A range of sources are investigated to determine their suitability for low coherence speckle interferometry. Sources include a superluminescent diode (SLD), a multimode laser diode (MMLD) and two MMLDs. The coherence lengths for each are determined using a Michelson interferometer and are then compared with those obtained from a speckle interferometer. Two MMLDs at 792nm and 812nm are found to provide a coherence length of 10.2 micrometers comparable with that of the SLD. The dual MMLD source arrangement provides ten to a hundred times greater optical power on the test object making the technique viable for large area test objects.

Date Published: 17 September 1997
PDF: 8 pages
Proc. SPIE 3098, Optical Inspection and Micromeasurements II, (17 September 1997); doi: 10.1117/12.281175

Published in SPIE Proceedings Vol. 3098:
Optical Inspection and Micromeasurements II
Christophe Gorecki, Editor(s)