DE1943900

1276746 Photo-electric apparatus NIPPON SELFOC K K 27 Aug 1969 [30 Aug 1968(2)] 42597/69 Heading G1A [Also in Division G2] A photo-electric converter includes a converging light guide 14 having a refractive index variation in a plane perpendicular to the optic axis according to the equation n r = n o (1-ar2) where n o is the value at the optic axis, n r the value at a radial distance r from the axis, and "a" is a positive constant. In a photo-detecting arrangement, the junction 17 of a reverse biased PN junction device 16 e.g. a photo-transistor, or the corresponding contact portion of a point contact device is positioned at the point at which an incident paraxial light beam is focused by the guide. If the guide has an axial length (2n+1)# /2 #2 a the element may be positioned in contact with the guide.