Optical radiation wavelength determining equipment - has detectors having different spectral sensitivities and computer determining incident light wavelength

摘要

The optical radiation wavelength determining equipment includes at least two detectors with different spectral sensitivity and a computer for determining the incident light wavelength from the photo-current difference or ratio. The equipment may employ photodiodes (10,11) of different types (e.g. Si and InGaAs) or of the same type, a spectral damping filter (13) being positioned in front of one of the photodiodes when identical photodiodes are used. Alternatively, the detectors may be replaced by a quadrant diode with sectors of different spectral or absolute sensitivity, two quadrants reproducing the wavelength in the normal range and the other two quandrants giving wavelengths for irradiaiton intensities which control the first two quadrants. The second two quadrants are damped by neutral filters and the quadrant detector is associated with a high pass filter for suppressing background light. ADVANTAGE - Allows instantaneous wavelength determination.