JPS6348875A - Laser oscillator - Google Patents

Abstract

PURPOSE:To suppress the deterioration of oscillating characteristics accompanging the change in ambient temperature to a large extent and to improve reliability, by forming a pair of optical substrate, which support both reflecting mirrors, with Ni cast iron having a small thermal expansion coefficient. CONSTITUTION:In the Table, the thermal expansion coefficients of materials (a), which constitute a pair of optical substrate 6, are compared. Among the materials, the thermal expansion coefficient of Ni cast iron (b) has the smallest value. Above all, the thermal expansion coefficient of high Ni cast iron, which includes 30 wt % or more Ni, is about 1/3-1/4 those of gray cast iron (c) and steels for general structures. Therefore, each optical substrate is formed with the high Ni cast iron having the small thermal expansion coefficient. In a laser oscillator constituted in this way, the thermal expansion of the optical substrate 6 is very small even if ambient temperature of the optical substrate is changed by the output of laser beam. A resonator can be maintained stably. Thus, the deterioration in oscillating characteristics accompanying the change in ambient temperature is largely suppressed, and the highly reliable laser oscillator is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is characterized in that the opposing directions of a pair of electrodes, the flow direction of laser gas flowing between them, and the opposing directions of a total reflection mirror and a partial reflection mirror are respectively perpendicular to each other. The present invention relates to an improvement of an optical substrate that supports a triaxial orthogonal laser oscillator, particularly a total reflection mirror and a partial reflection mirror.

[Conventional technology]

Figures 2 and 3 show a conventional three-axis orthogonal laser oscillator. A discharge (3) occurs between a pair of electrodes placed opposite each other. (4) The laser gas is circulated within the housing (1) and both the electrodes (2) are
), a blower that flows laser gas between them, (5) three support shafts penetrating the end of the housing (1), and (8) facing each other supported by both ends of each support shaft (5). a pair of optical substrates, (7) is a mirror holder attached to each optical substrate (8), and (8) is one mirror holder (7).
(9) is a total reflection mirror attached to the other mirror holder (7), (10) is the mirror holder (7) portion of each optical board (6) and the housing (1) These bellows are connected to the side walls of each.

A conventional laser oscillator is configured as described above, with a blower (
4) starts, the laser gas circulates inside the housing (1),
It flows between the pair of electrodes (2) in a direction perpendicular to the opposing direction. The waves generated near one of the reflecting mirrors (8) or (9) pass between the two electrodes (2) and return to the two reflecting mirrors (8).
, (9), it is amplified while repeating the incoming reflection, and the partial reflecting mirror (
8) is output as a laser beam.

By the way, the laser gas circulating in the housing (1) is low temperature at the entrance side of the pair of electrodes (2) and high temperature at the exit side, so the housing (1) thermally expands unevenly and distortion occurs. Furthermore, when exchanging the laser gas, the gas is filled in after the inside of the housing (1) is evacuated, so the housing (1) is deformed at this time, and the reflecting mirror (8) is directly attached to the housing (1). (9), if provided, bidirectional mirror (8).

(9) is misaligned, and the oscillation characteristics are significantly degraded.

Therefore, conventionally, a mirror holder (7) is provided on the optical board (8), and each of the reflecting mirrors (8) and (9) is floated from the housing (1) by a support shaft (5). A method is adopted in which (ΔX) is made as low as possible by forming it from a low expansion alloy steel such as invar.

[Problem that the invention seeks to solve]

In the conventional laser oscillator like the one above, the mirror holder (
Since the optical substrate (6) to which 7) is attached is made of gray cast iron or general structural steel, when the temperature rises (ΔL1) as shown in FIG.

As shown by (ΔL2), the optical board (6) thermally expands, and as a result, the pitch between the housing (1) and the support shaft (5) also shifts, and the opposing optical board (6) and housing (1) ) and not only cannot absorb (ΔX), but also the pitches of (L+) and (L2) shift as well, causing the alignment of both mirrors (8) and (9) to shift. There was a problem in that the oscillation characteristics deteriorated significantly.

This invention was made to solve this problem, and the object is to obtain a laser oscillator that can eliminate misalignment of both mirrors and suppress deterioration of oscillation characteristics even when the ambient temperature changes. do.

[Means for solving problems]

In the laser oscillator according to the present invention, each of the pair of optical substrates that respectively support the mirrors is made of Ni cast iron having a small coefficient of thermal expansion.

[Effect]

In this invention, each optical substrate is made of Ni cast iron, which has a smaller coefficient of thermal expansion than conventional gray cast iron or general structural steel, so the alignment of both mirrors can be maintained even when the ambient temperature changes. As a result, the deviation of the oscillation characteristics is reduced, and deterioration of oscillation characteristics can be suppressed.

〔Example〕

FIG. 1 shows an embodiment of the present invention, and shows a comparison of the coefficients of thermal expansion of the materials constituting the pair of optical substrates (6). As is clear from Figure 1, Ni cast iron has the lowest coefficient of thermal expansion among all materials, and among these, high NIPI iron containing 30% by weight or more of Ni has a higher coefficient of thermal expansion than gray cast iron or general structural steel. , the thermal expansion coefficient is approx. In this embodiment, each optical substrate (6) is made of high N1Fl iron with a small coefficient of thermal expansion.

Note that, except for the material of each optical substrate (6), the structure is exactly the same as that of the conventional laser oscillator shown in FIGS. 2 and 3.

In the laser oscillator configured as described above, even if the ambient temperature of each optical substrate (6) changes due to the output of laser light, the thermal expansion (ΔL+) of the optical substrate (8) shown in FIG.
, (ΔL2) are significantly reduced, making it possible to stably hold the resonator. Therefore, a decrease in oscillation characteristics due to changes in ambient temperature is significantly suppressed, and a highly reliable laser oscillator can be obtained.

In addition, in the above embodiment, a case was shown in which high Ni cast iron was used as the material for each of the pair of optical substrates (8), but even if N1pF iron with a Ni content of less than 30% by weight is used, gray cast iron or Since it has a smaller coefficient of thermal expansion than general structural steel, it can be used satisfactorily as a material for the optical substrate (6).

〔Effect of the invention〕

As explained above, this invention uses a pair of optical substrates each supporting one reflecting mirror as an N1P substrate having a small coefficient of thermal expansion.
Since it is made of iron, there is less misalignment of both mirrors even when the ambient temperature changes, and the deterioration of oscillation characteristics due to changes in the surrounding temperature is greatly suppressed, increasing reliability. It has effects such as being able to improve sexual performance.

[Brief explanation of the drawing]

FIG. 1 is a comparison of thermal expansion coefficients of optical substrate materials showing one embodiment of the present invention, FIG. 2 is a front sectional view showing a conventional laser oscillator, and FIG. 3 is a right side view of FIG. 2. (1)...Case, (2)...Electrode, (3)...
...discharge, (4) blower, (5) ... support shaft, (6) ... optical board, (8) ... partial reflection mirror, (9) ... total reflection mirror, (10) ...bellows. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A blower that circulates laser gas within the housing, a pair of electrodes that generate electric discharge, a pair of optical boards that are placed facing each other on the outside of the housing via a support shaft, and each optical board that is attached to the a fully reflecting mirror and a partially reflecting mirror that face each other;
1. A laser oscillator comprising bellows that respectively connect the reflecting mirror mounting portion of each optical substrate and a side wall of a housing, and each of the optical substrates is made of Ni cast iron. (2) The laser oscillator according to claim 1, wherein the Ni cast iron used for the optical substrate is high Ni cast iron containing 30% by weight or more of Ni.