Abstract
An optical gas sensor (1), for quantitatively measuring a concentration of one or more gases, includes a radiation source (2) for emitting light waves (L), a cuvette (3) for holding a gas (G) to be measured, and a detector (4) for measuring light intensities. The light source (2) includes at least one emitter (5) of light waves (L) and is configured to emit light waves (L) of at least one first wavelength and of a second wavelength different from the first wavelength simultaneously or separately from each other. The emitter (5) is further configured to emit a spectrum the full half-life width of which is a maximum 50% of the effective wavelength, and to emit light waves (L) having a controlled beam path. The detector (4) is configured to quantitatively detect an intensity of emitted light waves (L) of the first wavelength and of the second wavelength.
Claims
1. An optical gas sensor for quantitatively measuring the concentration of one or more gases, the optical gas sensor comprising: a radiation source for emitting light waves; a cuvette for holding a gas to be measured; and a detector for measuring light intensities, wherein: the radiation source comprises at least one emitter of light waves and is configured to emit light waves of at least one first wavelength and of a second wavelength different from the first wavelength simultaneously as well as separately from one another; the emitter is configured to emit a spectrum, the full width at half maximum of which is a maximum 50% of the effective wavelength; and the detector being configured to quantitatively detect an intensity of the emitted light waves of the first wavelength and of the second wavelength.
2. An optical gas sensor in accordance with claim 1, wherein the radiation source comprises at least one first emitter and one second emitter, the first emitter is configured to emit light waves of the first wavelength and the second emitter is configured to emit light waves of the second wavelength, and the detector and/or at least one emitter comprising at least one optical filter.
3. An optical gas sensor in accordance with claim 1, wherein the radiation source is configured to emit a discrete spectrum of light waves, the full width at half maximum of which is a maximum 20% of the effective wavelength.
4. An optical gas sensor in accordance with claim 1, wherein the cuvette comprises a mirror arrangement with a plane mirror and a concave mirror arranged opposite the plane mirror, wherein an optical axis of the concave mirror is arranged essentially at right angles to the plane mirror.
5. An optical gas sensor in accordance with claim 4, wherein the radiation source and/or the detector are arranged at the plane mirror.
6. An optical gas sensor in accordance with claim 4, wherein the radiation source and the detector are arranged at the cuvette such that light waves emitted by the radiation source reach the detector directly.
7. An optical gas sensor in accordance with claim 1, wherein the radiation source is arranged at the cuvette spaced apart from the detector, the emitter being configured to emit light waves with a controlled beam path.
8. An optical gas sensor in accordance with claim 1, wherein the detector is precisely one detector that is arranged at the cuvette.
9. An optical gas sensor in accordance with claim 1, wherein at least two radiation sources are arranged at the cuvette spaced apart from one another.
10. An optical gas sensor in accordance with claim 9, further comprising another detector to provide two detectors, wherein the cuvette comprises at least the two detectors, the two detectors being configured to measure light intensities of different radiation sources or of different emitters of the two radiation sources.
11. An optical gas sensor in accordance with claim 5, wherein the radiation source and the detector are arranged at the cuvette such that light waves emitted by the radiation source reach the detector directly.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] In the drawings:
[0029] FIG. 1 is a schematic lateral sectional view of a first embodiment of a gas sensor according to the present invention;
[0030] FIG. 2 is a schematic top view of a plane mirror of the gas sensor according to the present invention from FIG. 1;
[0031] FIG. 3 is a schematic top view of a plane mirror of a second embodiment of a gas sensor according to the present invention; and
[0032] FIG. 4 is a schematic top view of a plane mirror of a third embodiment of a gas sensor according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] Referring to the drawings, the first embodiment of the optical gas sensor 1 according to the present invention shown in FIG. 1 comprises a cuvette 3 having an essentially cylindrical configuration, in which a gas G or a gas mixture to be measured is contained. The cuvette 3 comprises at least one opening, which cannot be seen in this view, for replacing the gas G contained in the cuvette with gas G from the surrounding area of the gas sensor 1. A plane mirror 6 is arranged at one end face of the cuvette 3 and a concave mirror 7 is arranged at another end face. The plane mirror comprises a radiation source 2, which is configured for emitting light waves L of two different wavelengths within the IR spectrum and is oriented in the direction of the concave mirror 7. The radiation source 2 comprises an emitter 5 that is configured as an LED and is configured such that light waves L of different wavelengths can be emitted separately from one another. An optical filter, e.g., a bandpass filter, dual bandpass filter or triple bandpass filter is optionally arranged in front of the emitter 5. A detector 4 is arranged at the plane mirror 6 spaced apart from the light source (radiation source) 2 and oriented in the direction of the concave mirror 7. The detector 4 is configured for measuring the intensity of the light waves. The concave mirror 7 comprises an optical axis 8, which is arranged essentially at right angles to the plane mirror 6. The distance of the concave mirror 7 to the emitter 5 is approximately half of the radius of curvature of the concave mirror 7 in this first embodiment. When using an optical filter arranged in front of the emitter 5, the distance is somewhat greater than half the radius of curvature of the concave mirror 7. Two different light beams L emitted by the radiation source 2 are shown in this view, wherein a first light beam L is schematically shown by a solid line and a second light beam L is schematically shown by a dotted line. The emitted light beams L are each reflected by the concave mirror 7 to the plane mirror 6 and again to the concave mirror 7 until they reach the detector 4. This arrangement is especially advantageous when the gas G to be measured absorbs light waves L only weakly and when the gas sensor 1 has to have an as compact as possible size.
[0034] FIG. 2 shows the plane mirror 6 of the first embodiment of the gas sensor 1 in a top view. The plane mirror 6 comprises a first aperture 9, in which a radiation source 2 with a first emitter 5a as well as with a second emitter 5b is arranged, and a second aperture 10, in which the detector 4 is arranged. This first embodiment of the gas sensor 1 according to the present invention is especially suitable for quantitatively measuring the concentration of a gas or for detecting an individual gas G. For this, light waves L of different wavelengths can be alternately emitted and/or be modulated with different frequencies by the first emitter 5a and by the second emitter 5b. The detector 4 determines the intensity of these partially absorbed light waves L. In this case, the light waves emitted by the second emitter 5b can be used as a reference signal. The first emitter 5a and the second emitter 5b are configured as LEDs in this embodiment.
[0035] FIG. 3 shows a plane mirror 6 of a second embodiment of the gas sensor according to the present invention in a top view. The plane mirror 6 comprises a first aperture 9, in which a radiation source 2 with a first emitter 5a, with a second emitter 5b as well as with a third emitter 5c is arranged, and a second aperture 10, in which the detector 4 is arranged. An optical filter, e.g., a bandpass filter, dual bandpass filter or triple bandpass filter is optionally arranged in front of the first emitter 5a and/or the second emitter 5b and/or the third emitter 5c. The first emitter 5a, the second emitter 5b and the third emitter 5c are configured as LEDs in this embodiment. The second embodiment of the gas sensor 1 differs from the first embodiment by the radiation source additionally comprising a third emitter 5c. This second embodiment of the gas sensor 1 according to the present invention is especially suitable for quantitatively measuring or for detecting two different gases G. For this, light waves L of different wavelengths can be emitted by the first emitter 5a, the second emitter 5b and the third emitter 5c. The detector 4 determines the intensity of these partially absorbed light waves L. In this case, e.g., the light waves emitted by the third emitter 5c are used as a reference signal.
[0036] FIG. 4 shows a plane mirror 6 of a third embodiment of the gas sensor 1 according to the present invention in a top view. The plane mirror 6 comprises two first apertures 9 and two second apertures 10. A first radiation source 2a with a first emitter 5a as well as with a second emitter 5b is arranged in a first aperture 9. A second radiation source 2b with a third emitter 5c as well as with a fourth emitter 5d is arranged in the other first aperture 9. A first detector 4a is arranged in a second aperture 10 and a second detector 4b is arranged in the other second aperture 10. The third embodiment of the gas sensor 1 differs from the first embodiment by the gas sensor 1 comprising two radiation sources 2 as well as two detectors 4. Light waves emitted by the first radiation source 2a can be detected preferably exclusively or essentially by the first detector 4a and light waves emitted by the second radiation source 2b can be detected exclusively or essentially by the second detector 4b. During operation the first radiation source 2a and the second radiation source 2b can simultaneously emit light waves L. The first emitter 5a, the second emitter 5b, the third emitter 5c and the fourth emitter 5d are configured as LEDs in this embodiment. This third embodiment of the gas sensor 1 according to the present invention is especially suitable for simultaneously quantitatively measuring and detecting two different gases G in a gas mixture. Bandpass filters, which are arranged in front of the radiation sources 2 or detectors 4, act as mirrors for light waves of each of the other radiation sources 2. This increases the efficiency of the gas sensor 1.
[0037] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
