Optical or opto-electronic coupling - uses spherical lens received in frusto-pyramidal recess of one part and groove of other part

摘要

The present coupling uses a base plate about half a millimetre thick (14) into which a four-sided pyramidic hole is etcvhed. The top opening is about .910 mm square. A glass ball of .9 mm is placed into it. On top of this arrangement a silicon block is placed with a relatively deep recess (23) having a square cross-section, two faces of which (24) are pushed during assembly in such a manner that they just touch the glass spherical lens at two points (P1, P2). A vertical hole (21) is made in the silicon block 820) just large enough to lead a glass fibre conductor (22) through it. The position of this hole and the etched surfaces (24) are such that a light beam passing through the fibre travels through the centre of the lens and focussed upon the photo-sensitive film of the photodiode chip (7). ADVANTAGE - Makes possible inexpensive mass prodn. of transducer parts. Photodiode is well protected against damage. In the field, no further adjustment needed for focussing beam.