitudinal mode is linearly polarized, and two longitudinal modes are adjacent to each other.
Since the polarization directions of the two longitudinal modes are orthogonal to each other, the output laser light has only two polarization planes orthogonal to each other. The two orthogonal polarization directions of the laser light are:
It is arbitrary with respect to the optical axis of the laser light and is unique to each laser device. This is because the relative direction of the anisotropy of the pair of reflectors provided at the end portions of the laser tube is arbitrary, so that the laser device has anisotropic characteristics inherent to the device as a whole. This is because two anisotropic polarization directions of the oscillating laser light are determined by the anisotropic characteristics.

[Problems to be solved by the invention]

In the above-mentioned conventional randomly polarized He-Ne gas laser device, since the polarization direction is arbitrary with respect to the optical axis of the laser beam, the polarization direction of the laser beam may be mounted on a laser application device or the like via an optical system. For applications where is considered problematic, measure the polarization direction of each laser device, and when mounting,
An operation of rotating the laser device is required. Here, when the laser device has a factor whose characteristics are changed by rotation, for example, when the laser output is reduced because the thermal distribution is shifted from the optimal state, when mounting,
There is a disadvantage that rotating the laser device in a unique direction poses a problem in characteristics.

[Means for solving the problem]

In the randomly polarized He-Ne gas laser device according to the present invention, the directions exhibiting anisotropy of the pair of reflectors provided at both ends of the laser tube are defined with respect to the laser device, and are arranged so as to be orthogonal to each other. I have.

〔Example〕

Next, the present invention will be described with reference to the drawings. First
FIG. 1 is a sectional view showing a He—Ne gas laser device according to one embodiment of the present invention. In FIG. 1, an output side reflector 11 is formed by alternately laminating two kinds of dielectric material layers having different refractive indexes, has a transmittance of about 1%, and has a low melting glass And so on. Similarly, the total reflection side reflector 12 is sealed with a metal support part 22 having a metal exhaust pipe 3. The glass bulb 4 comprises a metal support part 21
And 22 are joined at both ends to form a laser tube, which has a glass tube 5 and an Al cathode 6 inside, and is filled with He and Ne.

FIGS. 2 (a) and 2 (b) show the directions of anisotropy in the mounted state of the two reflectors 11 and 12 in FIG. 1 (arrows in FIG. 2 (a)). Indicated by ) And the two orthogonal polarization directions (FIG. 2 (b)) of the oscillating laser light are schematically shown. FIG. 3 is a graph showing the anisotropy of the reflectors 11 and 12. FIG. 5 is a diagram showing an example of a method for measuring the direction of FIG.

In FIG. 3, the linearly polarized laser light is incident on the reflectors 11 and 12 almost perpendicularly, and the reflectors 11 and 12 are rotated. When the intensity of the reflected light is maximized, the polarization of the linearly polarized laser light is maximized. The direction is defined as the direction of the anisotropy of the reflectors 11 and 12, for example, the arrow Indicated by By arranging the two reflectors 11 and 12 so that their anisotropic directions (directions of arrows) are orthogonal to each other, as shown in FIG. As shown in FIG. 2B, anisotropy is obtained in two directions orthogonal to each other. In order to have a higher gain for the two polarization directions, the two oscillating two orthogonal, longitudinal mode polarization directions are more likely to oscillate in the two polarization directions. That is, the direction in which the two reflectors exhibit anisotropy is defined with respect to the laser tube or the laser device, and the reflectors are mounted so as to be perpendicular to each other, thereby oscillating perpendicularly to each other. Can be defined for the laser tube or the laser device.

〔The invention's effect〕

As described above, the present invention provides a randomly polarized He-Ne gas laser device, in which a direction exhibiting anisotropy of a pair of reflectors is defined with respect to the gas laser device, and arranged so as to be orthogonal to each other. This has the effect that the polarization direction of the gas laser device can be stably defined in a specific direction. That is, when a plurality of longitudinal modes are oscillating, the polarization planes of the longitudinal modes adjacent to each other are orthogonal to each other, so that the laser output light has no plane of polarization. , But only two planes of polarization orthogonal to each other. How many times this plane of polarization is in relation to the horizontal and vertical planes is completely random with respect to the individual laser device. In the process leading to laser oscillation due to reflection and amplification of the laser beam, only the longitudinal mode in the polarization direction in which oscillation is most likely to occur is selectively oscillated. The polarization direction in which oscillation is most likely to occur is determined by the direction of the laser tube, sealing gas, mirror, discharge, etc., which contributes to laser oscillation. In particular, the contribution of the anisotropy of the mirror, which causes a directional variation in the manufacturing process of the laser device, is large, and the polarization plane of the laser is substantially determined by the anisotropy of the mirror. When the anisotropy of the two opposing mirrors is in any direction with respect to each other and is also in any direction with respect to the laser device, the polarization plane of the laser beam is changed to a certain reference plane ( For example, it is unclear how many times the base is tilted. In addition, if the anisotropic directions of the pair of mirrors are not orthogonal to each other but in any direction, the longitudinal mode having one polarization plane among the longitudinal modes in which the polarization planes of the laser light are orthogonal to each other. Since the gain is high and the gain of the longitudinal mode having a plane of polarization orthogonal to this is low, the output becomes unstable. However, in the present invention, the anisotropy of two opposing mirrors is arranged so as to be orthogonal to each other, and the direction of the anisotropy of the mirror is set to a specific direction with respect to the laser device. Since the two orthogonal directions in which the internal oscillation is apt to occur are defined, the polarization plane of the laser light can be defined in a specific direction with respect to the laser device. Further, in the present invention, since the anisotropic directions of the pair of mirrors are orthogonal to each other, the gain for the longitudinal mode in which the polarization planes are orthogonal to each other is the same for the longitudinal mode of either polarization plane, A stable output is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment according to the present invention, FIG. 2 is a diagram schematically showing the relationship between the anisotropic direction of a pair of reflectors and the polarization direction of oscillating laser light, The figure shows an example of a method for measuring the direction of the anisotropy of the reflector. 11 ... Reflector on output side, 12 ... Reflector on total reflection side, 21,22 ...
... Metal support parts, 3 ... Metal exhaust pipe, 4 ... Glass bulb, 5 ... Glass thin tube, 6 ... Al cathode.

Claims (1)

(57) [Claims] 1. A laser tube having electrodes and a laser gas sealed therein is made of a dielectric multilayer film comprising a large number of two types of dielectric material layers having different refractive indices alternately provided, and has a reflection characteristic having anisotropy. In the He-Ne gas laser device provided between the pair of reflectors shown, the two reflectors have anisotropic directions defined with respect to the laser device, and are arranged so as to be orthogonal to each other. He-Ne gas laser device characterized by the above-mentioned.