Research Of Laser Confocal Ultra-long Focal Length Measuring And Control Technology

The measurement and calibration of long focal-length on the large optics are difficult in the optical measurement field, and it is an urgent need in such national key projects as high energy laser weapon, laser fusion project and high-resolution earth observation. There still is a gap between China and other countries in the aspects of the large optical system research and large optics detection. In order to detect the large optics effictively, the lab proposed large-aperture ultra-long focal length measurement and its system by laser confocal techniques based on measuring priciple of the combined focal length measurement. This method has the characteristics of simple mechanism, stable system, short measurement distance and high measurement accuracy.This paper proposed the measurement and control technology of the large-aperture ultra-long focal length measurement and its system by laser confocal techniques, this technic uses the characteristic that the system focus corresponds to the confocal response curve, by controling the base hardware we can draw the confocal curve after scaning the facula with the high and fast scanning technic, we can measure the front and rear surface of the reference len, the focus variation of the reference lens with or without ultra-long focal-length lens, then the these measured parameters average value and standard deviation can be obtained after repetition measurement, we can use the focal length of test lens that calculated by the measured parameters to evaluate the measure pricision of the measurement system.The research of this paper is supported by National Instrument Program of “laser differential confocal measurement instrument development and its application research”(2011YQ040136).The main research works include:1) Proposing the measurement and control technology of ultra-long focal length measurement and its system by laser confocal techniques. Analysing the principle of long focal length measurement and the system structure and propose the measurement and control technology of measurement and control technology.2) Researching the key technologies of ultra-long focal length measurement system, including the user interface development technology based on Visual Studio 2010, the spot scanning algorithm and filtering algorithm, Acquisition camera control technology and interferometric ranging control technology, high precision scannig thechnology and Collection data processing and storage technology.3) Developing two sets of ultra-long focal length measurement software. We protocol software system design project based on the long focal length measurement project, comple the software on the Visual C++ 6.0 and Visual Studio 2010, the two sets of ultra-long focal length measurement software have been completed after many times of compling and testing, the friendly software interaction achieves the demand.4) System test and experimental verification. We build and test the ultra-long focal length measurement device to verify the software system.