OPTICAL IMAGING FOR OPTICAL DEVICE INSPECTION

摘要

An optical imaging apparatus based on optical frequency domain measurement (OFDM) collects scatter data at multiple locations within or on the DUT as a function of time. A light source launches light into a device under test (DUT) which scatters light at one or more locations along the DUT. A light detector detects a portion of light scattered at each of multiple locations along the DUT. Data is determined using OFDM data processing that corresponds to an amount of light collected at each of the multiple locations along the DUT as a function of time. The data is stored for each of the multiple locations along the DUT. User information is provided that indicates an amount of light scattered at each of the multiple locations along the DUT based on the stored time domain data. The OFDM processing permits fine time resolution (e.g., 0.1 picoseconds) that allows small optical delay distances (e.g., 30 microns) to be resolved and allows for accurate detection of small amounts of scatter (e.g., one trillionth) to be detected simultaneously with the fine time resolution.