Optical sensor arrangement including polarization-altering sensor

• US 5,038,029 A
• Filed: 08/24/1989
• Issued: 08/06/1991
• Est. Priority Date: 08/27/1988
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Martens, Gerhard, Kordts, Jurgen
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Allen, Stephone
• Application Number:
  US07/398,040
• Time in Patent Office: 712 Days
• Field of Search: 250/225, 250/227, 250/231 P, 250/231.10, 250/231.19, 250/227.17, 324/96, 324/262
• US Class Current: 250/225
• CPC Class Codes: G01D 5/344 using polarisation G01D5/35303 takes precedence

Abstract

The invention relates to an optical sensor arrangement having a light emitting arrangement (2), which feeds a first emission light beam into a first emission optical waveguide (3) and a second emission light beam into a second emission optical waveguide, having a polarizer (5), which is coupled with the two emission optical waveguides and generates from the first and second emission light beam a respective linearly polarized light beam, and having an optical sensor (1), which alters the state of polarization of a supplied polarized light beam as a function of a physical quantity acting on the sensor and which supplies a sensor light beam formed from a polarized light beam. Behind the optical sensor (1) there is disposed an analyzer (7), which separates each sensor light beam into two linearly polarized reception light beams, one of which is fed to a light receiving arrangement (12) via a first reception optical waveguide (9) and the other via a second reception optical waveguide (11). From the reception light beams, the light receiving arrangement forms electrical signals, from which an evaluation circuit ( 13) determines the physical quantity.

Claims

1. Optical sensor arrangement having a light emission arrangement (2) for the feeding-in of a first emission light beam into a first emission optical waveguide (3) and a second emission light beam into a second emission optical waveguide (14), having a polarizer (5), coupled with the two emission optical waveguides for the generation of a linearly polarized light beam from both the first and second emission light beams, and having an optical sensor (1) for the alteration of the state of polarization of a supplied polarized light beam as a function of a physical quantity acting on the sensor and for the supply of a sensor light beam formed from a polarized light beam, characterized in that behind the optical sensor (1) there is disposed an analyzer (7) for the separation of each sensor light beam into two linearly polarized reception light beams, a light receiving arrangement (12), for the formation of electrical signals from the reception light beams to determine the physical quantity by an evaluation circuit (13) and a first reception optical waveguide (9) and a second reception optical waveguide (11), for feeding the reception light beams to the light receiving arrangement.

2. Optical sensor arrangement according to claim 1, characterized in that polarizer (5) and analyzer (7) are constructed as polarization splitter cubes.

3. Optical sensor arrangement according to claim 1, characterized in that a retardation plate (6) with a retardation between 1/4 and 1/8th of a wavelength is disposed between polarizer (5) and analyzer (7).

4. Optical sensor arrangement according to claim 1, characterized in that the light emission arrangement (2) is disposed for the temporally alternating feeding-in of the first and second emission light beam into the first and second emission optical waveguide (3, 14) respectively.

5. Optical sensor arrangement according to claim 1, characterized in that the light emission arrangement (2) is disposed for the amplitude modulation of the intensity of the first emission light beam with a first modulation signal with a first frequency and of the intensity of the second emission light beam with a second modulation signal with a second frequency, and for the simultaneous feeding-in of both of them into the first and second emission optical waveguides (3, 14).

6. Optical sensor arrangement according to claim 1, characterized in that the evaluation circuit (13) is disposed for the determination of the measure for the physical quantity from the electrical signals for the intensity of the reception light beams by formation of the ratio of the products I₁₁.I₂₂ and I₂₁.I₁₂, I₁₁ being the intensity of the reception light beam irradiated into the first reception optical waveguide (9) and derived from the first emission light beam, I₂₂ being the intensity of the reception light beam irradiated into the second reception optical waveguide (11) and derived from the second emission light beam, I₂₁ being the intensity of the reception light beam irradiated into the second reception optical waveguide (11) and derived from the first emission light beam, and I₁₂ being the intensity of the reception light beam irradiated into the first reception optical waveguide (9) and derived from the second emission light beam.