Infrared optical sensor incorporating a transmission measuring cell
Disclosed is an infrared optical sensor for the continuous analysis of a liquid flowing in a pipe. The sensor includes, in a housing, a central section of duct through which the liquid to be analyzed flows, and a spectral analysis device using a light beam, including an infrared source which emits a signal which is received by a receiving device having passed through the liquid, an optical component which allows the light beam to pass through the liquid, and a support plate which carries the infrared source and the receiving device. The liquid to be analyzed circulates through a loop formed by walls in the form of an arch of the optical component and by a projection of the housing in the optical component. A sealing gasket is compressed between the optical component and the housing, in order to prevent any diffusion of liquid on the interior of the housing.
1. An optical sensor for the analysis of a liquid, the optical sensor ( 100 ) comprising:
a housing ( 1 );
a duct ( 2 ′) having a central section configured to permit the liquid to flow; and
a spectral analysis device, comprising an infrared source ( 22 ) that emits a light beam ( 30 ) in an infrared wavelength band, and a receiving device ( 28 ) that receives the light beam ( 30 ), the light beam arranged to pass through the liquid before being received by the receiving device, the spectral analysis device further comprising a base ( 16 ), an optical component ( 9 ) that analyzes the light beam, and a support plate ( 13 ), arranged on the base ( 16 ), which carries the infrared source ( 22 ) and the receiving device ( 28 ),
wherein the liquid is caused to flow through a loop ( 4 ) in the central section of the duct ( 2 ′) enclosed by walls of the optical component ( 9 ) that forms twin arches ( 50 , 52 ),
wherein the housing ( 1 ) forms a projection ( 60 ) in said twin arches,
wherein a sealing gasket ( 10 ) is compressed between the optical component ( 9 ) and the housing ( 1 ) such to prevent any diffusion of the liquid on an interior of the housing ( 1 ), and
wherein a first arch ( 52 ) of the twin arches is formed in a plane of propagation of the light beam ( 30 ), and a second arch ( 50 ) of the twin arches is formed in a plane perpendicular to said plane of propagation of the light beam ( 30 ).
2. The optical sensor for the analysis of a liquid as claimed in claim 1 , wherein the optical component ( 9 ) incorporates at least one combination comprised of a first ( 91 ) reflective wall and a second ( 92 ) reflective wall, said first and second reflective walls being inclined in relation to the optical beam ( 30 ) to form an outward/return optical path on the support plate ( 13 ) between the infrared source ( 22 ) and the receiving device ( 28 ).
3. The optical sensor for the analysis of a liquid as claimed in claim 2 , wherein the first reflective wall ( 91 ) and the second reflective wall ( 92 ) are configured as planar or aspherical concave surfaces.
4. The optical sensor for the analysis of a liquid as claimed in claim 3 , wherein the light beam ( 30 ) is divergent in a direction of the first reflective wall ( 91 ), said first reflective wall ( 91 ) configured as a concave wall, such that the light beam ( 30 ) passes through the liquid that flows in the loop ( 4 ) and is focused on the second reflective wall ( 92 ) before reaching the receiving device ( 28 ).
5. The optical sensor for the analysis of a liquid as claimed in claim 3 , wherein at least one of the first and second reflective walls is comprised of a reflector ( 24 , 26 ) secured to the optical component ( 9 ).
6. The optical sensor for the analysis of a liquid as claimed in claim 2 , wherein the light beam ( 30 ) is divergent in a direction of the first reflective wall ( 91 ), said first reflective wall ( 91 ) configured as a concave wall, such that the light beam ( 30 ) passes through the liquid that flows in the loop ( 4 ) and is focused on the second reflective wall ( 92 ) before reaching the receiving device ( 28 ).
7. The optical sensor for the analysis of a liquid as claimed in claim 6 , wherein at least one of the first and second reflective walls is comprised of a reflector ( 24 , 26 ) secured to the optical component ( 9 ).
8. The optical sensor for the analysis of a liquid as claimed in claim 2 , wherein at least one of the first and second reflective walls is comprised of a reflector ( 24 , 26 ) secured to the optical component ( 9 ).
9. The optical sensor for the analysis of a liquid as claimed in claim 1 , wherein the twin arches ( 50 , 52 ) and the projection ( 60 ) of the housing ( 1 ) form the loop ( 4 ) in the central section of duct ( 2 ′) at a core of the optical component ( 9 ) which accommodates the liquid.
10. The optical sensor for the analysis of a liquid as claimed in claim 1 , wherein the wavelength band is in the near-infrared spectrum.
11. The optical sensor for the analysis of a liquid as claimed in claim 1 , wherein the infrared source ( 22 ) is a light-emitting diode.
12. The optical sensor for the analysis of a liquid as claimed in claim 1 , wherein means of attachment ( 15 , 17 ) are provided for a secure fixing of the support plate ( 13 ) to the housing ( 1 ) that enables adjustable compression of the gasket ( 10 ).
13. A method for the analysis of a liquid, comprising:
providing an optical sensor ( 100 ), that comprises
a housing ( 1 ),
a duct ( 2 ′) having a central section configured to permit the liquid to flow, and
a spectral analysis device, comprising an infrared source ( 22 ) that emits a light beam ( 30 ) in an infrared wavelength band, and a receiving device ( 28 ) that receives the light beam ( 30 ), the light beam arranged to pass through the liquid before being received by the receiving device, the spectral analysis device further comprising a base ( 16 ), an optical component ( 9 ) that analyzes the light beam, and a support plate ( 13 ), arranged on the base ( 16 ), which carries the infrared source ( 22 ) and the receiving device ( 28 ),
wherein the liquid is caused to flow through a loop ( 4 ) in the central section of the duct ( 2 ′) enclosed by walls of the optical component ( 9 ) that forms twin arches ( 50 , 52 ),
wherein the housing ( 1 ) forms a projection ( 60 ) in said twin arches,
wherein a sealing gasket ( 10 ) is compressed between the optical component ( 9 ) and the housing ( 1 ) such to prevent any diffusion of the liquid on an interior of the housing ( 1 ), and
wherein a first arch ( 52 ) of the twin arches is formed in a plane of propagation of the light beam ( 30 ), and a second arch ( 50 ) of the twin arches is formed in a plane perpendicular to said plane of propagation of the light beam ( 30 );
circulating the liquid in the loop ( 4 ) of the central section of duct ( 2 ′) of the sensor;
turning on the infrared source ( 22 ) of the sensor to emit a divergent beam ( 30 ); and
orienting the light beam ( 30 ) in the optical component ( 9 ) towards a first reflective wall ( 91 ) of the optical component to render the light beam convergent, and then routing the beam via the loop ( 4 ), whereafter the light beam undergoes a second reflection on a second reflective wall ( 92 ) of the optical component, and finally is routed towards the receiving device ( 28 ) on the support plate ( 13 ).
14. The analysis method as claimed in claim 13 , wherein the light beam ( 30 ) is dispersed such that a full beam of the light beam does not reach the receiving device ( 28 ), and the base ( 16 ) is configured for at least partial reception of said dispersed beam, such that the reception by the base ( 16 ) of said dispersed beam supplements reception by the receiving device ( 28 ).