An embedded image processing and feedback compensation for the vibration-resistance system using white light interferometer
Journal
Proceedings of SPIE - The International Society for Optical Engineering
Journal Volume
8321
Date Issued
2011
Author(s)
Abstract
The active interferometer has been approved as an effective architecture to increase the precision of surface profile measurement by detecting the environmental vibration and then stabilized by a piezoelectric transducer. The performance of such system can improve the accuracy within nano-meters. Most of the active interferometers have being implemented on the PC based platform because it is easy to be setup and modulized, However, the latency of image grabbing processing, mathematic algorithm and I/O trigger delay is around 10~15ms. Moreover, the latency is varying if different PCs are used. In this study, an embedded real-time controller based on the ADI Blackfin BF561 DSP microprocessor was developed to improve the performance of a vibration-resistance system using white-light interferometer. The purpose of this embedded control system is to detect the vibration and compensate it for White Light Interferometer when processing stepping photograph grabbing for surface profile measurement. A customized embedded control system with a 600 MHz high performance microprocessor, Camera Link interface, DAC circuit and UART command port has been developed. A complete command set has also been defined to communicate with PC based interferometer user interface for close-loop control. The latency has been reduced from tens of millimeters to 250 μs as tested for all the procedures from CCD trigger, image processing, to PZT control signal output. It has been proved to be useful of fixing the latency between phase detecting and compensation output. With this advantage, the response of the interferometer can accelerated so that the vibration-resistance is improved and the overall accuracy can be in the range of a few nano-meters.
SDGs
Type
conference paper