JPS62205676A - Laser device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to improvements in laser technology. More particularly, the present invention relates to lasers including improved electrodes and methods for attaching the same to laser substrates.

BACKGROUND OF THE INVENTION In a laser process, a laser 'N, an anode and a cathode, interact to create a current flow in the laser gas. This current excites the gas to the high energy state required for laser operation.

These polarizations are located near the ends of channels within the laser body containing suitable gases, including, for example, helium and neon.

The cathode is usually a dome-shaped metal structure,
The metal anode can take various shapes, such as a dome or a disk. Its operation is less sensitive to shape than the cathode. In operation, the cathode is maintained at a negative potential and acts as a gas emitter, and the anode is maintained at a positively charged helium-neon ion potential and acts as a gas collector.

For example, in a laser-applied device such as a ring laser gyroscope, well-polished mirrors are placed at both ends of the laser body. When such a laser is used as one element of the device, only relatively small variations in the distance between the mirrors are tolerated. This is because this distance is important for the laser output. Maintaining a given distance within tolerances poses difficult technical problems when lasers are operated in relatively extreme temperature environments. To overcome this problem, laser bodies are commonly made of very low thermal coefficient materials, including various glass ceramics, such as those sold under the trademarks Zer, odur, or Cer-Vit. On the other hand, the cathode and anode are made of metal conductors to allow current to flow through the laser gas.

Currently, metal or metal alloy laser electrodes are made in many ways, such as stamping and machining. Such methods require extensive internal surface cleaning and preparation.

Furthermore, in some applications the electrode must be sealed to the laser body. Therefore, a glass-to-metal seal is usually attached to the laser substrate. This is done according to different compositions of the L poles. Indium is commonly used as a sealant.

Such an indium seal is described in U.S. Patent 4,273,2
No. 82 (Novell, et al.) "Glass or Ceramic-Metal Seals".

The metal alloy electrode provides an electrical contact from the outside of the laser to the inside, and thus a means for passing the current for laser operation, but the degree of expansion it undergoes due to thermal stress is limited when the laser operation is short-term. However, it does affect the integrity of the device over a long period of time. The large mismatch in thermal expansion coefficients between the metal electrodes and the glass-ceramic laser substrate introduces significant stress into the device. For example, the mismatch in thermal expansion coefficients of aluminum and ZerodurO limits the average life of the seal between the electrode and the laser body, given cycling between, for example, -55°C and 125°C. And aluminum-glass seals that typically contain indium are limited by the indium melting point of 156°C.

Stresses introduced into a thermally stressed system containing a glass-ceramic laser substrate coupled to a metal electrode cause a small amount of laser substrate distortion. This distortion or bending strongly affects the performance characteristics of the laser in applications such as ring laser gyroscopes. In addition to physical strain, relative movement of the indium sealant and current at the laser body-electrode interface will ultimately lead to seal failure. Although "hard" glass seals exist, they are inadequate due to stress-induced differential thermal expansion. Such stress actually affects the glass laser substrate,
It can also cause it to explode.

The above-mentioned problems may limit the effectiveness of lasers and suitable manufacturing methods for applications such as ring laser gyroscopes, where the absence of contamination is important for proper manufacturing quality and device performance. interact. In the manufacture of such precision devices, heating is commonly used to dissipate volatile materials such as water, alcohol and plastics.

During assembly of the ring laser gyro device, including the laser body, mirrors and electrodes, the device is placed on a stand and baked to dissipate unwanted contaminants. This baking process and the resulting laser cleanliness level is 1.
Limited by a melting point of 56°C. (Otherwise, the assembly could be baked at temperatures as high as about 100°C, limited by the tolerances of the mirrors in the assembly.) Therefore, in addition to the detrimental effects of thermal application undistortion, Conventional laser assemblies that include metal electrodes with mismatched coefficients of thermal expansion and ceramic dielectric laser bodies joined by indium seals have limited operational performance and ease of manufacture.

SUMMARY OF THE INVENTION The present invention provides improvements to lasers of the type that include a dielectric or insulating substrate of material of given thermal expansion properties and at least one electrode affixed thereto, thereby overcoming the aforementioned deficiencies of the prior art. The improvement includes an electrode made of a cemented material or an insulating material with thermal expansion properties closely matched to the laser substrate, and the electrode is a dielectric or an insulator that provides an electric field support (field) to the laser substrate.

assisted) method.

The present invention also provides an improved method of manufacturing a ring laser gyroscope. The improved method includes assembling a laser electrode that is part of a dielectric or insulating material that has thermal expansion properties that closely match the laser substrate. The electrode is then attached to the laser body with electric field assistance (field assist method).
It is layered with Finally, the substrate is baked at a temperature above 156° C. with the electrodes fixed thereto.

Description of examples A side cross-section of a laser 10 according to the invention is shown in the figure.

Laser 10 is preferably Cer-Vit or Zerod.
It includes a laser body 12 formed from a ceramic glass such as UR. The laser cavity 14 is located within the laser body 12 with highly polished mirrors 16,18 at each end.

Anode 20 and cathode 22 communicate by upwardly directed holes 24 and 26 leading to laser cavity 14 .

The cathode 22 is generally hemispherical and consists of an outer shell 28 of glass, bath-fused silica, or glass ceramic, which has a thin film layer 3 of aluminum or aluminum alloy on its inner surface.
have. Shell 28 may be made by several known glass or crystal forming techniques, such as glass blowing and molding techniques. Further, the shell 28 is made of, for example, Zerod.
It can be machined from a glass-ceramic, such as doped glass known under the trademark ULE, Car-Vit or ULE. Suitable techniques for coating the inner surface of shell 28 to form layer 30 include direct air deposition, sputtering, or ion blating of aluminum or aluminum alloys. The two sides of the anode 20 have almost the same structure. In the example of the anode, copper or a copper alloy may form the thin film layer. many other metals, nickel, chromium,
Iron, titanium, tungsten, aluminum, gold, etc. are applicable.

The inventors have discovered that by employing an electrode that includes a shell with a coefficient of thermal expansion that closely matches that of the laser body 12, the stresses acting on the seal that secures the polarization to the laser body are significantly reduced. It has been found that both the performance and lifetime of the laser are improved as a result.

Additionally, a suitable metal film does not have a mass that would impose significant stress on the seal, so as long as the metal layer is thick enough to provide uniform conductivity to the electrode, the performance of the electrode will be similar to that of the metal or It has been found that the electrode is sufficiently equivalent to that of an electrode made only of a metal alloy.

Seal 32 is, in this example, a Mallor
It is made using an electric field assisted adhesion method known as the y) method. In such a method, the glass '4 pole and the laser body are connected to a
It is heated to a temperature of 00°C. As the assembly is heated, its electrical conductivity increases, allowing 'it current to flow through the electrode-laser body interface. The electric current causes a wavenumber of metal to pass from the thin film layer to the glass. As a result, a strong permanent bond is formed that is not subject to certain failure modes that characterize conventional glass-gold #i bonds, such as those resulting from the melting temperature of indium.

Laser base 12. The closely matched thermal properties of the anode 20 and cathode 22 enable the electric field assisted bonding process. The process results in significantly improved bond strength (several thousand p,s,i, vs. hundreds of p,s,i, for indium seals). As mentioned earlier,
The high strength of such bonds can allow the transfer of destructive thermal stresses between laser substrates and electrodes of different thermal properties.

When closely aligned laser substrates and electrodes are joined by field-assisted adhesion, the assembly in the example of a ring laser gyroscope is produced by a very advantageous manufacturing method that significantly improves the quality and performance of the device. It can be said that there are. Removal of the constraints due to thermal expansion discontinuity and the relatively low melting point of the indium seal requires that the assembly containing the welded electrodes be baked in a low pressure environment at a temperature approximately 100° C. above the melting point temperature of indium. is allowed. (In the example of a ring laser gyroscope, the baking of the device would be limited to about 250°C by the mirrors in the assembly, but it would be about 150°C.
It is about 100c higher than the melting point of indium at °C. ) A very desirable result of this increased bake temperature is its effectiveness in an open air environment. A 100° C. increase in bake temperature increases the metal vaporization pressure by more than 20, ie, more than 100 times. Since the cleanliness of an assembly is a function of the difference between the evaporation pressure and the ambient environmental pressure, to obtain a given level of cleanliness
This means that only +1 suction time is required.

As a result, the manufacturing cost of the laser according to the invention is lower and its performance, quality and useful life are increased.

Accordingly, an improved method and apparatus is provided to the laser manufacturing art by the present invention. By employing the teachings of the present invention, laser devices can be made that have increased durability for use in thermal environments that degrade device performance. Furthermore, advantageous adhesive edges not applicable in the prior art may be used in accordance with the teachings of the present invention.

In combination with the structure of the laser electrode, such a bonding method provides a high quality laser assembly with low manufacturing costs.

[Brief explanation of drawings]

The drawing is a cross-sectional view of a laser device according to the invention. [Explanation of symbols of main parts] 12・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・Base 20・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・Anode 22...
・・・・・・・・・・・・・・・・・・・・・・・・
... Cando P Zokune City 1 [Mi,! (Method) 11/(6JJ 11 of 1961), 1 Mr. Michibu Uga, Commissioner of the Office of Special Correction■ ・Table of 1 ¥ Small Patent Application No. 44319 of 1988 2 Name of Invention Laser Device 3? ! Relationship with 1tdi1: Patent applicant name: Lydon Systems, Inc. Name of attorney (6444): Patent attorney Okabe
II Mi Husband' (1) Please submit one copy of the power of attorney and one copy of the translation as shown in the attached sheet. (2) Correction application form 1 that accurately describes the 9 representatives as shown in the attached sheet
I will submit the notification. (3) Please submit one printable statement as shown in the attached sheet. (4) We will submit one official drawing as shown in the attached sheet.

Claims (1)

[Claims] 1. A laser device comprising a dielectric or insulating substrate of a material with given thermal expansion properties and at least one electrode attached to the substrate, comprising: a) the at least one electrode is attached to the substrate; and b) the at least one electrode is field-assisted bonded to the dielectric or insulator substrate. 2. The laser device according to claim 1, wherein the electrode further includes a metal coating. 3. In the laser device according to claim 2, a) the electrode has a hollow substantially semicircular shape, and b) the metal coating is provided on the inner surface of the substantially semispherical shape. laser equipment. 4. A laser device according to claim 3, wherein the at least one electrode is a cathode. 5. A laser device according to claim 4, wherein the at least one electrode additionally comprises at least one anode. 6. A method of manufacturing a ring laser gyroscope comprising the steps of: providing a laser substrate of a material with given thermal expansion properties and attaching at least one electrode to the substrate; a) thermal expansion closely matched to the substrate; b) field-assisted bonding of the electrode to the substrate; and c) attachment of the substrate to the substrate at a temperature of 156° C. or higher. A method consisting of a step of baking together with the electrode. 7. The method according to claim 6, comprising the step of coating the electrode with a metal.