Laser diode gas sensor
First Claim
1. A laser diode gas sensor for the spectroscopic measurement of at least one component of a gas sample, comprising:
- a retroreflector, said retroreflector including a matrix having a plurality of triple mirrors forming a triple mirror matrix;
a concave mirror, said retroreflector cooperating with said concave mirror to define between them an optical measuring path with the gas sample to be analyzed;
a laser diode;
a detector; and
laser direction means for directing laser light from said laser diode onto the retroreflector, said laser direction means providing a weekly divergent bundle of laser beams, laser light reflected by the retroreflector being directed by said concave mirror to said detector, in order to determine an intensity of laser light after passing through the optical measuring path, and to determine an indicator for the concentration of the gas component to be analyzed on the basis of said intensity, said concave mirror being provided centrally with an opening transparent to laser light, through which opening said weakly divergent bundle of laser beams is directed onto said retroreflector, so that said triple mirror matrix is illuminated essentially over its entire surface; and
said concave mirror is arranged or shaped such that the bundle of laser beams reflected by said retroreflector is focused by said concave mirror directly on said detector, said detector being arranged outside a principal beam path of a bundle of laser beams reflected from said retroreflector.
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Accused Products
Abstract
A laser diode gas sensor for the spectroscopic measurement of a gas sample, with a retroreflector and a concave mirror, which define between them an open measuring path with the gas to be analyzed. Laser light passes through the measuring path, is reflected at the retroreflector, and is directed toward a detector via a concave mirror in order to determine the mean concentration of the gas component to be analyzed in the optical measuring path. Optical elements, such as beam splitters, lenses, etc., which lead to losses of intensity, were used before to couple the laser light into the beam path onto the retroreflector, and to decouple the reflected light to the detector. An improved optical imaging array, which minimizes losses, is provided. The concave mirror is provided centrally with an opening transparent to the laser light, through which a weakly divergent bundle of laser light is directed onto the retroreflector, so that the retroreflector is illuminated essentially over its entire surface. The retroreflector is made with a matrix consisting of a plurality of triple mirrors, which reflect the incident, weakly divergent bundle of laser beams as a bundle of laser beams with convergent properties onto the concave mirror. The concave mirror is arranged or shaped such that the laser light reflected by the retroreflector is focused by the concave mirror directly onto the detector, which is arranged outside the principal beam path.
80 Citations
20 Claims
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1. A laser diode gas sensor for the spectroscopic measurement of at least one component of a gas sample, comprising:
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a retroreflector, said retroreflector including a matrix having a plurality of triple mirrors forming a triple mirror matrix; a concave mirror, said retroreflector cooperating with said concave mirror to define between them an optical measuring path with the gas sample to be analyzed; a laser diode; a detector; and laser direction means for directing laser light from said laser diode onto the retroreflector, said laser direction means providing a weekly divergent bundle of laser beams, laser light reflected by the retroreflector being directed by said concave mirror to said detector, in order to determine an intensity of laser light after passing through the optical measuring path, and to determine an indicator for the concentration of the gas component to be analyzed on the basis of said intensity, said concave mirror being provided centrally with an opening transparent to laser light, through which opening said weakly divergent bundle of laser beams is directed onto said retroreflector, so that said triple mirror matrix is illuminated essentially over its entire surface; and
said concave mirror is arranged or shaped such that the bundle of laser beams reflected by said retroreflector is focused by said concave mirror directly on said detector, said detector being arranged outside a principal beam path of a bundle of laser beams reflected from said retroreflector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A laser diode gas sensor for the spectroscopic measurement of at least one component of a gas sample, comprising:
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a retroreflector, said retroreflector including a matrix having a plurality of triple mirrors forming a triple mirror matrix; a concave mirror with a central opening transparent to laser light, said retroreflector cooperating with said concave mirror to define between them an optical measuring path with the gas sample to be analyzed; a laser diode; a detector; laser direction means for directing laser light from said laser diode onto the retroreflector including a first optical fiber line extending from said laser diode and a collimator arranged at an end of said optical fiber line adjacent to said central opening of said concave mirror, said laser direction means providing a weekly divergent bundle of laser beams, laser light reflected by the retroreflector being directed by said concave mirror to said detector, in order to determine an intensity of laser light after passing through the optical measuring path, and to determine an indicator for the concentration of the gas component to be analyzed on the basis of said intensity, said weakly divergent bundle of laser beams being directed through said central opening onto said retroreflector, so that said triple mirror matrix is illuminated essentially over its entire surface and said concave mirror being arranged or shaped such that the bundle of laser beams reflected by said retroreflector is focused by said concave mirror directly on said detector, said detector being arranged outside a principal beam path of a bundle of laser beams reflected from said retroreflector. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A laser diode gas sensor for the spectroscopic measurement of at least one component of a gas sample, comprising:
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a retroreflector, said retroreflector including a matrix having a plurality of triple mirrors forming a triple mirror matrix; a concave mirror, said retroreflector cooperating with said concave mirror to define between them an optical measuring path with the gas sample to be analyzed; a laser diode; a detector, said laser diode directing laser light onto the retroreflector, laser light reflected by the retroreflector being directed by said concave mirror to said detector, in order to determine an intensity of laser light after passing through the optical measuring path, and to determine an indicator for the concentration of the gas component to be analyzed on the basis of said intensity, said concave mirror being provided centrally with an opening transparent to laser light, through which opening a weakly divergent bundle of laser beams is directed onto said retroreflector, so that said triple mirror matrix is illuminated essentially over its entire surface; and
said concave mirror is arranged or shaped such that the bundle of laser beams reflected by said retroreflector is focused by said concave mirror directly on said detector, said detector being arranged outside a principal beam path of a bundle of laser beams reflected from said retroreflector;conversion means for converting a phase-sensitive amplified 1f signal generated by amplitude modulation of the laser light into an acoustic signal by voltage-frequency conversion; and a control and evaluation unit, said conversion means being provided in said control and evaluation unit, so that a user can optimize the adjustment of the gas sensor on the basis of the pitch of the acoustic signal.
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Specification