Temperature control of a solid state face pumped laser slab by an active siderail

• US 4,852,109 A
• Filed: 12/02/1988
• Issued: 07/25/1989
• Est. Priority Date: 12/02/1988
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Kuchar, Norman R.
• Primary Examiner(s): Davie, James W.
• Application Number:
  US07/278,997
• Time in Patent Office: 235 Days
• Field of Search: 372/34, 372/35, 372/66
• US Class Current: 372/34
• CPC Class Codes: H01S 3/0405 Conductive cooling, e.g. by heat sinks or thermo-electric elements
• CPC Class Codes: H01S 3/0407 Liquid cooling, e.g. by water
• CPC Class Codes: H01S 3/042 for solid state lasers H01S3/0401 takes precedence
• CPC Class Codes: H01S 3/0606 with polygonal cross-section, e.g. slab, prism H01S3/0604 takes precedence
• CPC Class Codes: H01S 3/08072 Thermal lensing or thermally induced birefringence; Compensation thereof
• CPC Class Codes: H01S 3/08095 Zig-zag travelling beam through the active medium
• CPC Class Codes: H01S 3/131 by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
• CPC Class Codes: H01S 3/1317 by controlling the temperature

Abstract

Optical and thermal distortion in a solid state slab geometry laser are controlled by active siderails disposed at the lateral surfaces of the slab. Each siderail may have a fluid passage therethrough and be connected in a separate fluid circuit which enables the volumetric flow rate and temperature of the fluid through the passageway to be controlled in order to control the temperature of the siderail and, accordingly, the temperature of the slab in regions proximate to the siderail. The invention enables compensation of asymmetric transverse gradients to afford a uniform transverse temperature distribution.

Claims

1. A method of reducing distortion in a solid state laser of the type which comprises a slab of lasing material having a pair of major optical faces disposed parallel to one another and to a longitudinal axis of the slab, at least one face having electromagnetic energy impinging thereon to excite atoms in the lasing material to an elevated energy state, and first and second lateral surfaces disposed perpendicularly to the faces at the sides thereof, each lateral surface having a siderail thereon, the method comprising controlling the temperature of each siderail in order to control a flux of thermal energy across each of the lateral surfaces and a slab temperature proximate each lateral surface.

2. The method of claim 1, wherein said controlling comprises independently controlling the temperature of each siderail to produce a uniform temperature distribution across the slab.

3. The method of claim 1, wherein each siderail has a passageway, and said controlling comprises passing a fluid through the passageway to vary the temperature of the siderail.

4. The method of claim 3, wherein said controlling comprises controlling a volumetric flow rate and an inlet temperature of the fluid in order to control the heat transfer between the fluid and the siderail.

5. The method of claim 1, wherein each siderail has an electrical heater, and wherein said controlling comprises controlling the supply of electrical current to the electrical heater.

6. A laser device comprising a slab of lasing material having a pair of opposed major optical faces disposed parallel to one another and to a longitudinal axis of the slab, and having first and second opposed lateral surfaces disposed perpendicular to the faces at the sides thereof;

means for impinging electromagnetic energy onto at least one of the faces to excite atoms in the slab to an elevated energy state;

first and second heat transferring means disposed at the first and second lateral surfaces, respectively, for independently controlling the temperature at each lateral surface to provide a uniform temperature distribution across the slab in a direction transverse to the longitudinal axis.

7. The laser device of claim 6, wherein said heat transferring means comprises first and second siderails bonded to the first and second lateral surfaces, respectively, and means for controlling the temperature of each siderail.

8. The laser device of claim 7, wherein the temperature controlling means comprises means for controlling a volumetric flow rate of a fluid passing through a passageway in each siderail, and means for controlling a temperature of the fluid entering the passageway, to control a flux of thermal energy across each lateral surface.

9. The laser device of claim 7, wherein each siderail has an electrical heater element within the siderail, and means for controlling electrical current to the heater element.

10. The laser device of claim 6, wherein said laser device comprises a total internal reflection face pumped laser, and said slab has a generally rectangular configuration.

11. A laser device comprising a slab of lasing material having a pair of opposed major optical faces disposed parallel to one another and to a longitudinal axis of the slab, and having first and second opposed lateral surfaces disposed perpendicularly to the faces at the sides thereof;

a siderail disposed on each lateral surface;

means for impinging electromagnetic radiation onto at least one of the faces of the slab to excite atoms in the slab to an elevated energy state; and

means for controlling the temperature of each siderail in order to control the flux of thermal energy across a corresponding lateral surface upon which the siderail is disposed and the slab temperature proximate such lateral surface.

12. The laser device of claim 11, wherein said controlling means comprises means for independently controlling the temperature of each siderail to compensate for an asymmetrical temperature variation transverse to the longitudinal axis.

13. The laser device of claim 11, wherein each siderail has a passageway therethrough, and the temperature controlling means comprises means for passing a fluid through the passageway, and means for controlling a volumetric flow rate and a temperature of the fluid in order to control heat transfer between the fluid and the siderail.

14. The laser device of claim 13, wherein each siderail comprises a pair of members, each having a groove therein, which are joined together to form the passageway therethrough.

15. The laser device of claim 11, wherein each siderail has an electrical heater element, and the temperature controlling means comprises means for controlling an electrical current supplied to the heater element.

16. The laser device of claim 11, wherein the siderails have a dimensional parallel to the lateral surfaces which matches the dimension of the lateral surfaces, and have a length parallel to the longitudinal axis which is greater than a length over which said electromagnetic energy is supplied to said face.

17. The laser device of claim 11, wherein the siderails are formed of another material which blocks optical energy from impinging on the lateral surfaces.

18. The laser device of claim 17, wherein said other material comprises an opaque ceramic.

19. The laser device of claim 17, wherein said other material is reflective.