[go: up one dir, main page]

WO2004023613A1 - Cooling jacket for a flashlamp or arc lamp - Google Patents

Cooling jacket for a flashlamp or arc lamp Download PDF

Info

Publication number
WO2004023613A1
WO2004023613A1 PCT/GB2003/003644 GB0303644W WO2004023613A1 WO 2004023613 A1 WO2004023613 A1 WO 2004023613A1 GB 0303644 W GB0303644 W GB 0303644W WO 2004023613 A1 WO2004023613 A1 WO 2004023613A1
Authority
WO
WIPO (PCT)
Prior art keywords
cooling jacket
flashlamp
lamp
arc lamp
arc
Prior art date
Application number
PCT/GB2003/003644
Other languages
French (fr)
Inventor
Antony David Case
Original Assignee
Qinetiq Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Qinetiq Limited filed Critical Qinetiq Limited
Priority to AU2003255830A priority Critical patent/AU2003255830A1/en
Publication of WO2004023613A1 publication Critical patent/WO2004023613A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/70—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr
    • H01J61/80—Lamps suitable only for intermittent operation, e.g. flash lamp
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/52—Cooling arrangements; Heating arrangements; Means for circulating gas or vapour within the discharge space
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/84—Lamps with discharge constricted by high pressure
    • H01J61/90—Lamps suitable only for intermittent operation, e.g. flash lamp
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/0915—Processes or apparatus for excitation, e.g. pumping using optical pumping by incoherent light
    • H01S3/092—Processes or apparatus for excitation, e.g. pumping using optical pumping by incoherent light of flash lamp

Definitions

  • the invention relates to cooling jackets for flashlamps and arc lamps, to flashlamps and arc lamps per se, and to lasers pumped by flashlamps and arc lamps which have cooling jackets.
  • the invention also relates to methods of fabricating cooling jackets.
  • Flashlamps, arc lamps and similar lamps are used, inter alia, for pumping lasers.
  • Various optical sources have been employed in the past to pump lasers, however today only flashlamps, arc lamps and laser-diodes are of practical interest.
  • laser-diodes have the benefits of robustness, electrical efficiency, longevity and good spectral overlap with ions typically used in solid-state lasers (e.g. ions of rare-earth elements), flashlamps and arc lamps remain useful, particularly in high output power lasers.
  • a flashlamp is an elongate device comprising a linear or helical quartz tube filled with an inert gas (e.g. xenon or krypton at a pressure of 200 - 700 torr at room temperature) and designed such that, in operation, a plasma fills most of the tube.
  • Electrodes are commonly sealed into the body of the flashlamp by one of two techniques. In the first technique, a tungsten electrode is sealed to the quartz tube with highly-doped borsilica glass. A copper rod is used in the second technique; one end of the rod is brazed to an electrode and the other is welded to a copper-plated nickel cup. Indium solder is used to seal the cup to an end of the quartz tube.
  • Arc lamps are of similar construction.
  • cooling of the quartz tube and electrode-seal areas is provided either by a gaseous coolant such as forced air or pressurised nitrogen, or by a liquid coolant such as water, a water-alcohol mixture or a CFC.
  • a gaseous coolant such as forced air or pressurised nitrogen
  • a liquid coolant such as water, a water-alcohol mixture or a CFC.
  • the coolant is circulated in an outer cooling jacket of the flashlamp or arc lamp.
  • the outer cooling jacket is reusable after the lamp itself has reached the end of it useful life.
  • the cooling jacket is inextricably comprised in the lamp.
  • a problem with flashlamps and arc lamps having cooling jackets is that a significant fraction of radiation produced by the lamp undergoes total internal reflection at the outer surface of the cooling jacket and is thus trapped rather than made available for use.
  • trapped radiation is not delivered to the laser's gain medium. Up to 40% of the radiation generated by a flashlamp or arc lamp may be lost by this mechanism. In addition to reducing overall efficiency, such loss results in less effective cooling of the lamp. In the case of flashlamp- and arc lamp-pumped lasers, overall electrical-to-optical conversion efficiency is limited by this effect.
  • An object of the present invention is to mitigate these problems.
  • this object is achieved by a cooling jacket for a flashlamp or arc lamp characterised in that an outer surface of the jacket has a roughness sufficient to substantially reduce total internal reflection of radiation at said surface.
  • the roughened surface reduces total internal reflection so that only 15 to 20% of the radiation generated by a flashlamp or arc lamp within the jacket remains trapped therein, thus increasing the optical output power available for use.
  • a second aspect of the invention provides a method of fabricating a cooling jacket of the invention, the method comprising the step of applying an etching agent to the outer surface of a cooling jacket.
  • etching may be carried out using an etching creme comprising ammonium bifluoride or hydrofluoric acid.
  • sandblasting or manual abrasion may be employed. Sand paper or glass paper may be used to effect manual abrasion.
  • a flashlamp or arc lamp comprising an outer cooling jacket according to the first aspect of the invention is provided by third aspect of the invention. Such a lamp has an improved electrical-to-optical conversion efficiency compared to a flashlamp or arc lamp of the prior art.
  • a fourth aspect of the invention provides a flashlamp- or arc lamp-pumped laser comprising a flashlamp or arc lamp according to the third aspect of the invention. Such a laser has a higher output energy and a higher electrical-to-optical conversion efficiency than prior art flashlamp- or arc lamp-pumped lasers.
  • cooling jackets typically envelop the whole of the quartz tube of a flashlamp or arc lamp
  • the invention may also be applied to a cooling jacket which only partially surrounds a flashlamp or arc lamp.
  • Embodiments of the invention are described below by way of example only.
  • the invention may be put into practice by etching the outer surface of a quartz cooling jacket of a flashlamp with ammonium bifluoride-based etching creme, for example Etchall ® , as follows. Open ends of the jacket are stoppered using fluoride-resistant stoppers (e.g. Subaseal ® stoppers) to prevent etching of the inner surface of the jacket.
  • a plastic measuring cylinder is filled with etching creme and the jacket completely immersed therein for 24 hours (although the exact time is not critical).
  • a cover plate is placed on top of the cylinder to ensure that the jacket remains fully immersed in the etching creme.
  • Etching may also be carried out using hydrofluoric acid (HF) or HF-based products such as HF paste, by sandblasting or by manual abrasion. Sand-paper or glass- paper is useful in the latter case.
  • HF hydrofluoric acid
  • HF-based products such as HF paste
  • Sand-paper or glass- paper is useful in the latter case.
  • the cooling tubes of the flashlamps of a Cocoa-Tinn Mark II flashlamp-pumped dye laser were etched with Etchall ® in order to obtain increased output power from the laser. Measurements of pulse energy were made before and after etching, the arrangement of the laser otherwise being the same in both cases.

Landscapes

  • Lasers (AREA)

Abstract

A cooling jacket for a flashlamp or arc lamp has an outer surface roughened by an etching agent, sandblasting or manual abrasion. This reduces the fraction of radiation generated by a lamp having a cooling jacket and undergoing total internal reflection at the surface, thus increasing the useful optical output power of the lamp. A flashlamp- or arc-lamp pumped laser having a lamp with such a cooling jacket shows improved overall electrical-to-optical conversion efficiency and higher output energy for a given pump energy.

Description

COOLING JACKET FOR A FLASHLAMP OR ARC LAMP
The invention relates to cooling jackets for flashlamps and arc lamps, to flashlamps and arc lamps per se, and to lasers pumped by flashlamps and arc lamps which have cooling jackets. The invention also relates to methods of fabricating cooling jackets.
Flashlamps, arc lamps and similar lamps are used, inter alia, for pumping lasers. Various optical sources have been employed in the past to pump lasers, however today only flashlamps, arc lamps and laser-diodes are of practical interest. Although laser-diodes have the benefits of robustness, electrical efficiency, longevity and good spectral overlap with ions typically used in solid-state lasers (e.g. ions of rare-earth elements), flashlamps and arc lamps remain useful, particularly in high output power lasers.
A flashlamp is an elongate device comprising a linear or helical quartz tube filled with an inert gas (e.g. xenon or krypton at a pressure of 200 - 700 torr at room temperature) and designed such that, in operation, a plasma fills most of the tube. Electrodes are commonly sealed into the body of the flashlamp by one of two techniques. In the first technique, a tungsten electrode is sealed to the quartz tube with highly-doped borsilica glass. A copper rod is used in the second technique; one end of the rod is brazed to an electrode and the other is welded to a copper-plated nickel cup. Indium solder is used to seal the cup to an end of the quartz tube. Arc lamps are of similar construction. In the case of a flashlamp or arc lamp with a high average optical output power, cooling of the quartz tube and electrode-seal areas is provided either by a gaseous coolant such as forced air or pressurised nitrogen, or by a liquid coolant such as water, a water-alcohol mixture or a CFC. The coolant is circulated in an outer cooling jacket of the flashlamp or arc lamp. In many designs, the outer cooling jacket is reusable after the lamp itself has reached the end of it useful life. In other designs the cooling jacket is inextricably comprised in the lamp.
A problem with flashlamps and arc lamps having cooling jackets is that a significant fraction of radiation produced by the lamp undergoes total internal reflection at the outer surface of the cooling jacket and is thus trapped rather than made available for use. For example, in a flashlamp- or arc lamp-pumped laser, trapped radiation is not delivered to the laser's gain medium. Up to 40% of the radiation generated by a flashlamp or arc lamp may be lost by this mechanism. In addition to reducing overall efficiency, such loss results in less effective cooling of the lamp. In the case of flashlamp- and arc lamp-pumped lasers, overall electrical-to-optical conversion efficiency is limited by this effect.
An object of the present invention is to mitigate these problems.
According to a first aspect of the present invention, this object is achieved by a cooling jacket for a flashlamp or arc lamp characterised in that an outer surface of the jacket has a roughness sufficient to substantially reduce total internal reflection of radiation at said surface. The roughened surface reduces total internal reflection so that only 15 to 20% of the radiation generated by a flashlamp or arc lamp within the jacket remains trapped therein, thus increasing the optical output power available for use.
A second aspect of the invention provides a method of fabricating a cooling jacket of the invention, the method comprising the step of applying an etching agent to the outer surface of a cooling jacket. Conveniently, etching may be carried out using an etching creme comprising ammonium bifluoride or hydrofluoric acid. Alternatively, sandblasting or manual abrasion may be employed. Sand paper or glass paper may be used to effect manual abrasion.
A flashlamp or arc lamp comprising an outer cooling jacket according to the first aspect of the invention is provided by third aspect of the invention. Such a lamp has an improved electrical-to-optical conversion efficiency compared to a flashlamp or arc lamp of the prior art. A fourth aspect of the invention provides a flashlamp- or arc lamp-pumped laser comprising a flashlamp or arc lamp according to the third aspect of the invention. Such a laser has a higher output energy and a higher electrical-to-optical conversion efficiency than prior art flashlamp- or arc lamp-pumped lasers.
Although cooling jackets typically envelop the whole of the quartz tube of a flashlamp or arc lamp, the invention may also be applied to a cooling jacket which only partially surrounds a flashlamp or arc lamp.
Embodiments of the invention are described below by way of example only. The invention may be put into practice by etching the outer surface of a quartz cooling jacket of a flashlamp with ammonium bifluoride-based etching creme, for example Etchall®, as follows. Open ends of the jacket are stoppered using fluoride-resistant stoppers (e.g. Subaseal® stoppers) to prevent etching of the inner surface of the jacket. A plastic measuring cylinder is filled with etching creme and the jacket completely immersed therein for 24 hours (although the exact time is not critical). A cover plate is placed on top of the cylinder to ensure that the jacket remains fully immersed in the etching creme.
Etching may also be carried out using hydrofluoric acid (HF) or HF-based products such as HF paste, by sandblasting or by manual abrasion. Sand-paper or glass- paper is useful in the latter case.
The cooling tubes of the flashlamps of a Cocoa-Tinn Mark II flashlamp-pumped dye laser were etched with Etchall® in order to obtain increased output power from the laser. Measurements of pulse energy were made before and after etching, the arrangement of the laser otherwise being the same in both cases.
The mean pulse energy of optical pulses output from the laser before etching was
2.21 J. After etching, the mean pulse energy was 2.90 J, corresponding to an increase in mean pulse energy due to etching of 31%. A one-sided two-sample t- test resulted in a specific probability value less than 0.001, giving overwhelming evidence that that energy of the pulses was increased.

Claims

1. A cooling jacket for a flashlamp or arc lamp characterised in that an outer surface of the jacket has a roughness sufficient to substantially reduce total internal reflection of radiation at said surface.
2. A flashlamp or arc lamp comprising a cooling jacket according to claim 1.
3. A laser comprising a flashlamp or an arc lamp according to claim 2.
4. A method of fabricating the cooling jacket of claim 1, the method comprising the step of applying an etching agent to the outer surface of a cooling jacket.
5. The method of claim 4 wherein the etching agent comprises ammonium bifluoride.
6. The method of claim 4 wherein the etching agent comprises hydrofluoric acid.
7. A method of fabricating the cooling jacket of claim 1 comprising the step of roughening the outer surface of a cooling jacket by sandblasting.
8. A method of fabricating the cooling jacket of claim 1 comprising the step of roughening the outer surface of a cooling jacket by manual abrasion.
9. The method of claim 9 wherein the manual abrasion is carried out using glass paper.
10. The method of claim 9 wherein the. manual abrasion is carried out using sand paper.
PCT/GB2003/003644 2002-09-03 2003-08-20 Cooling jacket for a flashlamp or arc lamp WO2004023613A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003255830A AU2003255830A1 (en) 2002-09-03 2003-08-20 Cooling jacket for a flashlamp or arc lamp

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0220424A GB2392719A (en) 2002-09-03 2002-09-03 Cooling jacket for a flashlamp
GB0220424.6 2002-09-03

Publications (1)

Publication Number Publication Date
WO2004023613A1 true WO2004023613A1 (en) 2004-03-18

Family

ID=9943399

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2003/003644 WO2004023613A1 (en) 2002-09-03 2003-08-20 Cooling jacket for a flashlamp or arc lamp

Country Status (3)

Country Link
AU (1) AU2003255830A1 (en)
GB (1) GB2392719A (en)
WO (1) WO2004023613A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1334009A (en) * 1971-05-19 1973-10-17 Gen Electric Co Ltd Laser devices
US3803509A (en) * 1971-04-30 1974-04-09 Inst Angewandite Physik Der Un Apparatus for optical excitation of a laser rod
US4207541A (en) * 1978-02-21 1980-06-10 General Electric Company Cooling jacket for laser flash lamps
GB2193371A (en) * 1986-07-28 1988-02-03 Gen Electric Laser pumped by electromagnetic radiation

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3569754A (en) * 1968-06-19 1971-03-09 Dyonics Inc Flash source
EP0105230A3 (en) * 1982-09-30 1986-01-15 General Electric Company Triggering and cooling apparatus for laser flashlamps

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3803509A (en) * 1971-04-30 1974-04-09 Inst Angewandite Physik Der Un Apparatus for optical excitation of a laser rod
GB1334009A (en) * 1971-05-19 1973-10-17 Gen Electric Co Ltd Laser devices
US4207541A (en) * 1978-02-21 1980-06-10 General Electric Company Cooling jacket for laser flash lamps
GB2193371A (en) * 1986-07-28 1988-02-03 Gen Electric Laser pumped by electromagnetic radiation

Also Published As

Publication number Publication date
GB0220424D0 (en) 2002-10-09
GB2392719A (en) 2004-03-10
AU2003255830A1 (en) 2004-03-29

Similar Documents

Publication Publication Date Title
US7800308B2 (en) Excimer lamp
JP4569636B2 (en) Excimer discharge lamp
US6249086B1 (en) High-pressure discharge lamp including a limited amount of carbon remaining on an electrode surface
KR100973121B1 (en) Excimer lamp
JP2775694B2 (en) Discharge lamp
KR100799300B1 (en) High Intensity Discharge Lamp and Its Starting Method
EP2360714A2 (en) High pressure discharge lamp and method for sealing a bulb thereof
JP3204189B2 (en) Short arc type ultra-high pressure discharge lamp
WO2004023613A1 (en) Cooling jacket for a flashlamp or arc lamp
JP5169914B2 (en) Excimer lamp device
JP4752944B2 (en) Excimer discharge lamp
US20110095684A1 (en) Excimer lamp
Brown et al. A 6.5-J flashlamp-pumped Ti: Al/sub 2/O/sub 3/laser
Erickson Flashlamp-pumped titanium: sapphire laser
JP2004227820A (en) Discharge lamp
US7099365B2 (en) Oscillation method and device of fluorine molecular laser
HU202013B (en) Impulsed inert gas discharge lamp
JP5316079B2 (en) Excimer discharge lamp
Boquillon et al. Flashlamp-pumped Ti: Sapphire laser: Influence of the rod figure of merit and Ti3+ concentration
CN1553466A (en) High-power composite function quartz glass tube pulse xenon lamp
JP2003086872A (en) Low-pressure axial excitation type F2 laser device
CN2463991Y (en) Pulse pre-ionization longitudinal discharge laser
EP0081918A2 (en) High pressure sodium lamps
Boquillon et al. Flashlamp-pumped Ti: sapphire laser with different rods grown by Czochralski and Verneuil methods
Sabaeian et al. Design and construction of a home-made and cheaper argon arc lamp

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP