# US 5,353,293 A · Hybrid cooled ion laser

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- Number: US 5,353,293 A
- Document ID: US5353293A
- Status: Granted
- Kind: A
- Application number: 08/054,313
- Filed: 1993-04-27
- Granted: 1994-10-04
- Earliest claimed: 1993-04-27
- Assignees: Spectra-Physics Lasers, Inc.
- Inventors: William A. Shull
- Web page: https://patentgrep.com/patent/US5353293A

## CPC

- H01S 3/041: for gas lasers {(H01S3/0401 takes precedence)}
- H01S 3/032: for confinement of the discharge, e.g. by special features of the discharge constricting tube
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL

## Abstract

A high output, compact laser having a multi-line spectral output and an internal mirror, integral resonator design is disclosed. The laser structure comprises a laser tube containing a resonant cavity, an output coupler and an active medium. A power supply and coolant assembly are coupled to the laser tube. The coolant assembly is a hybrid coolant scheme wherein one portion of the tube is cooled by circulating water coolant, while another portion or portions are cooled by circulating air. In one aspect, the laser tube includes a ceramic bore surrounded by a sheath sealed at a first end and a second end of the ceramic bore, and coolant is provided between the sheath and the bore. In a further aspect, forced air is directed over a reservoir portion of the tube. The reservoir portion may be manufactured from a metallic alloy comprised of nickel iron cobalt with copper cooling fins brazed to the reservoir to increase thermal cooling efficiency and isothermal distribution of heat.

## Claims

### Claim 1

A high powered laser, comprising:
a laser tube containing a resonator mirror and an output coupler defining a resonator cavity, said tube containing an active medium and said laser tube having a first end defining a first section of said laser tube, and a second end defining a second section of said laser tube;
a first cooling device coupled to a first section of the laser tube made of a ceramic material that has a greater efficiency for removing heat in a high temperature environment than a non-ceramic material, the first section of said laser tube operating at a high temperature, the first cooling device including a circulating liquid coolant to cool said first section;
a second cooling device for cooling, provided to a second section of the laser tube made of non-ceramic material, said second section operating at a lower temperature than the high temperature of the first section of said laser tube, the second cooling device operating substantially by circulating air; and
a power supply coupled to the laser tube.

### Claim 2 (depends on 1)

The laser of claim 1 wherein the laser further includes an anode and a cathode positioned in the laser tube, the anode being positioned in the first section and the cathode being positioned in the second section of the laser tube.

### Claim 3 (depends on 2)

The laser of claim 2 wherein the first section of the laser tube comprises a laser bore portion and the second section of the tube comprises a gas reservoir.

### Claim 4 (depends on 3)

The laser of claim 3 wherein a portion of the anode is in thermal contact with the bore and the circulating liquid coolant, and a portion of the anode is in contact with the circulating air.

### Claim 5 (depends on 3)

The laser of claim 3 wherein a first optical element mounted on an optical seat in the interior of the bore; and
a second optical element mounted on an optical seat in the interior of the gas reservoir.

### Claim 6 (depends on 3)

The laser of claim 3 wherein the bore portion is comprised of a ceramic bore surrounded by a liquid coolant sheath.

### Claim 7 (depends on 6)

The laser of claim 6 wherein the reservoir is comprised of a metallic alloy.

### Claim 8 (depends on 3)

The laser of claim 3 wherein the bore is manufactured from beryllia and the gas reservoir is manufactured from a nickel-iron-cobalt alloy.

### Claim 9 (depends on 3)

The laser of claim 3 wherein the bore section includes a first end and a second end wherein the first end includes an anode mounted therein and the second end is attached to the gas reservoir.

### Claim 10 (depends on 9)

The laser of claim 9 wherein the anode is secured in a cavity in the first end of the ceramic bore.

### Claim 11 (depends on 9)

The laser of claim 9 wherein the anode is manufactured from copper and includes copper cooling fins brazed thereto such that the cooling fins engage the ceramic bore when the anode and fins are placed in a cavity in the bore.

### Claim 12 (depends on 9)

The laser of claim 9 wherein the first cooling device for cooling comprises a cylindrical fluid cooling sheath, sealed at a first end and a second end of the bore portion.

### Claim 13 (depends on 3)

The laser of claim 3 wherein the second cooling device for cooling comprises a plurality of copper cooling fins brazed to the exterior surface of the gas reservoir, and a source of forced air incident on the cooling fins.

### Claim 14

A hybridly cooled high power gas laser, comprising:
a laser tube including an anode, a cathode, a bore that operates at a high temperature, a gas reservoir that operates at a lower temperature than the high temperature of the bore, and optical elements positioned in first and second ends of the tube to define a resonator cavity that produces an output of laser energy, said tube containing an active medium;
a liquid coolant system coupled to the bore; and
an air cooling system directing forced air over the gas reservoir.

### Claim 15 (depends on 14)

The laser of claim 14 wherein the anode is provided in a cavity at one end of the bore.

### Claim 16 (depends on 15)

The laser of claim 15 wherein the liquid coolant system comprises a sheath surrounding the bore and sealed at a first and second ends of the bore, the sheath including fittings allowing circulating coolant to enter a region between the bore and the sheath.

### Claim 17 (depends on 16)

The laser of claim 16 wherein the air cooling system includes a source of forced air directing the air over the reservoir portion at the second end of the bore and over a portion of the anode at the first end of the bore.

### Claim 18

A high energy laser, comprising:
a laser tube, the laser tube comprising:
a gas reservoir having an exterior surface and being comprised of a metallic alloy,
a laser bore that operates at a high temperature, comprised of ceramic and coupled to the gas reservoir which operates at a lower temperature than the high temperature of the bore,
an anode assembly coupled to a first end of the bore,
a cathode mounted in a second end of the tube, and,
first and second optical elements mounted in the first and second ends of the tube defining a resonator that produces a laser output;
a power supply coupled to the anode and cathode;
a coolant flow tube surrounding the laser bore, sealed at a first end and a second ends of the tube, and coupled to e source of recirculating coolant;
metallic cooling fins coupled to the exterior surface of the gas reservoir; and
a source of forced air directed over the cooling fins and a portion of the anode assembly.

### Claim 19 (depends on 18)

The laser of claim 18 wherein the anode assembly includes
a copper anode mounted in a cavity in the first end of the bore;
a housing mounted to the first end of the bore; and
a connector between the housing and the copper anode.

### Claim 20 (depends on 19)

The laser of claim 19 wherein the anode assembly further includes an optical mount assembly coupled to the housing, the first optical element being coupled to the optical mount assembly.

### Claim 21 (depends on 20)

The laser of claim 20 wherein the optical mount assembly includes
a mirror seat, the first optical element being coupled to the mirror seat; and
an end cap for coupling the mirror seat to the housing.

### Claim 22 (depends on 18)

The laser of claim 18 wherein the gas reservoir is positioned at the second end of the tube, the cathode is mounted in the gas reservoir, and an optical mount assembly is mounted in the gas reservoir with the second optical element mounted thereto.

### Claim 23

A high energy laser, comprising:
a tube, having a bore that operates at a high temperature, and a gas reservoir that operates at a lower temperature than the high temperature of the bore;
an anode mounted in one end of the bore;
a cathode mounted in the gas reservoir;
a recirculating water cooling system coupled to the bore;
a device for supplying circulating air over the reservoir region;
a first optical element mounted on an optical seat in the interior of the bore; and
a second optical element mounted on an optical seat in the interior of the gas reservoir.

### Claim 24 (depends on 23)

The laser of claim 23 wherein a gas is provided in the laser tube, the gas comprising a mixture of argon and krypton.

### Claim 25 (depends on 24)

The laser of claim 24 wherein a power supply is coupled to the anode and the cathode, and recirculating coolant in the cooling system does not engage a junction between the bore and the gas reservoir.

### Claim 26 (depends on 25)

The laser of claim 25 wherein the laser provides a multiple spectral line, white light output when the power supply is energized.

### Claim 27 (depends on 25)

The laser of claim 25 a first optical element is mounted on an optical seat in a stainless steel or Kovar anode housing at said one end of the bore; and
a second optical element mounted on an optical seat in the interior of the gas reservoir.

### Claim 28 (depends on 23)

The laser of claim 23 wherein a portion of the anode is in thermal contact with the bore and the recirculating water, and a portion of the anode is in contact with the recirculating air.