USRE35240E - Optical modulators - Google Patents
Optical modulators Download PDFInfo
- Publication number
- USRE35240E USRE35240E US08/070,251 US7025193A USRE35240E US RE35240 E USRE35240 E US RE35240E US 7025193 A US7025193 A US 7025193A US RE35240 E USRE35240 E US RE35240E
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- US
- United States
- Prior art keywords
- crystal
- optical
- modulator
- charge
- path
- 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.)
- Expired - Lifetime
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Classifications
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- 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
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1123—Q-switching
- H01S3/115—Q-switching using intracavity electro-optic devices
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
- G02F1/0305—Constructional arrangements
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2203/00—Function characteristic
- G02F2203/21—Thermal instability, i.e. DC drift, of an optical modulator; Arrangements or methods for the reduction thereof
Definitions
- Optical modulators are known which comprise crystals of a suitable material whose optical properties may be varied by the application of an electric field across the crystal perpendicular to the optical axis of the crystal. The application of such a field affects the polarisation of optical .[.iation.]. .Iadd.radiation .Iaddend.passing through the crystal.
- One of the most common applications of such an optical modulator is in the so-called Q-switch laser, in which the modulator crystal is used to vary the optical conditions within the laser cavity so that .[.laseraction.]. .Iadd.laser action .Iaddend.may be either prevented or induced as required.
- Optimum laser performance requires the Q-switch to change phase modulation of the optical radiation between two distinct and clearly-defined polarisation states. Anything which causes these two states to be less clearly defined will adversely affect the performance of the laser.
- a commonly-used material for a laser Q-switch is a crystal of Lithium Niobate. This material exhibits the pyroelectric effect, as a result of which changes in the temperature of the crystal result in the development of static electric charges of opposite polarity at the opposite ends of the crystal. If this charge is allowed to collect on the faces of the crystal then the performance of the laser will be affected. In normal atmospheres some leakage of the charge will occur. However, Q-switched lasers of the type described above are often sealed into an enclosure with an extremely dry atmosphere, and this prevents charge leaking.
- FIG. 3 shows such an arrangement.
- the main problem with this technique is that the conducting layer 60 interferes with the passage of optical radiation through the end faces of the crystal. Equally, it may be damaged by the power of the optical radiation passing through it. .Iaddend.
- optical modulator which includes a crystal of a material exhibiting the pyroelectric effect and means for dissipating any electric charge built up on the optical faces of the crystal,
- FIG. 1 is a schematic diagram of a common form of Q-switched laser, incorporating an optical modulator
- FIG. 2 is a perspective view of an optical modulator crystal; .[.and.].
- FIG. 3 diagrammatically illustrates a prior art method, as above described, of dissipating accumulated charge on the faces; and .Iaddend.
- FIGS. .[.3.]. .Iadd.4 .Iaddend.to 7 are schematic diagrams illustrating different embodiments of the invention.
- .[.as.]. .Iadd.a .Iaddend.common form of Q-switched laser includes a rod 10 of laser active material, such as Neodymium-YAG together with an associated flash tube 11 for optically pumping the active material.
- Two porro prisms 12 and 13 define the optical cavity of the laser which also includes a polariser 14 and a Q-switch 15.
- the Q-switch is a crystal of a material such as Lithium Niobate and is provided with two electrodes 16 connected to a modulating power supply 17.
- the optical components are arranged along an optical axis 18, with the electrodes 16 on the crystal 15 arranged on opposite sides of the optical axis.
- the Q-switch 15 comprises a crystal of material formed into a block and fastened in an electrically insulating housing 20 as shown in FIG. 2.
- the end faces 21 are those through which the laser radiation passes. It is on these faces in particular that a static electric charge may build up due to the pyroelectric effect. Removal of this static electric charge may be achieved basically in two ways. One involves neutralising the charge in some way, whilst the other involves conducting the charge away from the faces of the crystal. The polarity of the charge depends upon whether the temperature of the crystal is increasing or decreasing.
- FIG. .[.3.]. .Iadd.4 .Iaddend. illustrates one technique which may be used to neutralise any static charge on the end faces of the crystal.
- a source of ions is provided adjacent to each face by emission from point electrodes 30 adjacent to each face but away from the path of any optical radiation.
- a high-voltage power supply 31 is connected to the electrodes. When the supply 31 is energised a stream of ions is emitted by each electrode 30 and these ions of opposite charge to that on the adjacent face of the crystal will be attracted to that face to neutralise the charge caused by the pyroelectric effect. Since the polarity of the charge on a face may vary the power supply 31 should preferably be a high voltage alternating current supply.
- the neutralising ions may be produced by a spark discharge.
- This may use the arrangement shown in FIG. .[.4.]. .Iadd.5 .Iaddend.in which a pair of electrodes 40 is provided, forming a spark gap adjacent to each face, again well clear of the path of optical radiation.
- One electrode of each pair will be, conveniently, connected to ground.
- the high voltage power supply 31, which may be a direct-current supply, may be triggered to produce a spark between each pair of electrodes. This produces a cloud of both positive and negative ions, the appropriate ones of which will neutralise the charge on the face of the crystal.
- FIG. .[.5..]. .Iadd.6. .Iaddend. This involves placing near to each end face of the Q-switching crystal a small radioactive source 50. Each of these sources will emit ionising radiation towards the adjacent face of the crystal. Such radiation will be arrested both by the atmosphere in front of the end faces and by the faces themselves, with the generation of ion pairs, some of which will neutralise the static charge. This process is continuous as it is not practically possible to control the emission of alpha particles from the source.
- FIG. 7 illustrates an arrangement using an electrically conducting blade 70 connected to ground and wiped over the face 21 of the crystal by a motor 71. Other mechanical arrangements could be used.
- the optical components of a Q-switched laser are sometimes enclosed in a sealed container so that the atmosphere may be controlled, particularly to prevent misting of optical surfaces during conditions where condensation might occur.
- Any of the charge-removal techniques described above may be used inside such a sealed container.
- the techniques may also be used on Q-switching crystals of other materials than Lithium Niobate which exhibit the pyroelectric effect.
- the optical modulator may be used in other applications than Q-switched lasers, and all the techniques described above are applicable to such applications.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Nonlinear Science (AREA)
- Optics & Photonics (AREA)
- Electromagnetism (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
- Lasers (AREA)
Abstract
An optical modulator comprises a crystal (15) of material exhibiting the pyroelectric effect, and charge-dissipating means for dissipating any charge built up on the optical faces of the prism. The charge-dissipating means may comprise point electrodes (30) positioned adjacent to the optical faces (21) of the crystal and connected to an alternating-current high-voltage power supply (31). The electrodes produce charged ions which neutralize any charge on the optical faces of the crystal. The crystal may be used as the Q-switch in a laser.
Description
Optical modulators are known which comprise crystals of a suitable material whose optical properties may be varied by the application of an electric field across the crystal perpendicular to the optical axis of the crystal. The application of such a field affects the polarisation of optical .[.iation.]. .Iadd.radiation .Iaddend.passing through the crystal. One of the most common applications of such an optical modulator is in the so-called Q-switch laser, in which the modulator crystal is used to vary the optical conditions within the laser cavity so that .[.laseraction.]. .Iadd.laser action .Iaddend.may be either prevented or induced as required. Optimum laser performance requires the Q-switch to change phase modulation of the optical radiation between two distinct and clearly-defined polarisation states. Anything which causes these two states to be less clearly defined will adversely affect the performance of the laser.
A commonly-used material for a laser Q-switch is a crystal of Lithium Niobate. This material exhibits the pyroelectric effect, as a result of which changes in the temperature of the crystal result in the development of static electric charges of opposite polarity at the opposite ends of the crystal. If this charge is allowed to collect on the faces of the crystal then the performance of the laser will be affected. In normal atmospheres some leakage of the charge will occur. However, Q-switched lasers of the type described above are often sealed into an enclosure with an extremely dry atmosphere, and this prevents charge leaking.
.Iadd.It is possible simply to conduct the charge away from the face. This requires the formation on the end face of an optically-transparent but electrically-conducting layer which is connected to ground. FIG. 3 shows such an arrangement. The main problem with this technique is that the conducting layer 60 interferes with the passage of optical radiation through the end faces of the crystal. Equally, it may be damaged by the power of the optical radiation passing through it. .Iaddend.
It is an object of he invention to provide an optical modulator in which the adverse results of the pyroelectric effect are eliminated,
According to the present invention there is provided and optical modulator which includes a crystal of a material exhibiting the pyroelectric effect and means for dissipating any electric charge built up on the optical faces of the crystal,
The invention will now be described with reference to the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a common form of Q-switched laser, incorporating an optical modulator;
FIG. 2 is a perspective view of an optical modulator crystal; .[.and.].
.Iadd.FIG. 3 diagrammatically illustrates a prior art method, as above described, of dissipating accumulated charge on the faces; and .Iaddend.
FIGS. .[.3.]. .Iadd.4 .Iaddend.to 7 are schematic diagrams illustrating different embodiments of the invention.
Referring now to FIG. 1, .[.as.]. .Iadd.a .Iaddend.common form of Q-switched laser includes a rod 10 of laser active material, such as Neodymium-YAG together with an associated flash tube 11 for optically pumping the active material. Two porro prisms 12 and 13 define the optical cavity of the laser which also includes a polariser 14 and a Q-switch 15. The Q-switch is a crystal of a material such as Lithium Niobate and is provided with two electrodes 16 connected to a modulating power supply 17. The optical components are arranged along an optical axis 18, with the electrodes 16 on the crystal 15 arranged on opposite sides of the optical axis.
The Q-switch 15 comprises a crystal of material formed into a block and fastened in an electrically insulating housing 20 as shown in FIG. 2. The end faces 21 are those through which the laser radiation passes. It is on these faces in particular that a static electric charge may build up due to the pyroelectric effect. Removal of this static electric charge may be achieved basically in two ways. One involves neutralising the charge in some way, whilst the other involves conducting the charge away from the faces of the crystal. The polarity of the charge depends upon whether the temperature of the crystal is increasing or decreasing.
FIG. .[.3.]. .Iadd.4 .Iaddend.illustrates one technique which may be used to neutralise any static charge on the end faces of the crystal. A source of ions is provided adjacent to each face by emission from point electrodes 30 adjacent to each face but away from the path of any optical radiation. A high-voltage power supply 31 is connected to the electrodes. When the supply 31 is energised a stream of ions is emitted by each electrode 30 and these ions of opposite charge to that on the adjacent face of the crystal will be attracted to that face to neutralise the charge caused by the pyroelectric effect. Since the polarity of the charge on a face may vary the power supply 31 should preferably be a high voltage alternating current supply.
As an alternative to the arrangement of FIG. .[.3.]. .Iadd.4 .Iaddend.the neutralising ions may be produced by a spark discharge. This may use the arrangement shown in FIG. .[.4.]. .Iadd.5 .Iaddend.in which a pair of electrodes 40 is provided, forming a spark gap adjacent to each face, again well clear of the path of optical radiation. One electrode of each pair will be, conveniently, connected to ground. The high voltage power supply 31, which may be a direct-current supply, may be triggered to produce a spark between each pair of electrodes. This produces a cloud of both positive and negative ions, the appropriate ones of which will neutralise the charge on the face of the crystal.
The techniques described above with reference to FIGS. .[.3 and 4.]. .Iadd.4 and 5 .Iaddend.might best be used before the laser is activated since the ions produced by the electric discharges may interact with the modulating electrodes on the sides of the Q-switching crystal.
A technique which does not require a high-voltage power supply to produce neutralising ions is shown schematically in FIG. .[.5..]. .Iadd.6. .Iaddend.This involves placing near to each end face of the Q-switching crystal a small radioactive source 50. Each of these sources will emit ionising radiation towards the adjacent face of the crystal. Such radiation will be arrested both by the atmosphere in front of the end faces and by the faces themselves, with the generation of ion pairs, some of which will neutralise the static charge. This process is continuous as it is not practically possible to control the emission of alpha particles from the source.
As an alternative to producing ions to neutralise any charge built up on the end faces of the crystal, .[.it is possible simply to conduct the charge away from the face. This requires the formation on the end face of an optically-transparent but electrically-conducting layer which is connected to ground. FIG. 6 shows such an arrangement. The main problem with this technique is that the conducting layer 60 must not interfere with the passage of optical radiation through the end faces of the crystal. Equally, it must not be damaged by the power of the optical radiation passing through it..].
.[.As an alternative to providing a conducting layer on each face of the crystal.]. it is possible to remove the accumulated charge intermittently by wiping the face with an electrically-conducting material. FIG. 7 illustrates an arrangement using an electrically conducting blade 70 connected to ground and wiped over the face 21 of the crystal by a motor 71. Other mechanical arrangements could be used.
The optical components of a Q-switched laser are sometimes enclosed in a sealed container so that the atmosphere may be controlled, particularly to prevent misting of optical surfaces during conditions where condensation might occur. Any of the charge-removal techniques described above may be used inside such a sealed container. The techniques may also be used on Q-switching crystals of other materials than Lithium Niobate which exhibit the pyroelectric effect.
The optical modulator may be used in other applications than Q-switched lasers, and all the techniques described above are applicable to such applications.
Claims (10)
1. An optical modulator of the Q-switch type comprising:
.Iadd.an optical path; .Iaddend.
a crystal of a material which exhibits the pyroelectric effect .[.and.]. .Iadd.disposed on said optical path, said crystal .Iaddend.having two opposed optical faces through which laser radiation may pass along .[.a.]. .Iadd.said optical .Iaddend.path;
means to apply an electric field to the crystal .[.ransverse.]. .Iadd.transverse .Iaddend.to said path in order to switch said modulator; and
charge-dissipating means for dissipating any static electric charge built up on the two opposed optical faces of the crystal due to the pyroelectric effect.Iadd., said charge dissipating means being disposed adjacent to said optical faces but being disposed so as normally to lie outside of said path. .Iaddend.
2. A modulator as claimed in claim 1 which includes ionising means located adjacent to the optical faces of the crystal and operable to generate ions of opposite polarity to the charge on said optical face.
3. A modulator as claimed in claim 2 in which the ionising means comprise a point electrode connected to a high-voltage power supply.
4. A modulator as claimed in claim 3 in which the high-voltage power supply generates an alternating voltage for application to the point electrodes.
5. A modulator as claimed in claim 2 in which the ionising means comprise a spark gap.
6. A modulator as claimed in claim 2 in which the ionising means comprise a radioactive source capable of emitting ionising radiation towards said optical faces. .[.
7. A modulator as claimed in claim 1 in which the optical faces of the crystal are provided with a layer of electrically-conducting material connected to the ground..].
8. A modulator as claimed in claim 1 in which each optical end face is provided with an electrically-conductive wiper movable across the said face and connected to ground.
9. A modulator as claimed in claim 1 which forms the Q-switch of a Q-switched laser. .Iadd.10. An optical modulator of the Q-switch type comprising:
a crystal of a material which exhibits the pyroelectric effect and having two opposed optical faces through which laser radiation may pass along a path;
means to apply an electric field to the crystal transverse to said path in order to switch said modulator;
charge-dissipating means for dissipating any static electric charge built up on the two opposed optical faces of the crystal due to the pyroelectric effect; and
a radioactive source located adjacent to the optical faces, said radio active source being capable of emitting ionising radiation towards said optical faces to generate ions of opposite polarity to any static charge
thereon whereby to dissipate the static charge. .Iaddend. .Iadd.11. An optical modulator of the Q-switch type comprising:
a crystal of a material which exhibits the pyroelectric effect and having two opposed optical faces through which laser radiation may pass along a path; means to apply an electric field to the crystal transverse to said path in order to switch said modulator; and
charge-dissipating means for dissipating any static electric charge built up on the two opposed optical faces of the crystal due to the pyroelectric effect, which includes ionising means located adjacent to the optical faces of the crystal and operable to generate ions of opposite polarity to the charge on said optical face. .Iaddend. .Iadd.12. An optical modulator of the Q-switch type comprising:
a crystal of a material which exhibits the pyroelectric effect and having two opposed optical faces through which laser radiation may pass along a path; means to apply an electric field to the crystal transverse to said path in order to switch said modulator; and
charge-dissipating means for dissipating any static electric charge built up on the two opposed optical faces of the crystal due to the pyroelectric effect, which includes ionising means located adjacent to the optical faces of the crystal and operable to generate ions of opposite polarity to the charge on said optical face, in which the ionising means comprise a radioactive source capable of emitting ionising radiation towards said optical faces. .Iaddend.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/070,251 USRE35240E (en) | 1987-09-09 | 1993-06-02 | Optical modulators |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8721152A GB2209609B (en) | 1987-09-09 | 1987-09-09 | Optical modulators |
| GB8721152 | 1987-09-09 | ||
| US07/235,156 US4884044A (en) | 1987-09-09 | 1988-08-23 | Optical modulators |
| US08/070,251 USRE35240E (en) | 1987-09-09 | 1993-06-02 | Optical modulators |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US07/235,156 Reissue US4884044A (en) | 1987-09-09 | 1988-08-23 | Optical modulators |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| USRE35240E true USRE35240E (en) | 1996-05-14 |
Family
ID=10623481
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US07/235,156 Ceased US4884044A (en) | 1987-09-09 | 1988-08-23 | Optical modulators |
| US08/070,251 Expired - Lifetime USRE35240E (en) | 1987-09-09 | 1993-06-02 | Optical modulators |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US07/235,156 Ceased US4884044A (en) | 1987-09-09 | 1988-08-23 | Optical modulators |
Country Status (5)
| Country | Link |
|---|---|
| US (2) | US4884044A (en) |
| DE (1) | DE3829747C2 (en) |
| FR (1) | FR2620277B1 (en) |
| GB (1) | GB2209609B (en) |
| IT (1) | IT1224729B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5796470A (en) * | 1995-02-28 | 1998-08-18 | Canon Kabushiki Kaisha | Frequency shifter and optical displacement measuring apparatus using the frequency shifter |
| US20110110386A1 (en) * | 2009-11-11 | 2011-05-12 | Flir Systems, Inc. | Q-Switched Laser with Passive Discharge Assembly |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5339369A (en) * | 1992-10-23 | 1994-08-16 | General Microwave Israel Corporation | High-speed external modulator |
| US5455876A (en) * | 1992-10-23 | 1995-10-03 | General Microwave Israel Corporation | High-speed external integrated optical modulator |
| WO1996029765A1 (en) * | 1995-03-23 | 1996-09-26 | Coherent, Inc. | Prism folded laser cavity with controlled intracavity beam polarization |
| JP2001004965A (en) * | 1999-06-18 | 2001-01-12 | Ando Electric Co Ltd | E/o switch controller and control method for e/o switch |
| JP4154477B2 (en) * | 2001-12-28 | 2008-09-24 | 独立行政法人情報通信研究機構 | Laser oscillator |
| US20080002751A1 (en) * | 2005-08-10 | 2008-01-03 | Gongxue Hua | High damage threshold Q-switched CO2 laser |
| US8488635B2 (en) * | 2010-08-17 | 2013-07-16 | The United States Of America As Represented By The Secretary Of The Army | UV illumination for mitigation of cold temperature pyroelectric effects in lithium niobate |
| US9470912B2 (en) * | 2014-01-17 | 2016-10-18 | Gooch And Housego Plc | Chemically reduced lithium compound-based Q-switch |
| US10983372B2 (en) * | 2017-07-14 | 2021-04-20 | Redlen Technologies, Inc. | Fast-switching electro-optic modulators and method of making the same |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3311845A (en) * | 1963-06-10 | 1967-03-28 | American Optical Corp | Q-switching apparatus for a laser device |
| US3445826A (en) * | 1966-01-03 | 1969-05-20 | Ibm | Electro-optic storage device |
| US3713032A (en) * | 1970-10-01 | 1973-01-23 | Westinghouse Electric Corp | Q-switching laser system having electronically controlled output coupling |
| US3820038A (en) * | 1973-02-09 | 1974-06-25 | Atomic Energy Commission | Method and apparatus for producing isolated laser pulses having a fast rise time |
| US3965439A (en) * | 1974-12-03 | 1976-06-22 | The United States Of America As Represented By The Secretary Of The Army | Electrooptic-Q-switching system for a laser |
| JPS568227A (en) * | 1979-06-29 | 1981-01-28 | Kanegafuchi Chem Ind Co Ltd | Continuous preparation of laminate covered by metal foil |
| JPS57196166A (en) * | 1981-05-28 | 1982-12-02 | Matsushita Electric Ind Co Ltd | Voltage measurement device |
| US4375684A (en) * | 1980-07-28 | 1983-03-01 | Jersey Nuclear-Avco Isotopes, Inc. | Laser mode locking, Q-switching and dumping system |
| EP0167143A2 (en) * | 1984-07-04 | 1986-01-08 | Hitachi, Ltd. | Method of driving optical switch element |
| US4628222A (en) * | 1980-11-17 | 1986-12-09 | National Research Development Corporation | Protection of saw devices comprising metallized regions on dielectric substrates |
| US4739507A (en) * | 1984-11-26 | 1988-04-19 | Board Of Trustees, Stanford University | Diode end pumped laser and harmonic generator using same |
-
1987
- 1987-09-09 GB GB8721152A patent/GB2209609B/en not_active Expired - Lifetime
-
1988
- 1988-08-23 US US07/235,156 patent/US4884044A/en not_active Ceased
- 1988-09-01 DE DE3829747A patent/DE3829747C2/en not_active Expired - Fee Related
- 1988-09-06 IT IT8848321A patent/IT1224729B/en active
- 1988-09-07 FR FR8811688A patent/FR2620277B1/en not_active Expired - Fee Related
-
1993
- 1993-06-02 US US08/070,251 patent/USRE35240E/en not_active Expired - Lifetime
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3311845A (en) * | 1963-06-10 | 1967-03-28 | American Optical Corp | Q-switching apparatus for a laser device |
| US3445826A (en) * | 1966-01-03 | 1969-05-20 | Ibm | Electro-optic storage device |
| US3713032A (en) * | 1970-10-01 | 1973-01-23 | Westinghouse Electric Corp | Q-switching laser system having electronically controlled output coupling |
| US3820038A (en) * | 1973-02-09 | 1974-06-25 | Atomic Energy Commission | Method and apparatus for producing isolated laser pulses having a fast rise time |
| US3965439A (en) * | 1974-12-03 | 1976-06-22 | The United States Of America As Represented By The Secretary Of The Army | Electrooptic-Q-switching system for a laser |
| JPS568227A (en) * | 1979-06-29 | 1981-01-28 | Kanegafuchi Chem Ind Co Ltd | Continuous preparation of laminate covered by metal foil |
| US4375684A (en) * | 1980-07-28 | 1983-03-01 | Jersey Nuclear-Avco Isotopes, Inc. | Laser mode locking, Q-switching and dumping system |
| US4628222A (en) * | 1980-11-17 | 1986-12-09 | National Research Development Corporation | Protection of saw devices comprising metallized regions on dielectric substrates |
| JPS57196166A (en) * | 1981-05-28 | 1982-12-02 | Matsushita Electric Ind Co Ltd | Voltage measurement device |
| EP0167143A2 (en) * | 1984-07-04 | 1986-01-08 | Hitachi, Ltd. | Method of driving optical switch element |
| US4739507A (en) * | 1984-11-26 | 1988-04-19 | Board Of Trustees, Stanford University | Diode end pumped laser and harmonic generator using same |
Non-Patent Citations (1)
| Title |
|---|
| French search report. * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5796470A (en) * | 1995-02-28 | 1998-08-18 | Canon Kabushiki Kaisha | Frequency shifter and optical displacement measuring apparatus using the frequency shifter |
| US20110110386A1 (en) * | 2009-11-11 | 2011-05-12 | Flir Systems, Inc. | Q-Switched Laser with Passive Discharge Assembly |
| US7970031B2 (en) | 2009-11-11 | 2011-06-28 | Flir Systems, Inc. | Q-switched laser with passive discharge assembly |
Also Published As
| Publication number | Publication date |
|---|---|
| AU615941B2 (en) | 1991-10-17 |
| GB8721152D0 (en) | 1987-10-14 |
| GB2209609A (en) | 1989-05-17 |
| DE3829747C2 (en) | 1999-05-06 |
| FR2620277A1 (en) | 1989-03-10 |
| DE3829747A1 (en) | 1989-03-23 |
| IT1224729B (en) | 1990-10-18 |
| AU2187188A (en) | 1989-03-09 |
| US4884044A (en) | 1989-11-28 |
| IT8848321A0 (en) | 1988-09-06 |
| FR2620277B1 (en) | 1995-03-17 |
| GB2209609B (en) | 1991-06-26 |
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