CA1309155C - Ring laser - Google Patents
Ring laserInfo
- Publication number
- CA1309155C CA1309155C CA000527771A CA527771A CA1309155C CA 1309155 C CA1309155 C CA 1309155C CA 000527771 A CA000527771 A CA 000527771A CA 527771 A CA527771 A CA 527771A CA 1309155 C CA1309155 C CA 1309155C
- Authority
- CA
- Canada
- Prior art keywords
- ring laser
- passage
- block
- electrodes
- passages
- 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
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/58—Turn-sensitive devices without moving masses
- G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
- G01C19/66—Ring laser gyrometers
- G01C19/661—Ring laser gyrometers details
-
- 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
- H01S3/097—Processes or apparatus for excitation, e.g. pumping by gas discharge of a gas laser
- H01S3/0975—Processes or apparatus for excitation, e.g. pumping by gas discharge of a gas laser using inductive or capacitive excitation
-
- 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
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/081—Construction or shape of optical resonators or components thereof comprising three or more reflectors
- H01S3/083—Ring lasers
- H01S3/0835—Gas ring lasers
Abstract
Edin 643/DNB
ABSTRACT
RING LASER
A ring laser comprises a block (10) of dielectric material in which are formed a number of passages (11) defining a closed polygonal path. A gaseous active medium which are closed by mirrors (12). Two electrodes (16) are arranged external to the passage parallel to and on opposite sides of part or all of at least one of the passages (11). In operation the electrodes (10) are capacitively coupled to the gaseous active medium to produce an electric discharge therein transverse to the direction of the passage by the application to electrodes (16) of a high-frequency alternating voltage.
ABSTRACT
RING LASER
A ring laser comprises a block (10) of dielectric material in which are formed a number of passages (11) defining a closed polygonal path. A gaseous active medium which are closed by mirrors (12). Two electrodes (16) are arranged external to the passage parallel to and on opposite sides of part or all of at least one of the passages (11). In operation the electrodes (10) are capacitively coupled to the gaseous active medium to produce an electric discharge therein transverse to the direction of the passage by the application to electrodes (16) of a high-frequency alternating voltage.
Description
-^~ 130ql55 1 - 1 3 0 9 1 5~in 643/DNB
RING LASER
Ring lasers are used as angular rate sensors primarily, though not exclusively in inertial navigation applications.
Basically a ring laser comprises two laser beams which travel in opposite directions around the same closed loop path. Commonly the path is generally triangular in form. Rotation rates about an axis perpendicular to the plane of the ring laser resonant cavity are measured by detecting the beat frequency which occurs due to a ~requency difference between the counterrotating beams resulting from the rotation.
1~ A commonly-used form of ring laser designed ~or such a purpose is described in US Patent No. 3,390,606 and its British equivalent No. 1,142,962. The ring laser shown therein comprises a solid block of dielectric mater-ial in which three passages have been formed to provide a triangular passage through the block.
Mirrors are provided at the points where pairs of passages intersect, and one of the mirrors also forms part of the detection means. The passages are filled with a suitable gas or gas mixture and an electric discharge is produced in the gas between anode and cathode electrocles which extend into the lasing gas~
Such an arrangement for producing an electric discharge in the gas has a number of disadvantages. One of these has been the need to provide an excitation power supply producing a dc running voltage of between 500 and 1,000 volts, with a striking voltage of up to 3,000 volts. Such a power supply has of necessity been large in size. In addition the presence of anode an~ cathode electrodes causes sputtering and gas flow effects. Other problems also occur.
It is an object of the present invention to provide a ring laser in which the above problems are avoided.
According to the present inventlon there is provided a ring laser which includes a block Ol dielectric material having formed therein at least one pas~age d~ ;ing a closed polygonal path lying in one plane within the block, a yaseous active medium contained within the said passage, and two electrodes arranged external to the passage parallel to and on opposite sides of at .
.. ~
1 309 1 55 26s82-4 least part of ~aid passage and being, in use, capacitively coupled to the gaseous active medi~lm to produce an electric discharye therein transverse to ~he direction of the passage by the application of a high-frequency alternating voltage between said two electrodes.
The invention will now be described with reference to the accompanying drawings, in which:-Figure 1 shows a simplified plan view of a ring laseraccording to a first embodiment of the invention;
Figure 2 shows a part-sectioned side view of ~he ring laser of Figure 1 î
Figure 3 shows a circuit diagram of a power supply suita~le for the ring laser of Fi.gure 1; and Fiyure 4 shows a plan view according to a second embodiment of the invention.
Referring now to Flgures 1 and 2 the ring laser is made from a block 10 of a dielectric material such as a glass-ceramic materlal havin~ hlgh thermal stability. Conveniently the block 10 may be in the ~hape of a truncated trlangle as shown in Figure 1. 20 Three passages 11 are bored through the block 10 parallel to the three sides of the trianyle. The three passages emerge through the truncated corners O:e the block. Each of these corners carries a mirror 12 mounted so that laser radiatlon emerging from one passage is reflected along the next passage so that the radiation follows a closed path through the passages. Two of the mirrors may be fully re~lecting whilst the third is partially transmitting and is associated with a detector 13 which produces an electrical output on a cable 14.
As shown in Figures 1 and 2 two grooves 15 are machined into the block respectively above and below one of the passages 11. At the botto~ of each of the grooves 15 is located a metal electrode 16 to which may be applied a high-frequency alternating excitation voltage from a suitable power supply.
In the centre of block 10 may be located a dither mechanism, represented by the reference 17, which is able to oscillate the block through a small angle about an axis 18, this . . ~ .
-"` 1 3~q 1 55 - 3 - Edin 643/DNB
being the axis about which the ring laser is able to sense angular movements. Such dither mechanisms are well-known and need not be described here.
In operation, the application of a suitable high-frequency alternating voltage between the two electrodes 16 causes excitation of the laser gaseous active medium, usually a Helium-Neon mixture, contained in the passage 11 located between the electrodes. This excitation is transverse to the direction of the passage 11 and produces an electric discharge in the gas, resulting in laser action taking place. This produces laser beams travelling in both directions around the closed path defined by the passages 11 and the mirrors 12 The use of a transverse high-frequency alterna~ing voltage to excite the laser has a number of benefits. It is not necessary to insert electrodes into the passages 11, and hence the problems caused by such electrodes are avoided.
Transverse capacitive coupling of high-frequency alterna^ting power into the discharge through the glass-ceramic walls between the electrodes allows a much reduced drive voltage to be used compared with known longitudinally excited ring lasers.
Typically, ~or a ring laser having a bore of 3mm the drive voltage may be of the order of 5-10 volts at a frequency of between lOMHZ
and 5GHZ. Capacitive ballasting exists so that no ballast resistors are required and hence the power consumption is much less. The frequency range referred to lies within the main communications band and hence components are readily available to enable small low cost power supplies to be produced. A power supply suitable for the purpose is shown in Figure 3.
As shown in Figure 3 the power supply circuit is very simple, comprising a radio-frequency oscillator 30 operable to produce an alternating signal at the required frequency. This signal is amplified by amplifier 31 to provide the necessary voltage level and is coupled to the ring laser shown schematical1y at 32 by an impedance matcliing n~work 33.
The laser illustrated in Figure 1 has electrodes associated with one of the three passages 11 formed in the block.
Excitation may be provided on either or both of the other passages ~ 1 309 1 55 - 4 - Edin 643/DNB
if necessary, depending upon the bore of the passage and gain required for satisfactory operation. Figure 4 show a plan view of 15 a ring laser having two pairs of electrodes.
The ring laser is not operated as a waveguide laser.
The electrodes need not necessarily be located in grooves in the dielectric material, though this is one way of reducing the thickness of material between the electrodes and the passage. I~
a material of sufficient strength was available the block could be made sufficiently thin for the electrodes to be formed on its surface. Alternatively the thickness of the material may be reduced by using other configurations.
A number of other advantages arise from the use of transverse high-frequency alternating excitation of the laser.
The discharge in the gas occurs substantially between the two electrodes, unlike the dc longitudinally-excited ring laser. This means that the discharge occurs well away from the mirrors avoiding the risk of mirror damage due to ultra-violet radiation or ion bombardment. Construction is simpler than with the dc-excited ring laser leading to a lower manufacturing cost. The only vacuum seals required are for the three mirror ports and a gas fill port. Glass-ceramic materials are particularly suitable as they remain stable, having zero or very small coefficients of thermal expansion, over a very wide temperature range, from -50 C to 400 C. ~;
Various examples of such materials are known by the trade names Zerodur, Cervit and ULE.
' .
,, , . ~
RING LASER
Ring lasers are used as angular rate sensors primarily, though not exclusively in inertial navigation applications.
Basically a ring laser comprises two laser beams which travel in opposite directions around the same closed loop path. Commonly the path is generally triangular in form. Rotation rates about an axis perpendicular to the plane of the ring laser resonant cavity are measured by detecting the beat frequency which occurs due to a ~requency difference between the counterrotating beams resulting from the rotation.
1~ A commonly-used form of ring laser designed ~or such a purpose is described in US Patent No. 3,390,606 and its British equivalent No. 1,142,962. The ring laser shown therein comprises a solid block of dielectric mater-ial in which three passages have been formed to provide a triangular passage through the block.
Mirrors are provided at the points where pairs of passages intersect, and one of the mirrors also forms part of the detection means. The passages are filled with a suitable gas or gas mixture and an electric discharge is produced in the gas between anode and cathode electrocles which extend into the lasing gas~
Such an arrangement for producing an electric discharge in the gas has a number of disadvantages. One of these has been the need to provide an excitation power supply producing a dc running voltage of between 500 and 1,000 volts, with a striking voltage of up to 3,000 volts. Such a power supply has of necessity been large in size. In addition the presence of anode an~ cathode electrodes causes sputtering and gas flow effects. Other problems also occur.
It is an object of the present invention to provide a ring laser in which the above problems are avoided.
According to the present inventlon there is provided a ring laser which includes a block Ol dielectric material having formed therein at least one pas~age d~ ;ing a closed polygonal path lying in one plane within the block, a yaseous active medium contained within the said passage, and two electrodes arranged external to the passage parallel to and on opposite sides of at .
.. ~
1 309 1 55 26s82-4 least part of ~aid passage and being, in use, capacitively coupled to the gaseous active medi~lm to produce an electric discharye therein transverse to ~he direction of the passage by the application of a high-frequency alternating voltage between said two electrodes.
The invention will now be described with reference to the accompanying drawings, in which:-Figure 1 shows a simplified plan view of a ring laseraccording to a first embodiment of the invention;
Figure 2 shows a part-sectioned side view of ~he ring laser of Figure 1 î
Figure 3 shows a circuit diagram of a power supply suita~le for the ring laser of Fi.gure 1; and Fiyure 4 shows a plan view according to a second embodiment of the invention.
Referring now to Flgures 1 and 2 the ring laser is made from a block 10 of a dielectric material such as a glass-ceramic materlal havin~ hlgh thermal stability. Conveniently the block 10 may be in the ~hape of a truncated trlangle as shown in Figure 1. 20 Three passages 11 are bored through the block 10 parallel to the three sides of the trianyle. The three passages emerge through the truncated corners O:e the block. Each of these corners carries a mirror 12 mounted so that laser radiatlon emerging from one passage is reflected along the next passage so that the radiation follows a closed path through the passages. Two of the mirrors may be fully re~lecting whilst the third is partially transmitting and is associated with a detector 13 which produces an electrical output on a cable 14.
As shown in Figures 1 and 2 two grooves 15 are machined into the block respectively above and below one of the passages 11. At the botto~ of each of the grooves 15 is located a metal electrode 16 to which may be applied a high-frequency alternating excitation voltage from a suitable power supply.
In the centre of block 10 may be located a dither mechanism, represented by the reference 17, which is able to oscillate the block through a small angle about an axis 18, this . . ~ .
-"` 1 3~q 1 55 - 3 - Edin 643/DNB
being the axis about which the ring laser is able to sense angular movements. Such dither mechanisms are well-known and need not be described here.
In operation, the application of a suitable high-frequency alternating voltage between the two electrodes 16 causes excitation of the laser gaseous active medium, usually a Helium-Neon mixture, contained in the passage 11 located between the electrodes. This excitation is transverse to the direction of the passage 11 and produces an electric discharge in the gas, resulting in laser action taking place. This produces laser beams travelling in both directions around the closed path defined by the passages 11 and the mirrors 12 The use of a transverse high-frequency alterna~ing voltage to excite the laser has a number of benefits. It is not necessary to insert electrodes into the passages 11, and hence the problems caused by such electrodes are avoided.
Transverse capacitive coupling of high-frequency alterna^ting power into the discharge through the glass-ceramic walls between the electrodes allows a much reduced drive voltage to be used compared with known longitudinally excited ring lasers.
Typically, ~or a ring laser having a bore of 3mm the drive voltage may be of the order of 5-10 volts at a frequency of between lOMHZ
and 5GHZ. Capacitive ballasting exists so that no ballast resistors are required and hence the power consumption is much less. The frequency range referred to lies within the main communications band and hence components are readily available to enable small low cost power supplies to be produced. A power supply suitable for the purpose is shown in Figure 3.
As shown in Figure 3 the power supply circuit is very simple, comprising a radio-frequency oscillator 30 operable to produce an alternating signal at the required frequency. This signal is amplified by amplifier 31 to provide the necessary voltage level and is coupled to the ring laser shown schematical1y at 32 by an impedance matcliing n~work 33.
The laser illustrated in Figure 1 has electrodes associated with one of the three passages 11 formed in the block.
Excitation may be provided on either or both of the other passages ~ 1 309 1 55 - 4 - Edin 643/DNB
if necessary, depending upon the bore of the passage and gain required for satisfactory operation. Figure 4 show a plan view of 15 a ring laser having two pairs of electrodes.
The ring laser is not operated as a waveguide laser.
The electrodes need not necessarily be located in grooves in the dielectric material, though this is one way of reducing the thickness of material between the electrodes and the passage. I~
a material of sufficient strength was available the block could be made sufficiently thin for the electrodes to be formed on its surface. Alternatively the thickness of the material may be reduced by using other configurations.
A number of other advantages arise from the use of transverse high-frequency alternating excitation of the laser.
The discharge in the gas occurs substantially between the two electrodes, unlike the dc longitudinally-excited ring laser. This means that the discharge occurs well away from the mirrors avoiding the risk of mirror damage due to ultra-violet radiation or ion bombardment. Construction is simpler than with the dc-excited ring laser leading to a lower manufacturing cost. The only vacuum seals required are for the three mirror ports and a gas fill port. Glass-ceramic materials are particularly suitable as they remain stable, having zero or very small coefficients of thermal expansion, over a very wide temperature range, from -50 C to 400 C. ~;
Various examples of such materials are known by the trade names Zerodur, Cervit and ULE.
' .
,, , . ~
Claims (8)
1. A ring laser which includes a block of dielectric material having formed therein at least one passage defining a closed polygonal path lying in one plane within the block, a gaseous active medium contained within the said passage, and two electrodes arranged external to the passage parallel to and on opposite sides of at least part of said passage and being, in use, capacitively coupled to the gaseous active medium to produce an electric discharge therein transverse to the direction of the passage by the application of a high-frequency alternating voltage between said two electrodes.
2. A ring laser as claimed in Claim 1 in which the block of dielectric material contains three passages defining a substantially triangular closed path.
3. A ring laser as claimed in Claim 1 in which the said two electrodes are associated with one only of said passages.
4. A ring laser as claimed in Claim 1 in which one at least of said two electrodes is located in a groove extending from the surface of the block of dielectric material towards the said passage.
5. A ring laser as claimed in Claim 2 in which the said block carries three mirrors each positioned at the intersection of two of said passages so as to reflect laser radiation emerging from on passage into the adjacent passage.
6. A ring laser as claimed in Claim 1 in which the block of dielectric material is made from a glass-ceramic material.
7. A ring laser as claimed in Claim 1 in which the gaseous active medium is a mixture of Helium and Neon.
8. A ring laser as claimed in Claim 1 in which the frequency of the high-frequency alternating voltage is in the range from 10 MHz to 5GHZ.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB86.01741 | 1986-01-24 | ||
| GB8601741A GB2185846B (en) | 1986-01-24 | 1986-01-24 | Ring laser |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1309155C true CA1309155C (en) | 1992-10-20 |
Family
ID=10591887
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000527771A Expired - Lifetime CA1309155C (en) | 1986-01-24 | 1987-01-21 | Ring laser |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS62217683A (en) |
| CA (1) | CA1309155C (en) |
| DE (1) | DE3700844A1 (en) |
| FR (1) | FR2593650B1 (en) |
| GB (1) | GB2185846B (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5196905A (en) * | 1988-06-22 | 1993-03-23 | Litton Systems, Inc. | Radio frequency excited ring laser gyroscope |
| GB8728829D0 (en) * | 1987-12-10 | 1988-01-27 | British Aerospace | Ring laser gyroscopes |
| GB8728831D0 (en) * | 1987-12-10 | 1988-01-27 | British Aerospace | Ring laser gyroscopes |
| CA1320557C (en) * | 1988-06-22 | 1993-07-20 | Litton Systems, Inc. | Radio frequency excited ring laser gyroscope |
| GB2227878B (en) * | 1989-02-03 | 1992-04-22 | Ferranti Int Signal | Ring laser gyroscope |
| DE3905549A1 (en) * | 1989-02-23 | 1990-08-30 | Marinescu Marlene | Gas-discharge arrangement |
| US5056102A (en) * | 1989-05-15 | 1991-10-08 | Honeywell Inc. | Getter assembly |
| CA2022329C (en) * | 1989-12-26 | 1995-03-28 | Bruce C. Grover | Dual helix rf discharge with single driver for ring laser gyroscope |
| DE4017188A1 (en) * | 1990-05-29 | 1991-12-05 | Bodenseewerk Geraetetech | GAS RING LASER |
| DE4124407A1 (en) * | 1991-07-23 | 1993-01-28 | Wb Laser Wegmann Baasel Laser | Ring laser with polygonal beam path in resonator - uses reflection and output mirrors and deflection elements with two or more mutually offset polygonal beam paths to achieve high output power |
| US5381436A (en) * | 1993-05-28 | 1995-01-10 | Honeywell, Inc. | Ring laser gyro employing radio frequency for pumping of gain medium |
| US9759565B2 (en) * | 2015-01-15 | 2017-09-12 | Honeywell International Inc. | Radio frequency ring laser gyroscope including a multiple electrode system and an impedance matching circuit |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3390606A (en) * | 1965-03-01 | 1968-07-02 | Honeywell Inc | Control apparatus |
| FR2041638A5 (en) * | 1969-05-09 | 1971-01-29 | Comp Generale Electricite | |
| US3772611A (en) * | 1971-12-27 | 1973-11-13 | Bell Telephone Labor Inc | Waveguide gas laser devices |
| GB1594047A (en) * | 1978-05-31 | 1981-07-30 | Litton Systems Inc | Ring laser gyroscopes |
| JPS57186381A (en) * | 1981-05-11 | 1982-11-16 | Mitsubishi Electric Corp | Silent discharge type laser |
| US4464760A (en) * | 1982-04-20 | 1984-08-07 | Sutter Jr Leroy V | Elongated chambers for use in combination with a transversely excited gas laser |
| FR2530087B1 (en) * | 1982-07-09 | 1986-02-14 | Telecommunications Sa | GAS WAVEGUIDE LASER GENERATOR AND METHOD FOR MANUFACTURING THE WAVEGUIDE |
| US4596018A (en) * | 1983-10-07 | 1986-06-17 | Minnesota Laser Corp. | External electrode transverse high frequency gas discharge laser |
-
1986
- 1986-01-24 GB GB8601741A patent/GB2185846B/en not_active Expired
-
1987
- 1987-01-14 DE DE19873700844 patent/DE3700844A1/en not_active Withdrawn
- 1987-01-16 FR FR8700428A patent/FR2593650B1/en not_active Expired - Fee Related
- 1987-01-21 CA CA000527771A patent/CA1309155C/en not_active Expired - Lifetime
- 1987-01-22 JP JP1151987A patent/JPS62217683A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2185846B (en) | 1989-12-20 |
| GB2185846A (en) | 1987-07-29 |
| FR2593650B1 (en) | 1993-08-13 |
| FR2593650A1 (en) | 1987-07-31 |
| DE3700844A1 (en) | 1987-07-30 |
| JPS62217683A (en) | 1987-09-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |