JPS61128584A - Gas laser device - Google Patents

Abstract

PURPOSE:To form a gas laser device having excellent rise characteristics of a laser output and stability by shaping a Littrow prism to a shape that a projection to the surface vertical to an optical axis takes a circle. CONSTITUTION:A Littrow prism 20 is formed to a triangular columnar shape, a longitudinal section thereof has an obtuse angle, arranged onto an optical axis 5 so that an end surface 21 opposite to the obtuse angle is directd toward the laser tube 4 side and a circumferential surface 22 runs parallel with the optical axis 5, and shaped so that a projection to the surface vertical to the optical axis 5 takes a circle 23. The Littrow prism 20 can be manufactured simply with hgih precisionf by obliquely cutting a material such as a glass round bar having a required diameter at a predetermined angle. Accordingly, asymmetry to the optical axis 5 is made smaller than conventional Littrow prisms, and a gas laser device is hardly affected by the temperature change of the periphery, thus manufacturing the gas laser device, which has excellent rise characteristics of a laser output and from which the stable laser output is acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas laser device in which one of a pair of reflecting mirrors constituting an optical resonator is a retroprism.

[Technical background of the invention and its problems]

FIG. 5 shows an example of a monochromatic oscillation gas laser device.

This gas laser device consists of a laser tube (4) that has a cathode (2) at one end and an anode (3) at the other end so as not to interfere with the oscillation of laser light across the thin tube section (1). , and an optical resonator consisting of a pair of reflecting mirrors (6) (7) arranged on the optical axis (5) outside both ends of the laser tube (4). One reflecting mirror (6) of this optical resonator is an output mirror consisting of a concave mirror, and the other reflecting mirror (7)
The prism is composed of a litho prism having a dielectric multilayer film (9) that totally reflects the light incident on the prism (8).

Now, as shown in FIG. 6(A), the refractive index of the prism (8) is nl, and the refractive index of the surrounding air is no (where nl) < n
t).

The incident angle of the light (10) passing on the optical axis (5) is 00. When the refraction angle is 01, the light (10) passing on the optical axis (5) is incident on the prism (8) according to nl)sinθg=n1sinθ1, and the dielectric multilayer film (
After being reflected at 9), it travels in one direction to the output mirror through the re-string path. However, the refractive index of the optical glass used in this Retro prism differs slightly depending on the wavelength. A laser device that performs monochromatic oscillation can be obtained by separating the wavelengths of light.

However, the conventional retroprism is formed in a triangular shape with an apex angle of 906 as shown in FIG. Since the projection (11) on is formed in a rectangular shape,
When placed on the optical axis (5), it is extremely asymmetric with respect to the optical axis (5), is unstable against changes in ambient temperature such as radiant heat from the laser tube (4), and has special support methods. However, the structure of the mirror mount becomes complicated.

[Purpose of the invention]

The object of the present invention is to construct a monochromatic oscillation gas laser device that has good rise characteristics and can provide stable laser output.

[Summary of the invention]

One of the reflecting mirrors constituting the optical resonator disposed on the optical axis was composed of a retroprism, and the retroprism was formed so that its projection onto a plane perpendicular to the optical axis was circular.

[Embodiments of the invention]

Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

FIG. 1 shows the overall configuration of a monochromatic oscillation gas laser device.

This gas laser device differs from the gas laser device shown in FIG. However, since the other configurations are the same,
With respect to the configuration other than this Retroprism (20), the same parts are given the same numbers and detailed explanation thereof will be omitted.

The litroprism (20) is shown in FIGS. 2(A) and (
B) As shown in the figure, the longitudinal section is formed into a triangular cylindrical shape with an obtuse angle, the end surface (21) facing the obtuse angle faces the laser tube (4), and the peripheral surface (22) faces the laser tube (4). Axis (5
) is placed on the optical axis (5) so that it is parallel to the optical axis (5), and the projection onto a plane perpendicular to the axis (5) is circular (23) as shown in figure (C). . Note that the end surface (24) opposite to the end surface (21) on the side of the laser tube (4) is provided with a dielectric multilayer film (24) that totally reflects the light incident on the prism.
9) is provided.

This retroprism (20) can be manufactured easily and with high precision, for example, by diagonally cutting a glass round rod of a desired diameter at a predetermined angle.

When the retroprism (20) is formed as described above so that the projection onto the plane perpendicular to the optical axis (5) is circular,
Asymmetry with respect to the optical axis (5) is alleviated compared to conventional litro prisms, and there is less influence from ambient temperature changes.
It is possible to provide a gas laser device that has good laser output rise characteristics and can provide stable laser output.

In addition, this retroprism (20) has a circumferential surface with an optical axis (5
), the structure of the support can be simplified and its position can be adjusted with high precision.

Next, other embodiments will be described.

The above embodiments have described an external bell-shaped gas laser device in which the optical resonator is disposed outside the laser tube, but the present invention has the following features:
As shown in FIG. 3, the present invention can also be applied to an internal bell-shaped gas laser device in which retroprisms (20) are attached directly to both ends of the laser tube (4) so as to be in contact with the laser medium. In this case, especially if the outer diameter d1 of the end of the laser tube (4) and the diameter d2 of the retroprism (20) are matched, a more stable gas laser device can be obtained.

Furthermore, as shown in FIG. 4, a retroprism (20) is attached to the end of the laser tube (4), and these laser tubes (4)
By covering the end portion of the retroprism (20) with a cylinder (26) made of metal or the like with good thermal conductivity, a more stable gas laser device can be obtained.

[Purpose of the invention]

Since the lithoprism is formed in a shape in which the projection onto a plane perpendicular to the optical axis is circular, the asymmetry with respect to the optical axis is reduced compared to conventional lithoprisms, and it is less affected by environmental changes such as ambient temperature. , a gas laser device with excellent laser output rise characteristics and stability can be constructed.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the overall configuration of a gas laser device according to an embodiment of the present invention, and FIGS. 3 and 4 are views showing main parts of other embodiments of the present invention, respectively, and FIG. 5 is a view showing a conventional example. FIGS. 6A and 6B are a front view of a conventional retroprism and a projection view onto a plane perpendicular to the optical axis, respectively.

Claims (2)

[Claims] (1) One of the reflecting mirrors constituting the optical resonator arranged on the optical axis is composed of a retroprism, and this retroprism is formed in a shape whose projection onto a plane perpendicular to the optical axis forms a circle. Characteristic gas laser equipment. (2) The gas laser device according to claim 1, wherein the retroprism has a circumferential surface parallel to the optical axis.