Patent ID: 6304332
Filing Date: 2001-10-16
Classification: G01B

Abstract:
Apparatus for measuring the period of a grating structure formed on a semiconductor device, the apparatus comprisinga rotatable mounting fixture for holding an optoelectronic device to be measured;a laser source for providing output pulsed radiation, said laser source disposed with respect to said rotatable mounting fixture such that the output pulsed radiation impinges a grating structure of a mounted optoelectronic device;a first photodetector disposed to capture a diffracted output beam produced by the interference of the output pulsed radiation with the grating structure;a second photodetector disposed to capture a retroreflected beam from said grating for determining a starting point for subsequent measurements supplied by the first photodetector;a plurality of amplifiers coupled to the photodetectors for generating electrical representations of the detector optical signals; anda computer-controlled data collector coupled to the plurality of amplifiers for translating the electrical representations into an associated grating period.