Optoelectronic displacement sensor with correction filter

An optoelectronic displacement sensor for the absolute measurement of displacement in the submicrometer range, in particular for the positioning of optical waveguides, comprising:

• at least two light sources having a certain intensity distribution, said light sources being disposed one behind the other in a displacement direction;
• a pair of flat, thermally coupled, optoelectronic radiation sensors disposed opposite said light sources one behind the other in said displacement direction so that each of said light sources illuminates a corresponding of said radiation sensors and each of said radiation sensors delivers an output signal in dependence of said illumination;
• an electronic measuring circuit connected to said radiation sensors and forming the difference of said output signals of said two radiation sensors;
• a diaphragm disposed between said light sources and said radiation sensors, said diaphragm being displaceable in said displacement direction and being operable so that, in the case of a displacement of said diaphragm in one direction, the illuminated area of one of said radiation sensors is increased, while the illuminated area of the other of said radiation sensors is correspondingly reduced;
• and
• a correction filter having a transmissive filter area for each of said light sources, said correction filter being fixedly disposed between the respective of said light sources and said radiation sensors, and the transmission of said correction filter varying over said filter area so that inhomogenities in said intensity distribution of said light sources are specifically eliminated.

An optoelectronic displacement sensor for the absolute measurement of displacement in the submicrometer range, in particular for the positioning of optical waveguides, comprising:

• a light source having a certain intensity distribution;
• a monolithically integrated double photodiode with two photodiodes disposed opposite said light source beside one another, each of said photo diodes being illuminated at least partially by said light source and delivering an output signal in dependence of said illumination, one of said photodiodes thereby acting as a reference photodiode, and the other of said photodiodes acting as a measuring photodiode;
• an electronic measuring circuit connected to said photodiodes, comprising a regulating circuit to which said output signal of said reference photodiode is fed, and which supplies a regulated current through said light source;
• a diaphragm disposed between said light source and said photodiodes, said diaphragm being displaceable parallel to said photodiodes and being designed so that, in the case of a displacement of said diaphragm in one direction, only the illuminated area of said measuring photodiode is varied;
• and
• a correction filter having a transmissive filter area, said correction filter being fixedly disposed between said light source and said measuring photodiode, and the transmission of said correctiion filter varying over said filter area so that inhomogenities in said intensity distribution of said light source are specifically eliminated.

An optoelectronic displacement sensor for the absolute measurement of displacement in the submicrometer range, in particular for the positioning of optical waveguides, comprising:

• at least two light sources having a certain intensity distribution, said light sources being disposed one behind the other in a displacement direction;
• a pair of flat thermally coupled, optoelectronic radiation sensors disposed opposite said light source one behind the other in said displacement direction so that each of said light sources illuminates a corresponding of said radiation sensors and each of said radiation sensors delivers an output signal in dependence of said illumination;
• an electronic measuring circuit connected to said radiation sensors and forming the difference of said output signals of said two radiation sensors;
• a diaphragm disposed between said light sources and said radiation sensors, said diaphragm being displaceable in said displacement direction, and said diaphragm being operable so that, in the case of a displacement of said diaphragm in one direction, the illuminated area of one of said radiation sensors is increased, while the illuminated area of the other of said radiation sensors is correspondingly reduced;
• besides each one of said radiation sensors a reference sensor which is fully illuminated by the respective one of said light sources in each position of said diaphragm;
• a regulating circuit connected to each of said reference sensors and delivering a regulated current through the respective of said light sources;
• and
• a correction filter having transmissive filter areas for respective of said light sources, said correction filter being fixedly disposed between the respective of said light sources and said radiation sensors, and the transmission of said correction filter varying over said filter areas so that inhomogenities in said intensity distribution of said light sources are specifically eliminated.