GB2244851A - Conical mirror laser resonator - Google Patents

Conical mirror laser resonator Download PDF

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Publication number
GB2244851A
GB2244851A GB8828115A GB8828115A GB2244851A GB 2244851 A GB2244851 A GB 2244851A GB 8828115 A GB8828115 A GB 8828115A GB 8828115 A GB8828115 A GB 8828115A GB 2244851 A GB2244851 A GB 2244851A
Authority
GB
United Kingdom
Prior art keywords
conical
resonator
laser resonator
conical mirror
mirror
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
GB8828115A
Other versions
GB8828115D0 (en
Inventor
Vijitha Maithri Weerasinghe
Roger David Hibberd
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial College of Science Technology and Medicine
IMPERIAL COLLEGE
Original Assignee
Imperial College of Science Technology and Medicine
IMPERIAL COLLEGE
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 Imperial College of Science Technology and Medicine, IMPERIAL COLLEGE filed Critical Imperial College of Science Technology and Medicine
Priority to GB8828115A priority Critical patent/GB2244851A/en
Publication of GB8828115D0 publication Critical patent/GB8828115D0/en
Publication of GB2244851A publication Critical patent/GB2244851A/en
Application status is Withdrawn legal-status Critical

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES 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
    • H01S3/00Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08Construction or shape of optical resonators or components thereof
    • H01S3/08059Constructional details of the reflector, e.g. shape
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES 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
    • H01S3/00Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/23Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
    • H01S3/2308Amplifier arrangements, e.g. MOPA
    • H01S3/2316Cascaded amplifiers

Abstract

A laser resonator has a conical mirror with a nominal inclusive angle of 90 degrees. Two conical mirrors may be used, one as the end reflector and the other as the output coupler. The conical resonator may be used in an oscillator/amplifier system (Fig 2). A circularly polarised beam is produced as required for multi-directional processing (eg cutting/drilling). <IMAGE>

Description

CONICAL MIRROR RESONATOR DESCRIPTION The invention is concerned with a laser resonator configuration having a conical mirror end reflector. The nominal inclusive angle of the mirror cone is ninety degrees as shown in Figure 1. The resonator will be referred to as the conical resonator.

The purpose of the invention is to improve certain qualities of the laser beam in order to obtain an advantageous effect related to processing of materials.

It is known that the state of polarisation of the laser beam is of relevance to cutting, scribing and drilling. A laser beam produced from a folded cavity will be plane polarised because of the enhanced 'S' reflectance. As a result optimum processing can only be carried out in a certain direction. Consistent multi-directional processing requires a circularly polarised beam which is achieved using an additional optical element. A plane polarised beam when used for drilling produces a distorted hole shape rather than the circular hole that is required. The state of polarisation of a laser beam produced by a straight-spherical or plane-parallel resonator will be random. As a result consistent results are not obtained in processing materials.

The laser beam produced by the conical resonator has produced results in cutting and drilling to indicate that at a given time, the beam is equally polarised in all directions.

Compared to straight and folded resonators with plane or hemispherical mirrors, cutting at faster speeds in a non-directional manner is possible using the beam from the conical resonator. Further, holes drilled using the conical resonator beam are circular compared to distorted shapes produced by the plane polarised beams.

A further aspect is that the conical resonator is less sensitive to mirror misalignment compared to non-confocal straight and folded resonators with plane or hemispherical mirrors. From geometrical optics, it can be shown that the deviation of a ray after two reflections from two mirrors inclined to each other at an angle 'a' is independent of the angle of incidence and is given by 2 (it - a ) if the plane of incidence is perpendicular to the line of inter-section of the two mirrors. This is also valid for the conical mirror; therefore, the conical resonator will be less sensitive to mirror misalignment because the mode axis is not displaced.

A another observed aspect is the 'doughnut' structure and the good symmetry of the intensity distribution of the beam from the conical resonator. The 'doughnut' structure is particularly useful in surface modification processes because the less centralised intensity of the beam. Ray reversal has the result that mode quality of the conical resonator is less susceptible to degradation by optical and gain inhomogeneities of the medium.

The power produced by the conical resonator is comparable to the power produced by a straight resonator with a hemispherical mirror, under the same conditions.

A further embodiment of the conical mirror resonator is shown in Figure 2.

Claims (5)

  1. Claims
    Conical Mirror Resonator 1. A laser resonator configuration having conical mirrors with a nominal inclusive angle of 90 degrees as its reflectors.
  2. 2. A laser resonator, according to claim 1, in which the conical mirror is the end reflector.
  3. 3. A laser resonator, according to claim 1, in which the conical mirror is the partially reflecting output coupler.
  4. 4. A laser resonator, according to claim 1, in which the conical mirrors are the output coupler and the end reflector.
  5. 5. A laser resonator, according to any one of claims 1 to 4, which is an oscillator in an oscillator/amplifier system.
GB8828115A 1988-12-02 1988-12-02 Conical mirror laser resonator Withdrawn GB2244851A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8828115A GB2244851A (en) 1988-12-02 1988-12-02 Conical mirror laser resonator

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8828115A GB2244851A (en) 1988-12-02 1988-12-02 Conical mirror laser resonator

Publications (2)

Publication Number Publication Date
GB8828115D0 GB8828115D0 (en) 1989-01-05
GB2244851A true GB2244851A (en) 1991-12-11

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB8828115A Withdrawn GB2244851A (en) 1988-12-02 1988-12-02 Conical mirror laser resonator

Country Status (1)

Country Link
GB (1) GB2244851A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0911922A1 (en) * 1997-10-24 1999-04-28 TRUMPF LASERTECHNIK GmbH Laser resonator
EP1233483A1 (en) * 2001-02-19 2002-08-21 VDM Laser Optics Method and device for generating an optical invariant field
US7786406B2 (en) * 2002-11-22 2010-08-31 Boston Scientific Scimed, Inc. Laser stent cutting

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB985204A (en) * 1960-10-07 1965-03-03 Western Electric Co Improvements in or relating to optical or infrared maser cavities
US3283262A (en) * 1963-05-01 1966-11-01 Bell Telephone Labor Inc Optical maser operating in the tmon mode
US3628178A (en) * 1968-08-14 1971-12-14 United Aircraft Corp Diffractive coupling laser mirror
US3660779A (en) * 1970-01-02 1972-05-02 American Optical Corp Athermalization of laser rods
US4514850A (en) * 1983-05-16 1985-04-30 Rockwell International Corporation Common-pass decentered annular ring resonator
US4516244A (en) * 1983-09-01 1985-05-07 Rockwell International Corporation Common-pass decentered annular ring resonator with improved polarization control
US4731794A (en) * 1985-06-03 1988-03-15 Max-Planck-Gesellschaft Zur Forderung Der Wissenschaften E.V. Optical laser pumping system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB985204A (en) * 1960-10-07 1965-03-03 Western Electric Co Improvements in or relating to optical or infrared maser cavities
US3283262A (en) * 1963-05-01 1966-11-01 Bell Telephone Labor Inc Optical maser operating in the tmon mode
US3628178A (en) * 1968-08-14 1971-12-14 United Aircraft Corp Diffractive coupling laser mirror
US3660779A (en) * 1970-01-02 1972-05-02 American Optical Corp Athermalization of laser rods
US4514850A (en) * 1983-05-16 1985-04-30 Rockwell International Corporation Common-pass decentered annular ring resonator
US4516244A (en) * 1983-09-01 1985-05-07 Rockwell International Corporation Common-pass decentered annular ring resonator with improved polarization control
US4731794A (en) * 1985-06-03 1988-03-15 Max-Planck-Gesellschaft Zur Forderung Der Wissenschaften E.V. Optical laser pumping system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0911922A1 (en) * 1997-10-24 1999-04-28 TRUMPF LASERTECHNIK GmbH Laser resonator
EP1233483A1 (en) * 2001-02-19 2002-08-21 VDM Laser Optics Method and device for generating an optical invariant field
US7786406B2 (en) * 2002-11-22 2010-08-31 Boston Scientific Scimed, Inc. Laser stent cutting

Also Published As

Publication number Publication date
GB8828115D0 (en) 1989-01-05

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Legal Events

Date Code Title Description
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)