An all optical ultraminiaturized sensor head for displacement measurement that has a size of less than 5 mm in square has been produced. The sensor works by means of optical triangulation. To achieve the optical function, the sensor consists of a three-layer polymer waveguide patterned by deep x-ray lithography (LIGA), a light input fiber, two detection fibers, and microcylindrical lenses, which are also fabricated by deep x-ray lithography. The fibers and the cylindrical lenses are placed into the waveguide without any active alignment by using the waveguide walls as guiding and fixing structures. The ratio of the intensities detected in the two detection fibers is the measure of the distance between the object and the sensor. High resolution of about 10 μm is achieved in the range of 2 to 3 mm between the sensor and an object with a diffusively reflecting surface.
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