Patent US3851274A successfully refreshed from Google Patents.
US3851274A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recirculating liquid-nitrogen-coolant system for solid-state lasers
Assignee: United States Atomic Energy Commission
•
Filing: 1973-06-29
•
Granted: 1974-11-26
•
Expires: 1993-06-29
Abstract
Abstract A recirculating liquid-nitrogen-coolant system for solid-state lasers permits prolonged continuous operation of the laser at liquid-nitrogen temperatures without boiling the liquid-nitrogen in contact with the laser rod. A liquid-coolant pump, submerged beneath the surface of liquid-nitrogen contained within a Dewar vessel at atmospheric pressure, pumps liquid-nitrogen at an increased pressure through a heat exchanger, similarly submerged within the liquid-nitrogen at atmospheric pressure, to a laser head supporting a solid laser rod. The pressurized liquidnitrogen, which has been cooled below its effective boiling point in passing through the heat exchanger, passes over the surface of the solid laser rod and absorbs heat from the laser rod without the liquid-nitrogen''s temperature being raised above the increased effective boiling temperature, thereby precluding boiling of the liquid-nitrogen. The liquid-nitrogen exits from the laser head and is returned to the Dewar vessel for recirculation. Recirculation of the liquid-nitrogen from the Dewar vessel through the laser head permits continuous cooling of the laser during prolonged and continuous operation.
Inventors
- 👤 S Solin
- 👤 J Doehler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:06
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/02; H01S3/04; H01S3/042; H01S3/0407
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
192 words
A recirculating liquid-coolant system for solid-state lasers comprising: a. a Dewar vessel containing liquid-coolant; b. a liquid-coolant pump, including an intake and an exhaust, submerged beneath said coolant in said Dewar vessel, the intake of said liquid-coolant pump being exposed to the liquid-coolant within said Dewar vessel; c. a first heat exchanger, including an inlet and an outlet, submerged beneath the liquid-coolant in said Dewar vessel, the exhaust of said liquid-coolant pump connected to the inlet of said first heat exchanger; d. a solid laser rod; e. a laser head supporting said solid laser rod therein and including a liquid-coolant inlet and a liquid-coolant outlet disposed to provide coolant access to said laser rod; f. a liquid-coolant feeder conduit interconnecting the outlet of said first heat exchanger and the inlet of said laser head; g. a second heat exchanger, including an inlet and an outlet, submerged beneath the surface of the liquid-coolant within said Dewar vessel, the outlet of said second heat exchanger opening to the interior of said Dewar vessel; and h. a liquid-coolant return conduit interconnecting the outlet of said laser head and the inlet of said second heat exchanger.
Claim 2
Dependent Claim
192 words
A recirculating liquid-coolant system for solid-state lasers comprising: a. a Dewar vessel containing liquid-coolant; b. a liquid-coolant pump, including an intake and an exhaust, submerged beneath said coolant in said Dewar vessel, the intake of said liquid-coolant pump being exposed to the liquid-coolant within said Dewar vessel; c. a first heat exchanger, including an inlet and an outlet, submerged beneath the liquid-coolant in said Dewar vessel, the exhaust of said liquid-coolant pump connected to the inlet of said first heat exchanger; d. a solid laser rod; e. a laser head supporting said solid laser rod therein and including a liquid-coolant inlet and a liquid-coolant outlet disposed to provide coolant access to said laser rod; f. a liquid-coolant feeder conduit interconnecting the outlet of said first heat exchanger and the inlet of said laser head; g. a second heat exchanger, including an inlet and an outlet, submerged beneath the surface of the liquid-coolant within said Dewar vessel, the outlet of said second heat exchanger opening to the interior of said Dewar vessel; and h. a liquid-coolant return conduit interconnecting the outlet of said laser head and the inlet of said second heat exchanger.
Claim 3
Dependent Claim
221 words
The system in accordance with claim 1 wherein said laser head supporting said solid laser rod comprises: a. a central element housing said laser rod, said central element including a sealed inner tube portion composed of a light-transmitting material, and means or supporting said solid laser rod within said central element to extend through the ends of said sealed inner tube portion in sealed relationship therewith; b. a sealed tubular outer element including a portion composed of light-transmitting material; c. spacing members supporting said central element within said outer element in spaced relation thereto such that said central element sealed inner tube portion is concentrically disposed within the light-transmitting portion of said outer element; d. liquid-coolant inlet means and liquid-coolant outlet means passing through said outer element in sealed relation therewith and communicating with the interior of said central element sealed inner tube portion through the opposite ends thereof in sealed relation therewith to permiT liquid coolant access to said laser rod; e. a light-transmitting window sealingly mounted in one end of said sealed outer element, said window aligned with said laser rod to permit propagation of the laser light from said laser head; and f. evacuation means communicating with the interior of said outer element to permit evacuation thereof including the space between said central element and said outer element.
Claim 4
Dependent Claim
103 words
The system according to claim 2 wherein said sealed tubular outer element includes: a middle portion, said middle portion including an outer double-walled tube composed of a light-transmitting material, the walls of said outer double-walled tube being sealed together at their ends; an inlet and an outlet associated with said outer double-walled tube and communicating with the space between the double-walls to provide cooling fluid access therebetween; two end portions sealingly engaging said middle portion at the opposite ends thereof, said liquid-coolant inlet means and said liquid-coolant outlet means sealingly passing through said outer element through the opposite two said end portions respectively.
Claim 5
Dependent Claim
132 words
The system according to claim 3 wherein said means for supporting said laser rod within said central element comprise: end caps engaging said inner tube at each of its two ends, each of said end caps including an aperture therethrough accepting said laser rod in a supportive relationship therewith near the opposite ends thereof; sealing means effecting a sealed supportive relationship between said end caps and said laser rod; and seals bonding said end caps to said inner tube at its ends in vacuum sealed relationship therewith; and wherein said central element further includes radiation shields surrounding each end cap and the seal between the end cap and said inner tube and engaging said end caps, said spacing members engaging said radiation shields to support said central element within said outer element.
Claim 6
Dependent Claim
75 words
The system in accordance with claim 4 wherein said sealing means between said end caps and said laser rod comprise: V-shaped grooves surrounding said apertures in said end caps of said inner tube; indium O-rings disposed in said grooves and engaging said laser rod extending through said apertures; stainless steel bushings engaging said O-rings and pressing said O-rings in said V-shaped grooves to effect a sealable engagement between said laser rod and said end caps.
Claim 7
Dependent Claim
136 words
The system in accordance with claim 4 wherein said liquid-coolant inlet means and liquid-coolant outlet means comprise: a liquid-coolant inlet neck on one said end portion of said outer element and a liquid-coolant outlet neck on the opposite said end portion; a liquid-coolant inlet cap and a liquid-coolant outlet cap in sealed engagement with said liquid-coolant inlet neck and said liquid-coolant outlet neck respectively; a liquid-coolant inlet tube passing through said inlet cap and said inlet neck in sealed relation with said inlet cap and sealingly communicating with the interior of said inner tube through an end cap thereof; and a liquid-coolant outlet tube passing through said outlet cap and said outlet neck in sealed relation with said outlet cap and sealingly communicating with the interior of said inner tube through the opposite end cap thereof.
Claim 8
Dependent Claim
61 words
The system in accordance with claim 6 wherein said seals bonding said end caps to said inner tube are epoxy seals; and wherein said laser head further comprises gold-plated copper braids thermally connecting each of said radiation shields surrounding said seals and said end caps to the liquid-coolant inlet tube and liquid-coolant outlet tube respectively to heat sink the radiation shields.
Claim 9
Dependent Claim
12 words
The system in accordance with claim 7 wherein said liquid-coolant is liquid-nitrogen.
Claim 10
Dependent Claim
29 words
The system according to claim 8 wherein said liquid-coolant pump is a mechanical gear pump for pumping said liquid-nitrogen to said laser head at a pressure above atmospheric pressure.
Claim 11
Dependent Claim
240 words
The system in accordance with claim 9 wherein said pump comprises: a. a pump body defining a pump cavity therein; b. a drive shaft extending through said pump cavity through said pump body in sealed rotational relationship therewith; c. a freely rotating second shaft extending through said pump cavity parallel to said drive shaft; d. a stainless steel cog gear mounted within said cavity on said drive shaft in operative rotational cooperation therewith; e. a fiber cog gear mounted within said cavity on said second shaft in operative rotational cooperation therewith and in meshing engagement with said stainless steel gear; said stainless steel gear and said fiber sized so as to rotate in very close tolerance with the interior surface of said pump body; f. a pump intake disposed on one side of said body opening to said cavity facing said meshing gears in a direction perpendicular to their axes of rotation, said intake sized to expose said stainless steel gear and said fiber gear to the liquid-coolant in which said pump is submerged, and providing liquid-coolant access to said gears; g. a pump exhaust disposed on the opposite side of said body opening to said cavity facing said meshing gears transverse the gears from said intake on a line through the meshing portions of the gears, said exhaust communicating with said intake through that portion of said cavity between said gears and the interior surface of said pump body.
Claim 12
Dependent Claim
79 words
The system in accordance with claim 10 wherein said pump further comprises: a stainless steel shim stock inserted between said fiber gear and said pump body and a fiber gasket inserted between said stainless steel gear and pump body, said shim stock and said gasket serving to compensate for the contraction of said gears and to maintain the close tolerance between said gears and the effective interior surface of said pump body when said pump is at liquid-nitrogen temperature.
Claim 13
Independent Claim
195 words
A method of cooling a solid-state laser rod comprising: a. pumping a liquid-coolant from a reservoir of said coolant at atmospheric pressure to an increased pressure so as to raise the boiling point of said coolant at the increased pressure; b. cooling said coolant at the increased pressure to the temperature of the coolant at atmospheric pressure to lower the temperature of said coolant at the increased pressure below its effective boiling point; c. continuously passing said pressurized and cooled coolant over the surface of the solid laser rod at the increased pressure to cool the laser rod and to absorb any heat generated by the laser rod during operation of the laser and raise the temperature of the coolant at the increased pressure, said continuous passing of coolant over the laser rod being effected at a rate to maintain the temperature of the coolant at the increased pressure below its effective boiling point preventing boiling of the liquid coolant passing over the laser rod; d. returning said heated coolant at the increased pressure to the reservoir of coolant at atmospheric pressure; and e. continuously so recirculating the coolant between the reservoir and the laser.
Claim 14
Independent Claim
195 words
A method of cooling a solid-state laser rod comprising: a. pumping a liquid-coolant from a reservoir of said coolant at atmospheric pressure to an increased pressure so as to raise the boiling point of said coolant at the increased pressure; b. cooling said coolant at the increased pressure to the temperature of the coolant at atmospheric pressure to lower the temperature of said coolant at the increased pressure below its effective boiling point; c. continuously passing said pressurized and cooled coolant over the surface of the solid laser rod at the increased pressure to cool the laser rod and to absorb any heat generated by the laser rod during operation of the laser and raise the temperature of the coolant at the increased pressure, said continuous passing of coolant over the laser rod being effected at a rate to maintain the temperature of the coolant at the increased pressure below its effective boiling point preventing boiling of the liquid coolant passing over the laser rod; d. returning said heated coolant at the increased pressure to the reservoir of coolant at atmospheric pressure; and e. continuously so recirculating the coolant between the reservoir and the laser.
References Cited (Backward Citations)
US3361989A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-25 | 1978-05-27 | 1978-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-25 | 1982-05-27 | 1982-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-25 | 1986-05-27 | 1986-11-26 | $7700.00 | Window Closed / Lapsed |