Research And Design On Small Angle Measuring Instrument

Angle is an important geometric parameter, also angle measurement is an important component of geometric measurement, and especially the small angle measurement has played an important role in precision testing, precision machining, and positioning systems. Currently photoelectric autocollimator has been mostly used in small-angle measurement, the accuracy can meet the requirement, but most of these devices are larger, expensive, thus it is necessary to research a portable, compact and high-precision measuring instrument.The most method of angle measurement has used photoelectric non-contact measurement, in which auto-collimation measurement is simple in structure, easies to use, has high accuracy, and it is easy to automate and miniaturize. This paper discusses the theory of self-collimation measurement to designs the self-collimation optical system, finally make a one-dimensional small angle measuring instrument, using position sensor detector (PSD) as a position detector, MSP430F149 as an embedded processor.This paper mainly expounds the design of optical system, the circuits of signal processing in hardware and software. Taking PSD as a position detector to translate the location of the signal into electrical signals, the electrical signal is very weak, it would be amplificated, filted and A/D converted, input to the MSP430 for data processing, it could be calculated the angle according to the position values. The design of PSD processing circuit based on digital calculation, so it makes the hardware simplify and avoids noise and accuracy problems which is caused by analog devices computing. Using MSP430 as an embedded processor and using curve fitting method, it improves the accuracy of angle measurement; it communicates with PC through RS232 to achieve automation of data collection.