ABLATION PROFILER

摘要

A calibration system uses error data from an ablation profiler or from a topographer to adjust the operating parameters of a laser ablation system. An ablation profiler, useful in calibrating systems that perform vision correction by ablating corneal tissue, is based on a scanning white light interferometer (SWLI) system. The profiler measures a sample (14) of material that has been ablated and maps the contours of the sample (14) to compare it with a database of desired contours. The SWLI system includes a novel method of controlling the movement of the SWLI's reference surface (22) using an inexpensive electromagnet assembly with a capacitive feedback control system, a pin-hole light source to improve interference patterns, and off-axis positioning of the light source and camera to avoid specular reflections. The system also includes a method of preparing the transparent sample for measurement by applying a rear-surface opaque coating and using front-surface illumination. Alternately, samples can make use of roughened surfaces to provide the required optical properties.