GB2292479A - Spectroscopic system using surface emission laser - Google Patents

Spectroscopic system using surface emission laser Download PDF

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Publication number
GB2292479A
GB2292479A GB9516803A GB9516803A GB2292479A GB 2292479 A GB2292479 A GB 2292479A GB 9516803 A GB9516803 A GB 9516803A GB 9516803 A GB9516803 A GB 9516803A GB 2292479 A GB2292479 A GB 2292479A
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GB
United Kingdom
Prior art keywords
radiation source
laser diode
radiation
substrate
source according
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Withdrawn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
GB9516803A
Other versions
GB9516803D0 (en
Inventor
Regina Best-Timmann
Peter Dreyer
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.)
Draegerwerk AG and Co KGaA
Original Assignee
Draegerwerk AG and Co KGaA
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 Draegerwerk AG and Co KGaA filed Critical Draegerwerk AG and Co KGaA
Publication of GB9516803D0 publication Critical patent/GB9516803D0/en
Publication of GB2292479A publication Critical patent/GB2292479A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48091—Arched
    • 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
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/022—Mountings; Housings
    • H01S5/0225—Out-coupling of light
    • H01S5/02257—Out-coupling of light using windows, e.g. specially adapted for back-reflecting light to a detector inside the housing
    • 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
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/024—Arrangements for thermal management
    • H01S5/02407—Active cooling, e.g. the laser temperature is controlled by a thermo-electric cooler or water cooling
    • H01S5/02415—Active cooling, e.g. the laser temperature is controlled by a thermo-electric cooler or water cooling by using a thermo-electric cooler [TEC], e.g. Peltier element
    • 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
    • H01S5/00—Semiconductor lasers
    • H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/068—Stabilisation of laser output parameters
    • H01S5/06804—Stabilisation of laser output parameters by monitoring an external parameter, e.g. temperature
    • 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
    • H01S5/00—Semiconductor lasers
    • H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/068—Stabilisation of laser output parameters
    • H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
    • 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
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/18—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
    • H01S5/183—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Analytical Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Optics & Photonics (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Description

Radiation source for a measurinq svstem 2292479 This invention relates to
a radiation source for a measuring system for the spectroscopic analysis of the proportion of a material in a gas sample.
A device for the spectroscopic analysis of the proportion of a material in a gas sample is known from DE-A-4122572. Oxygen concentrations are measured with the known device by means of radiation absorption in the wave length range of about 760 nanometers. As a radiation source, a so-called edge-emitting laser diode having a monitor diode is used, with a wave length range of 759 to 764 nanometers. The radiation which emerges from the front of the laser diode is used as measuring radiation, whereas the radiation which emerges from the back of the laser diode passes to the monitor diode. The laser diode is fed by a control current which consists of a continuous- current portion and an alternating-current portion having a frequency of 5 KHz. The operating current of the laser diode is adjusted to the continuous-current portion of the control current, while the alternating-current portion effects a periodic detuning in the region of the absorption lines. In order to achieve a driving of the laser diode that is as harmonic-free as possible, a sinusoidal curve shape is chosen for the alternating current. The laser diode and the monitor diode are mounted as a block on a tempering device so that the temperature-operating point of the laser diode can be adjusted and so that, as a result, the laser diode can be brought onto one of the known absorption lines of oxygen. Because the absorption lines are weak, in particular in the case of oxygen, the second derivative of the absorption line, is used for the concentration measurement. Within the absorption line, the operating point generally lies on the middle extremum of the second derivative of the absorption line. After the radiation which is emitted by the laser diode has passed through the gas which is to be examined, it makes contact with a detector device which is connected to an evaluating circuit. The evaluating circuit substantially consists of a lock-in intensifier, to the signal input which is admitted the measuring signal of the detector device and to the reference input of which is admitted a signal voltage of double the frequency of the drive of the laser diode. The output signal of the lock-in intensifier corresponds to the second derivative of the absorption signal.
In the case of the known device, it is disadvantageous that an alteration of the temperature of the tempering device causes an alteration of the operating current, and that ageing of the edge-emitting laser diode can cause it to change longitudinal mode whereby a sudden frequency jumping or mode jumping occurs. It is further disadvantageous that the radiation which emerges from the back of the laser diode (rather than the measuring radiation which passes through the gas which is to be examined) is admitted to the monitor diode. As a result of this, inaccuracies in the measurement of the radiation capacity of the laser diode by means of the monitor diode may occur.
A measuring system for the spectroscopic analysis of the proportion of oxygen in a gas sample, the system having a Peltier element as a tempering device, is known from US-A-4730112. The Peltier element is sandwiched between two metallic carrier plates one of which forms the warm side and the other of which forms the cold side of the Peltier element. An edge-emitting laser diode is used as a radiation source, which laser diode is attached to the "cold" carrier plate of the Peltier element via a cooling plate. The radiation from the back of the laser diode is registered by a monitor diode located on the "cold" carrier plate, while the measuring radiation which emerges from the laser diode is routed by way of a light guide to the gas sample which is to be analysed.
In the case of this known measuring system, the complicated construction of the radiation transmitter with the cooling plate is disadvantageous.
A display system for the projection of data into the field of vision of a person wearing a helmet is known from US-A-5325386. An essential component of the display system is an array of vertically-emitting laser diodes, which are arranged on a substrate as a carrier and are controlled by way of an electronic circuit. With the array of laser diodes, both colour and monochromatic reproductions can be realised with high resolution.
The object of the present invention is to improve a radiation source for a measuring system for the spectroscopic analysis of the proportion of a material in a gas sample in such a way that the occurrence of mode jumping is reduced.
According to the present invention, there is provided a radiation source for a measuring system for the spectroscopic analysis of the proportion of a material in a gas sample, having at least one tempering device for adjusting the temperature-operating point of the radiation source, wherein the radiation source is a laser diode which is located on a planar substrate and is able to emit in a vertical or substantially vertical manner with respect to the substrate.
The invention is based on the finding that vertically-emitting laser diodes can be used in a particularly advantageous manner in IRspectroscopy because of their small angle of radiation and their good capacity for tuning in the wave length range which is used for the gas analysis. In comparison with edgeemitting laser diodes, vertically-emitting laser diodes have the advantage that, as a result of their small resonator, they have large distances between the individual modes, so that within one mode, the diode can be turned to a wave length range of approximately one nanometer.
The laser diode is advantageously constructed as an array e.g. a chiplike array of individual vertically-emitting laser diodes which are tuned to different wave lengths, in order that the absorptions of the measuring radiation in the case of different wave lengths can be measured.
A particularly simple and compact construction in connection with a tempering device having a Peltier element results if the substrate which supports the laser diode is secured surficially to a carrier plate of the Peltier element, in which case the cold side of the Peltier element is normally used as a carrier plate. Apart from the Peltier element, the tempering device may comprise also a control apparatus which is used as the energy supply of the Peltier element.
There is advantageously provided on the carrier plate which accommodates the substrate, a temperature probe which is connected to the tempering device. The temperature probe measures the temperature in the surroundings of the laser diode and can be attached either to the substrate or directly to the carrier plate. Inside the control apparatus of the tempering device, the temperature which is measured with the temperature probe is compared with a desired value of a temperature-operating point, and the supply voltage of the Peltier element is then altered until the predetermined temperature and the measured temperature coincide.
There is advantageously provided, in the emission region of the laser diode, a disc or reflector which at least partially reflects the emitted radiation and is permeable to transmission radiation. Secured to the carrier plate which accommodates the laser diode, or to the substrate, there is a monitor diode which is located in the path of at least part of the radiation which is reflected by the disc or reflector. Because a part of the emitted radiation is measured by the monitor diode, a particularly good control of the radiation capacity of the laser diode is possible in this way. In the case of edge-emitting diodes, known from IR-spectroscopy, the radiation from the rear of the laser is normally used to control the capacity, which in general does not have the same radiation intensity as the measuring radiation, which is radiated through the gas sample.
In an advantageous construction of the radiation source according to the invention, the Peltier element is secured in the region of the base of a pot-like housing which is provided with contact pins, and the side of the housing that is opposite the base is closed off by the disc or reflector.
An exemplary embodiment of the invention is represented in the drawing and explained in greater detail in the following.
The single Figure shows in a diagrammatic manner a radiation source 1 according to the invention in longitudinal section. The radiation source 1 consists of a laser diode 2 on a flat substrate 8, which laser diode 2 emits a measuring ray 12 in a vertical manner with respect to the substrate 8 and is fixed surficially to a first carrier plate 3 of a Peltier element 4. The first carrier plate 3 corresponds to the cold side of the Peltier element 4. A second carrier plate 5, which is arranged in a sandwich-like manner in respect of the first carrier plate 3 and which forms the warm side of the Peltier element 4, is secured to the base 6 of a pot-like housing 7.
Further attached to the substrate 8 are a monitor diode 9 and a temperature probe 10. The temperature probe 10, the Peltier element 4 and a control apparatus 15 having a desired-value regulator 16 for a temperature T, together form a tempering device 17 for adjusting the temperature-operating-point T of the laser diode 2.
Contact between the Peltier element 4, the laser diode 2, the monitor diode 9 and the temperature probe 10 is effected by means of contact pins 11 on the base 6 of the housing 7. The right hand contact pin 11 is connected to the temperature probe 10; the two contact pins 11 to the left of the right hand contact pin contact the Peltier element 4.
The control apparatus 15 substantially consists of a voltage supply unit (not shown) for the Peltier element 4 and of a controller (likewise not shown), to which is admitted the measuring value of the temperature probe 10 as an actual value, and a specified variable for the temperature-operating point T, which specified variable is adjusted in the desiredvalue regulator 16.
The housing 7 is closed off on the side which is opposite the base 6 by a disc 13 on which portions 14 of the measuring ray 12 emitted by the laser diode 2 are reflected in the direction of the monitor diode 9.
The ray 12 is represented only in a diagrammatic manner, because the radiation emission of the laser diode 2 takes place over a certain angle of radiation.
The measuring system for the spectroscopic analysis of the proportion of a material to be detected in a gas sample can be, for example, constructed according to DE-A-41 22 572.

Claims (7)

Claims
1. A radiation source for a measuring system for the spectroscopic analysis of the proportion of a material in a gas sample, having at least one tempering device for adjusting the temperature-operating point of the radiation source, wherein the radiation source is a laser diode which is located on a planar substrate and is able to emit in a vertical or substantially vertical manner with respect to the substrate.
2. A radiation source according to claim 1, wherein the laser diode comprises an array, e.g. a chip-like array, of individual vertically-emitting laser diodes, the emission rays of which can be adjusted to different wave lengths.
is
3. A radiation source according to claim 1 or 2, wherein the substrate, together with the laser diode, are secured such that the substrate rests surficially on a first carrier plate of a Peltier element, which is part of the tempering device.
4. A radiation source according to claim 3, wherein, in the region of the substrate, or of the first carrier plate which accommodates the substrate, there is provided a temperature probe which is connected to the tempering device.
S. A radiation source according to any of claims 1 to 4, wherein, in the emission region of the laser diode, there is provided a disc or reflector which is able at least partially to reflect the emitted _radiation and is permeable to transmission radiation, and wherein there is provided a monitor diode which is aligned with at least part of the rays which in use are reflected by the disc or reflector.
6. A radiation source according to any of claims 3 to 5, wherein the side of the Peltier element that is opposite the first carrier plate is secured to the base of a pot-like housing which is provided with contact pins and is closed off by the disc or reflector.
7. A radiation source according to claim 1, substantially as hereinbefore described with reference to, and as shown in, the drawing.
GB9516803A 1994-08-19 1995-08-16 Spectroscopic system using surface emission laser Withdrawn GB2292479A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE4429582A DE4429582C2 (en) 1994-08-19 1994-08-19 Radiation source for a measuring system

Publications (2)

Publication Number Publication Date
GB9516803D0 GB9516803D0 (en) 1995-10-18
GB2292479A true GB2292479A (en) 1996-02-21

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GB9516803A Withdrawn GB2292479A (en) 1994-08-19 1995-08-16 Spectroscopic system using surface emission laser

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GB (1) GB2292479A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2373096A (en) * 2001-03-08 2002-09-11 Siemens Plc A Wavelength Stabilised Laser Source
WO2009024134A1 (en) * 2007-08-20 2009-02-26 Schmidt & Haensch Gmbh & Co. Method and device for the exact and controlled effective wavelength adjustment of the emitted radiation of a light-emitting diode
DE102009033979A1 (en) 2009-07-16 2011-01-20 Schmidt & Haensch Gmbh & Co. Device for focusing wavelength adjustment of emitted optical radiation

Families Citing this family (9)

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Publication number Priority date Publication date Assignee Title
JPH1051067A (en) * 1996-04-29 1998-02-20 Motorola Inc Reflection type power monitoring system for vertical cavity surface emission laser
DE19717145C2 (en) * 1997-04-23 1999-06-02 Siemens Ag Method for the selective detection of gases and gas sensor for its implementation
GB2327297A (en) * 1997-07-14 1999-01-20 Mitel Semiconductor Ab Lens cap
JP3343680B2 (en) * 1999-07-12 2002-11-11 日本酸素株式会社 Laser spectrometer
DE10063678A1 (en) * 2000-12-20 2002-07-18 Siemens Ag Method for the selective detection of gases using laser spectroscopy
WO2002073757A2 (en) * 2001-03-08 2002-09-19 Siemens Plc A wavelength stablilised laser source
US6868104B2 (en) * 2001-09-06 2005-03-15 Finisar Corporation Compact laser package with integrated temperature control
JP2008513736A (en) * 2004-09-14 2008-05-01 フラウンホーファー・ゲゼルシャフト ツア フェルデルンク デア アンゲヴァンテン フォルシュンク エー．ファウ． Equipment for measuring one or more types of gas components
US11764542B2 (en) * 2017-12-15 2023-09-19 Horiba, Ltd. Semiconductor laser device, and method and program for driving the same

Citations (2)

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Publication number Priority date Publication date Assignee Title
US4730112A (en) * 1986-03-07 1988-03-08 Hibshman Corporation Oxygen measurement using visible radiation
US5311526A (en) * 1993-02-25 1994-05-10 At&T Bell Laboratories Article that comprises a semiconductor laser, and method of operating the article

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JPS55148482A (en) * 1979-05-08 1980-11-19 Canon Inc Semiconductor laser device
DE3633931A1 (en) * 1986-10-04 1988-04-07 Kernforschungsz Karlsruhe METHOD AND DEVICE FOR CONTINUOUSLY MEASURING THE CONCENTRATION OF A GAS COMPONENT
DE8915890U1 (en) * 1989-10-26 1992-01-16 Daimler-Benz Aerospace Aktiengesellschaft, 80995 München Monolithically integrated Peltier cooling element
DE4110095C2 (en) * 1991-03-27 1998-02-12 Draegerwerk Ag Method for gas spectroscopic measurement of the concentration of a gas component
DE4122572A1 (en) * 1991-07-08 1993-01-14 Draegerwerk Ag METHOD FOR OPERATING A LASER DIODE
US5325386A (en) * 1992-04-21 1994-06-28 Bandgap Technology Corporation Vertical-cavity surface emitting laser assay display system
DE4216508A1 (en) * 1992-05-19 1993-11-25 Ortwin Dr Brandt IR analysis of solids via selective gasification - allows measurements of discrete rotational and vibrational spectral lines e.g. determn. of carbon sulphur in sample of iron as carbon- and sulphur di:oxide(s)
DE4235768A1 (en) * 1992-10-24 1994-05-19 Cho Ok Kyung Modified semiconductor laser diode with integrated temperature control part

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US4730112A (en) * 1986-03-07 1988-03-08 Hibshman Corporation Oxygen measurement using visible radiation
US5311526A (en) * 1993-02-25 1994-05-10 At&T Bell Laboratories Article that comprises a semiconductor laser, and method of operating the article

Non-Patent Citations (3)

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Title
Electronics Letters, vol 30, no 17, 18.8.94, Y Kohama et al,"0.85 micron bottom emitting cont..../ *
Electronics letters, vol 30, no 18, 1.9.94, Y Ohiso et al, "Thermal interference", pgs 1491-1492 *
vertical cavity surface emitting lasers" pages 1406-7 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2373096A (en) * 2001-03-08 2002-09-11 Siemens Plc A Wavelength Stabilised Laser Source
GB2373096B (en) * 2001-03-08 2005-08-03 Siemens Plc A wavelength stabilised laser source
WO2009024134A1 (en) * 2007-08-20 2009-02-26 Schmidt & Haensch Gmbh & Co. Method and device for the exact and controlled effective wavelength adjustment of the emitted radiation of a light-emitting diode
DE102009033979A1 (en) 2009-07-16 2011-01-20 Schmidt & Haensch Gmbh & Co. Device for focusing wavelength adjustment of emitted optical radiation
EP2296073A1 (en) 2009-07-16 2011-03-16 Schmidt & Haensch GmbH & Co. Device for shear point wavelength adjustment of emitted optical radiation

Also Published As

Publication number Publication date
DE4429582C2 (en) 1998-02-26
DE4429582A1 (en) 1996-02-22
GB9516803D0 (en) 1995-10-18

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