Testing And Controlling System Of The Equipment For Measuring Birefringence Of Infrared Crystals

The equipment for measuring birefringence of infrared crystals and especially itstesting and controlling system were deeply studied. This equipment was developed tomeasure the birefringence of infrared crystals,which would vary from the ideal valuecaused by external stress or error during manufacturing and thus would influence theimage quality of optical system. As the birefringence exceeds the fathomable range ofcommon measurements, it is necessary to propose an effective way aiming atmeasuring the infrared birefringence and develop a piece of automatic measuringequipment.In this paper, the testing and controlling system was discussed and some detailswere studied in depth, including the principles for measuring birefringence, the designof the circuit controlling this equipment, the process of testing and precisionanalysis.By analyzing the principle of Senamont, a method in the way of comparisonaiming at measuring the birefringence of infrared crystals was given in theory, and thepracticable testing process including the least error sources was discussed, with signalintensity in each step given by its algebraic expression.The design of testing andcontrolling system and the application software of this equipment were studied indetail, with the infrared intensity modulated to AC, signal real-time sampled and transformed, devices accurately positioned according to the measured intensity andthe testing process monitored by the way of real-time result displayed on the computerin the form of both data and curve. As last, the precision analysis was given on thebase of analyzing errors induced by various devices through the testing pass.By the result, the accuracy of testing a standard specimen was within±10nm byutilizing this equipment for measuring birefringence of infrared crystals, whichsatisfied the target of this equipment.