WO1992007238A1 - Optical sensing systems - Google Patents
Optical sensing systems Download PDFInfo
- Publication number
- WO1992007238A1 WO1992007238A1 PCT/GB1991/001718 GB9101718W WO9207238A1 WO 1992007238 A1 WO1992007238 A1 WO 1992007238A1 GB 9101718 W GB9101718 W GB 9101718W WO 9207238 A1 WO9207238 A1 WO 9207238A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- light
- optical sensor
- deflected
- modulator
- sensor array
- Prior art date
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
Definitions
- This invention relates to optical sensing systems.
- One type of optical sensing system comprises an optical fibre having a number of discontinuities made along its length.
- a laser is used to provide light which is input or launched in to the fibre and the light is partially reflected at each discontinuity back along the fibre to a detector.
- each section being a sensor and a complete fibre forming an array of sensors.
- arrays have many applications and because their sensitivity is great they can be used as hydrophone arrays, sensing pressure waves in water which may be caused by surface or undersurface vessels.
- Such an optical sensor array is described in United Kingdom patent application no.
- Patent application EP 0299638 describes multiplexing arrangements which use a number of Bragg cells in series.
- the cells when actuated, deflect a beam of light into an associated array or arrays but when not actuated allow the light to pass through to the next cell.
- Figure 1 shows light from a laser 1 is directed to a Bragg cell 2.
- the cell 2 is driven by an r.f. signal applied to input 3, the light is deflected in directions 4, 5, 6 and 7, each direction corresponding to particular frequencies of applied r.f. signal.
- the deflected light is then launched into fibre optic sensor arrays (not shown) .
- the cell 2 When the cell 2 is not driven, the light propagates to the next Bragg cell 8 which in turn may be actuated to reflect the light in a similar manner. Light reflected by discontinuities in each array, passes through the cell 2 to be detected by detector 9.
- an optical sensor system comprising a light source; two or more optical sensor arrays; light deflection means actuable to deflect light received from the light source, from a first direction to a first sensor array; and light recirculating means for returning light propagating in the first direction to the deflection means where it is deflected into a second sensor array.
- Each sensor array may be an arrangement of a number of associated sensors or a single sensor.
- the sensor array may be an optical fibre having discontinuities as previously described or some other type of optical sensor.
- light it is meant electromagnetic radiation which may be visible, infra-red or ultra violet radiation.
- the deflection means may be actuable to divide the incident light beam and recirculated light beam each into two or more resultant beams and to direct the resultant beams substantially simultaneously to respective optical sensor arrays.
- the incident light beam and recirculated light beam would have to be divided into more than two beams, for example, where six sensor arrays are to be driven the beams would each have to be divided into three. Whilst this would allow more optical sensor arrays to be driven it should be noted that the power would also be divided because the optical sensor arrays are driven simultaneously. This would mean that fewer sensors per array could be used.
- the deflection means is, preferably, actuable to deflect the incident light beam sequentially into first and then second optical sensor arrays and the recirculated light beam sequentially into third and fourth optical sensor arrays.
- the light recirculating means comprises at least one reflector.
- the reflector could be a polished metal surface or a layer of silvering applied to glass or plastics material. Whilst it is envisaged that a reflector would be most convenient other means could be used for recirculating the light for instance the light could be recirculated by means of an optical fibre or by means of an optical system which might include a prism or prisms.
- the deflection means may comprise an acousto-optic modulator.
- An acousto-optic modulator requires the application of a radio frequency wave to generate an acoustic wave which propagates through the cell. The effect on a light beam as the acoustic wave passes, is that the light beam is deflected by an amount which is dependent upon the frequency of the acoustic wave which is in turn dependent upon the frequency of the generating wave. If two r.f. pulses are applied simultaneously the light beam is divided in to two deflected beams.
- a method of operating an optical sensing system comprising selectively deflecting light, with a light deflection means, to a first sensor array, recirculating undeflected light to the light deflection means and deflecting the recirculated light to a second optical sensor array.
- the light may be sequentially deflected to first and second optical sensor arrays and the recirculated light sequentially deflected to third and fourth optical sensor arrays.
- more optical sensor arrays may be operated by deflecting the light substantially simultaneously to first and second optical sensor arrays and deflecting the recirculated light substantially simultaneously to third and fourth optical sensor arrays.
- the invention provides a method of operating an optical sensing system comprising: illuminating the acousto-optic modulator with a beam of light; applying a pair of radio frequency pulses to the modulator to form an acoustic wave, such that the wave interacts with the beam to deflect it to a first optical sensor array; and recirculating that light which is not deflected to the modulator such that it can interact with the wave and be deflected to a second optical sensor array.
- the light will therefore have to be recirculated in a way that takes account of the progression of the wave through the modulator in order that the wave and light pass through a region of the modulator at the same time.
- Even more arrays may be driven by conveniently, illuminating an acousto-optic modulator with a beam of light; sequentially applying the first and second pairs of radio frequency pulses to the modulator forming first and second respective acoustic waves in the modulator such that the first wave interacts with the beam to deflect it to a first optical sensor array and the second wave interacts with the beam to deflect it to a second optical sensor array; and recirculating light which is not deflected back to the modulator such that it interacts with the waves, the first
- four or more optical sensor arrays may be driven by illuminating the acousto-optic modulator with a beam of light; applying at least two pairs of radio frequency pulses substantially simultaneously to form an acoustic wave in the modulator such that the wave interacts with the beam to divide the beam and deflect the resulting beams into first and second optical sensor arrays; and recirculating light which is not deflected to the modulator such that it interacts with the wave and is divided into beams which are deflected into third and fourth optical sensor arrays.
- Figure 1 shows the prior art optical sensing system previously described
- Figure 2 shows an optical sensing system constructed in accordance with one aspect of the invention
- Figure 3 shows a second optical sensing system constructed in accordance with one aspect of the invention.
- Figure 4 shows a third optical sensing system constructed in accordance with one aspect of the invention the invention.
- a continuous wave laser light beam 10 is incident on an acousto-optic modulator 11 which is a Bragg cell formed from a crystal of lead molybdate tetra oxide PbMo0 4 .
- the cell 11 is driven by an r.f. pulse pair of frequency F- i -F 2 applied to an input 12 which causes an acoustic wave to be generated and to propagate in the direction of arrow 13 at a velocity of about 3.6 mm per micro second.
- the beam 10 is deflected and then propagates along a light path 14 to be launched into a first optical sensor array 15.
- the beam 10 As the acoustic wave travels away from region a, the beam 10 is no longer deflected but is transmitted along path 16 and reflected along paths 17, 18, 19 and 20 by mirrors 21, 22, 23 and 24.
- the path lengths are chosen such that the recirculated light and the acoustic wave pass through a second region b of the cell 11 at the same time allowing interaction to occur such that the recirculated light is deflected along path 25 to a second optical sensor array 26.
- the beam ceases to be deflected and propagates along path 27.
- This embodiment therefore provides light for the sensor arrays by a time division method.
- a pulse pair F ⁇ F j gives rise to a deflected beam 28.
- a second pulse pair F 3 -F 4 gives rise to a further deflected beam 29.
- the beams 28 and 29 drive optical sensor arrays 30 and 31 respectively.
- the beam 10 is no longer deflected but is reflected by the mirrors and recirculated as in the previous embodiment.
- the recirculated beam gives rise to two further deflected beams 32 and 33 which drive optical sensors 34 and 35 respectively under the action of the same acoustic wave that gave rise to the beams 28 and 29.
- the pulse pairs are applied at the same time and hence the incident beam is split between two arrays halving the power available for each array and consequently allowing fewer sensors to be driven per array than would otherwise be the case.
- This arrangement is a frequency multiplexing arrangement.
- FIG 4 Another embodiment is shown in Figure 4, in which pulse pairs F ⁇ -F z , F 3 -F 4 are applied sequentially. This causes the beam 10 to be deflected to sensor array 30 under the action of the acoustic wave formed by pulse pair F ⁇ -F 2 and then to sensor array 31 under the action of the acoustic wave formed by pulse pair F 3 -F 4 . After the passage of the acoustic waves, the light beam is recirculated as in the previously described embodiments. The recirculated light beam is deflected to sensor array 34 under the action of the acoustic wave formed pulse pair F.,-F 2 and to sensor array 35 under the action of the acoustic wave formed by pulse pair F 3 -F 4 .
- the arrangement is therefore a frequency/time division multiplexing arrangement.
- the light may be recirculated more than once to give an increased multiplexing ratio, that is, even more sensor arrays may be driven from one acousto-optic modulator.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
An optical sensing system comprises a laser (1) which illuminates an acousto-optic modulator (11) with a continuous light beam (10). The modulator (11) is driven by pulse pair (F1-F2) to deflect the beam to optical sensor array (15). When the modulator (11) is not driven, the light beam passes through and is reflected by mirrors (21, 22, 23 and 24) back to the modulator (11) where it is deflected to optical sensor array (26). The arrangement therefore enables one acousto-optic modulator (11) to drive more than one optical sensor array.
Description
Optical Sensing Systems
This invention relates to optical sensing systems.
One type of optical sensing system comprises an optical fibre having a number of discontinuities made along its length. A laser is used to provide light which is input or launched in to the fibre and the light is partially reflected at each discontinuity back along the fibre to a detector.
The way in which the light propagates along the fibre is affected by pressure or other enviromental effect applied to each section between adjacent pairs of discontinuities, each section being a sensor and a complete fibre forming an array of sensors. Such arrays have many applications and because their sensitivity is great they can be used as hydrophone arrays, sensing pressure waves in water which may be caused by surface or undersurface vessels. Such an optical sensor array is described in United Kingdom patent application no.
2126820.
For economy, it is usual to drive a number of sensor arrays from one laser. Patent application EP 0299638 describes multiplexing arrangements which use a number of Bragg cells in series. The cells, when actuated, deflect a
beam of light into an associated array or arrays but when not actuated allow the light to pass through to the next cell. This is shown in Figure 1 in which light from a laser 1 is directed to a Bragg cell 2. When the cell 2 is driven by an r.f. signal applied to input 3, the light is deflected in directions 4, 5, 6 and 7, each direction corresponding to particular frequencies of applied r.f. signal. The deflected light is then launched into fibre optic sensor arrays (not shown) . When the cell 2 is not driven, the light propagates to the next Bragg cell 8 which in turn may be actuated to reflect the light in a similar manner. Light reflected by discontinuities in each array, passes through the cell 2 to be detected by detector 9.
According to the invention there is provided an optical sensor system comprising a light source; two or more optical sensor arrays; light deflection means actuable to deflect light received from the light source, from a first direction to a first sensor array; and light recirculating means for returning light propagating in the first direction to the deflection means where it is deflected into a second sensor array.
By recirculating the light, it is therefore possible to double the number of optical sensor arrays that can be driven
by the light deflection means. Light that is not deflected on its second pass through the light deflection means may also be recirculated in a similar manner allowing even more optical sensor arrays to be used with the one light deflection means. Each sensor array may be an arrangement of a number of associated sensors or a single sensor. The sensor array may be an optical fibre having discontinuities as previously described or some other type of optical sensor. By light it is meant electromagnetic radiation which may be visible, infra-red or ultra violet radiation.
Alternatively, where more sensor arrays are to be driven the deflection means may be actuable to divide the incident light beam and recirculated light beam each into two or more resultant beams and to direct the resultant beams substantially simultaneously to respective optical sensor arrays.
Where more than four sensor arrays are to be driven the incident light beam and recirculated light beam would have to be divided into more than two beams, for example, where six sensor arrays are to be driven the beams would each have to be divided into three. Whilst this would allow more optical sensor arrays to be driven it should be noted that the power would also be divided because the optical sensor arrays are
driven simultaneously. This would mean that fewer sensors per array could be used.
Where it is desired to drive a number of arrays, for example four sensor arrays, and it is also desired to use a large number of sensors per array, the deflection means is, preferably, actuable to deflect the incident light beam sequentially into first and then second optical sensor arrays and the recirculated light beam sequentially into third and fourth optical sensor arrays.
Preferably, the light recirculating means comprises at least one reflector. The reflector could be a polished metal surface or a layer of silvering applied to glass or plastics material. Whilst it is envisaged that a reflector would be most convenient other means could be used for recirculating the light for instance the light could be recirculated by means of an optical fibre or by means of an optical system which might include a prism or prisms.
Conveniently, the deflection means may comprise an acousto-optic modulator. An acousto-optic modulator requires the application of a radio frequency wave to generate an acoustic wave which propagates through the cell. The effect on a light beam as the acoustic wave passes, is that the
light beam is deflected by an amount which is dependent upon the frequency of the acoustic wave which is in turn dependent upon the frequency of the generating wave. If two r.f. pulses are applied simultaneously the light beam is divided in to two deflected beams.
According to a second aspect of the invention, in its broadest sense, there is provided a method of operating an optical sensing system comprising selectively deflecting light, with a light deflection means, to a first sensor array, recirculating undeflected light to the light deflection means and deflecting the recirculated light to a second optical sensor array.
Advantageously, where it is desirable to operate even more optical sensor arrays, the light may be sequentially deflected to first and second optical sensor arrays and the recirculated light sequentially deflected to third and fourth optical sensor arrays.
Alternatively, more optical sensor arrays may be operated by deflecting the light substantially simultaneously to first and second optical sensor arrays and deflecting the recirculated light substantially simultaneously to third and fourth optical sensor arrays.
More specifically the invention provides a method of operating an optical sensing system comprising: illuminating the acousto-optic modulator with a beam of light; applying a pair of radio frequency pulses to the modulator to form an acoustic wave, such that the wave interacts with the beam to deflect it to a first optical sensor array; and recirculating that light which is not deflected to the modulator such that it can interact with the wave and be deflected to a second optical sensor array. The light will therefore have to be recirculated in a way that takes account of the progression of the wave through the modulator in order that the wave and light pass through a region of the modulator at the same time.
Even more arrays may be driven by conveniently, illuminating an acousto-optic modulator with a beam of light; sequentially applying the first and second pairs of radio frequency pulses to the modulator forming first and second respective acoustic waves in the modulator such that the first wave interacts with the beam to deflect it to a first optical sensor array and the second wave interacts with the beam to deflect it to a second optical sensor array; and recirculating light which is not deflected back to the modulator such that it interacts with the waves, the first
S
deflecting in the light to a third optical sensor array and the second wave deflecting the light to a fourth optical sensor array.
Alternatively four or more optical sensor arrays may be driven by illuminating the acousto-optic modulator with a beam of light; applying at least two pairs of radio frequency pulses substantially simultaneously to form an acoustic wave in the modulator such that the wave interacts with the beam to divide the beam and deflect the resulting beams into first and second optical sensor arrays; and recirculating light which is not deflected to the modulator such that it interacts with the wave and is divided into beams which are deflected into third and fourth optical sensor arrays.
Specific embodiments of the invention will now be described by way of example only with reference to the drawings in which:
Figure 1 shows the prior art optical sensing system previously described;
Figure 2 shows an optical sensing system constructed in accordance with one aspect of the invention;
Figure 3 shows a second optical sensing system constructed in accordance with one aspect of the invention; and
Figure 4 shows a third optical sensing system constructed in accordance with one aspect of the invention the invention.
With reference to Figure 2, a continuous wave laser light beam 10 is incident on an acousto-optic modulator 11 which is a Bragg cell formed from a crystal of lead molybdate tetra oxide PbMo04. The cell 11 is driven by an r.f. pulse pair of frequency F-i-F2 applied to an input 12 which causes an acoustic wave to be generated and to propagate in the direction of arrow 13 at a velocity of about 3.6 mm per micro second. As the wave passes through region a of the cell 11 through which the beam 10 propagates, the beam 10 is deflected and then propagates along a light path 14 to be launched into a first optical sensor array 15. As the acoustic wave travels away from region a, the beam 10 is no longer deflected but is transmitted along path 16 and reflected along paths 17, 18, 19 and 20 by mirrors 21, 22, 23 and 24. The path lengths are chosen such that the recirculated light and the acoustic wave pass through a second region b of the cell 11 at the same time allowing
interaction to occur such that the recirculated light is deflected along path 25 to a second optical sensor array 26. Again as the acoustic wave passes through the region b, the beam ceases to be deflected and propagates along path 27. This embodiment therefore provides light for the sensor arrays by a time division method.
By applying pulse pairs of different frequencies and recirculating the light, it is possible for a single acousto-optic modulator to drive even further optical sensor arrays as shown in Figure 3. In this embodiment, a pulse pair F^Fj gives rise to a deflected beam 28. A second pulse pair F3-F4 gives rise to a further deflected beam 29. The beams 28 and 29 drive optical sensor arrays 30 and 31 respectively. As the acoustic wave formed by the pulse pairs passes away from the beam 10, the beam 10 is no longer deflected but is reflected by the mirrors and recirculated as in the previous embodiment. The recirculated beam gives rise to two further deflected beams 32 and 33 which drive optical sensors 34 and 35 respectively under the action of the same acoustic wave that gave rise to the beams 28 and 29. It should be noted that the pulse pairs are applied at the same time and hence the incident beam is split between two arrays halving the power available for each array and consequently allowing fewer sensors to be driven per array than would
otherwise be the case. This arrangement is a frequency multiplexing arrangement.
Another embodiment is shown in Figure 4, in which pulse pairs F^-Fz, F3-F4 are applied sequentially. This causes the beam 10 to be deflected to sensor array 30 under the action of the acoustic wave formed by pulse pair F^-F2 and then to sensor array 31 under the action of the acoustic wave formed by pulse pair F3-F4. After the passage of the acoustic waves, the light beam is recirculated as in the previously described embodiments. The recirculated light beam is deflected to sensor array 34 under the action of the acoustic wave formed pulse pair F.,-F2 and to sensor array 35 under the action of the acoustic wave formed by pulse pair F3-F4. The arrangement is therefore a frequency/time division multiplexing arrangement.
In alternative embodiments of the invention the light may be recirculated more than once to give an increased multiplexing ratio, that is, even more sensor arrays may be driven from one acousto-optic modulator.
Although there have been described above and illustrated in the drawings various embodiments in accordance with the invention, it will be appreciated that the invention is not
limited thereto but encompasses all variations and alternatives within the scope of the claims.
Claims
1. An optical sensing system comprising a light source (1), two or more optical sensor arrays (15,26), light deflection means (11) actuable to deflect light received from the light source (1) , from a first direction to a first sensor array (15) , characterised in light recirculating means for returning light propagating in the first direction to the deflection means (11) where it is deflected into the second sensor array (26) .
2. An optical sensing system as claimed in claim 1, characterised in that the deflection means (11) is actuable to divide an incident light beam (10) and a recirculated light beam each into two or more resultant beams (32,33) and to direct the resultant beams substantially simultaneously to respective optical sensor arrays (34,35).
3. An optical sensing system as claimed in claim 1, characterised in that the deflection means (11) is actuable to deflect the incident light beam (10) sequentially into first and then second optical sensor arrays (30,31) and the recirculated light beam sequentially into third and fourth optical sensor arrays (34,35).
4. An optical sensing system as claimed in any preceding claim, characterised in that the light recirculating means comprises at least one reflector (21,22,23,24) .
5. An optical sensing system as claimed in any preceding claim, characterised in that the deflection means (11) comprises an acousto-optic modulator.
6 . A method of operating an optical sensing system having two or more optical sensor arrays, characterised in the steps of selectively deflecting light, with a light deflection means, to a first sensor array, recirculating undeflected light to the light deflection means and deflecting the recirculated light to a second optical sensor array.
7. A method as claimed in claim 6, characterised in that the light is sequentially deflected to first and second optical sensor arrays and the recirculated light is sequentially deflected to third and fourth optical sensor arrays.
8. A method as claimed in claim 6, characterised in that the light is deflected substantially simultaneously to first and second optical sensor arrays and the recirculated light is deflected substantially simultaneously to third and fourth optical sensor arrays.
9. A method as claimed in claim 6, characterised in the steps of illuminating an acousto-optic modulator with a beam of light, applying a pair of radio frequency pulses to the modulator to form an acoustic wave such that the wave interacts with the beam, deflecting the beam to a first optical sensor array, and recirculating light which is not deflected to the modulator such that the light can interact with the wave and be deflected to a second optical sensor array.
10. A method as claimed in claim 7, characterised in the steps of illuminating the acousto-optic modulator with a beam of light, sequentially applying first and second pairs of radio frequency pulses to the modulator to form first and second respective acoustic waves in the modulator, such that the first wave interacts with the beam to deflect it to a first optical sensor array and the second wave interacts with the beam to deflect it to a second optical sensor array, and recirculating light which is not deflected back to the modulator such that it interacts with the waves, the first wave deflecting the recirculated light to a third optical sensor array and the second wave deflecting the recirculated light to a fourth optical sensor array.
11. A method as claimed in claim 8, characterised in the steps of illuminating an acousto-optic modulator with a beam of light, applying at least two pairs of radio frequency pulses substantially simultaneously to form an acoustic wave in the modulator such that the wave interacts with the beam to divide the beam and to deflect the resulting beams into first and second optical sensor arrays, and recirculating light which is not deflected to the modulator such that it interacts with the wave and is divided into beams which are deflected into third and fourth optical sensor arrays.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9022242A GB2248684A (en) | 1990-10-12 | 1990-10-12 | Optical sensing systems |
| GB9022242.3 | 1990-10-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1992007238A1 true WO1992007238A1 (en) | 1992-04-30 |
Family
ID=10683653
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/GB1991/001718 WO1992007238A1 (en) | 1990-10-12 | 1991-10-03 | Optical sensing systems |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU8636191A (en) |
| GB (1) | GB2248684A (en) |
| WO (1) | WO1992007238A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8208506B2 (en) | 2007-01-26 | 2012-06-26 | Electro Scientific Industries, Inc. | Methods and systems for generating pulse trains for material processing |
| US9029731B2 (en) | 2007-01-26 | 2015-05-12 | Electro Scientific Industries, Inc. | Methods and systems for laser processing continuously moving sheet material |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7521651B2 (en) | 2003-09-12 | 2009-04-21 | Orbotech Ltd | Multiple beam micro-machining system and method |
| CN105547453B (en) * | 2015-11-30 | 2018-09-18 | 威海北洋电气集团股份有限公司 | A kind of light channel structure of time division multiplexing Scale Fiber-Optic Hydrophone Array |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58217917A (en) * | 1982-06-14 | 1983-12-19 | Mitsubishi Rayon Co Ltd | Optical transmission switch |
| JPS58217918A (en) * | 1982-06-14 | 1983-12-19 | Mitsubishi Rayon Co Ltd | Optical demultiplexer |
| EP0299638A2 (en) * | 1987-07-16 | 1989-01-18 | Gec-Marconi Limited | Improvements relating to optical sensing systems |
-
1990
- 1990-10-12 GB GB9022242A patent/GB2248684A/en not_active Withdrawn
-
1991
- 1991-10-03 WO PCT/GB1991/001718 patent/WO1992007238A1/en active Application Filing
- 1991-10-03 AU AU86361/91A patent/AU8636191A/en not_active Abandoned
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58217917A (en) * | 1982-06-14 | 1983-12-19 | Mitsubishi Rayon Co Ltd | Optical transmission switch |
| JPS58217918A (en) * | 1982-06-14 | 1983-12-19 | Mitsubishi Rayon Co Ltd | Optical demultiplexer |
| EP0299638A2 (en) * | 1987-07-16 | 1989-01-18 | Gec-Marconi Limited | Improvements relating to optical sensing systems |
Non-Patent Citations (2)
| Title |
|---|
| PATENT ABSTRACTS OF JAPAN ;vol. 80, no. 72 (P-265)4 April 1984 ;& JP,A,58 217 918 ( MITSUBISHI RAYON KK ) 19 December 1983 see abstract * |
| PATENT ABSTRACTS OF JAPAN ;vol. 80, no. 72 (P-265)4 April 1984;& JP,A,58 217 917 ( MITSUBISHI RAYON KK ) 19 December 1983 see abstract * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8208506B2 (en) | 2007-01-26 | 2012-06-26 | Electro Scientific Industries, Inc. | Methods and systems for generating pulse trains for material processing |
| TWI469461B (en) * | 2007-01-26 | 2015-01-11 | Electro Scient Ind Inc | Methods and systems for generating pulse trains for material processing |
| US9029731B2 (en) | 2007-01-26 | 2015-05-12 | Electro Scientific Industries, Inc. | Methods and systems for laser processing continuously moving sheet material |
| US10118252B2 (en) | 2007-01-26 | 2018-11-06 | Electro Scientific Industries, Inc. | Methods and systems for laser processing continuously moving sheet material |
Also Published As
| Publication number | Publication date |
|---|---|
| AU8636191A (en) | 1992-05-20 |
| GB9022242D0 (en) | 1991-06-12 |
| GB2248684A (en) | 1992-04-15 |
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