Patent ID: 9488820
Filing Date: 2016-11-08
CPC Classification: G02B

Claim Text:
1. An autofocus apparatus, comprising: a light source; an optical coupler having a first port, second port, a third port and a fourth port; wherein light output from the light source is coupled to the first port and splits into a first light beam and a second light beam, the first light beam being output to the second port and the second light beam being output to the third port, and wherein the forth port is coupled to an input of a spectrometer; a first optical collimator for directing the first light beam from the second port of the optical coupler onto a sample through a dichroic mirror and a microscope objective, wherein the sample is placed on a substrate supported by an adjustable microscopy stage; a second optical collimator for directing the second light beam from the third port of the optical coupler onto a retroreflector; wherein the first light beam reflected from the sample is directed back into the second port and out of the fourth port, and second light beam reflected from the retroreflector is directed back into the third port and out of the fourth port; wherein the spectrometer output control signals to control the adjustable microscopy stage based on a parabolic fit of three peaks identified in an interference signal from the reflected first and second light beams.