Apparatus for sensing the wavelength and intensity of light

An optoelectric detection system comprising:

• a photoelectric semiconductor device including;
• a semiconductor substrate;
• at least two PN junctions formed in said semiconductor substrate at different depths from the surface of said semiconductor substrate;
• first output electrode means for developing first output signals derived from the deeper of said at least two PN junctions;
• and
• second output electrode means for developing second output signals derived from the shallower of said at least two PN junctions;
• a first logarithmic compression circuit for logarithmically compressing said first output signals;
• a second logarithmic compression circuit for logarithmically compressing said second output signals;
• a subtractor connected to receive output signals derived from said first logarithmic compression circuit and said second logarithmic compression circuit, respectively, and
• an adder connected to receive outputs from said first and second logarithmic compression circuits;
• said subtractor developing a third output signal related to the wavelength of light impinging on said photoelectric semiconductor device;
• said adder developing a fourth output signal related to the intensity of light impinging on said photoelectric semiconductor device;
• said first PN junction being sensitive to light of a first particular wavelength band;
• said second PN junction being sensitive to light of a second predetermined wavelength band including wavelengths greater than those in said first particular wavelength band;
• said first PN junction and said second PN junction have substantially equivalent sensitivities to light intensity.