Micro-optical distance sensor fabricated by the LIGA process

An ultra-miniaturized sensor head for absolute measurement which has a size of less than 5 mm cube is realized. The sensor works by means of the optical triangulation. To achieve the optical function, the sensor consists of a three layer polymer waveguide patterned by X-ray lithography, an incoupling fiber and two detection fibers and micro cylindrical lenses which are also fabricated by X-ray lithography. The fibers and the cylindrical lenses are placed into the waveguide without any active alignment by using waveguide walls as guiding and fixing structures. The ratio of intensity detected in the two detection fibers is a measure for the distance between the object and the sensor. The detection range of the sensor is 1 to 6 mm between the sensor and an object with diffusively reflecting surface.