| 摘要 |
OPTICAL SENSOR An optical sensor comprises a polychromatic light source (3), a detector (4), and first and second polarisers (7) (8) disposed in the light path between the source and the detector. The polarisation axis of the first polariser (7) is substantially orthogonal to that of the second (8), and there is a modulating element (6) of birefringent material disposed therebetween. The modulating element is disposed such that a change in the parameter to be measured alters the optical path length of the polychromatic light through the modulating element, thereby changing the colour of the light incident on the detector (4). The detector comprises first and second photo-responsive elements (9) (10), the responsivity with respect to wavelength of the first element (9) being different from that of the second (10). Signals from the photo-responsive elements are fed to a microprocessor (13) which calculates the colour of the light incident on the detector as represented by two or more paramters on the Chromaticity (CIE) Diagram, and interprets this colour in terms of the parameter to be measured. |
