MTF Measurement Technology Research

The optical transfer function has now become one of the most objective and mosteffective method of evaluation of optical systems image quality. And the optical transferfunction of the modulation transfer function (MTF), which is main basis of the imagingquality of the imaging quality to judge the lens and optical elements. There have manyMTF measurement instrument at home and abroad. There have been many large,multi-function, high-precision MTF measurement instrument at home and abroad. Thispaper analyzes these instruments advantages and disadvantages, and puts forward the MTFmeasurement method is suitable for small and medium-sized business and school teachingexperiment. This method uses a CCD take a picture on the LCD screen which outputs achanging frequency cosine grating, then deal with the shooting to the grating image, and getthe value in the corresponding frequency, eventually get the MTF values.This article consists of the following aspects of the word:1. A detailed study of theprinciples and method of MTF measurement;2.Choosing of the cosine functiongrating, and making the raster image contrast is one.3. Writing system software torealize the CCD camera raster image;4.Recognizing source of error in themeasurement process;5.Discussing uniformity of the LCD background light,background noise, and focus;6.Presenting from both hardware and software toimprove the measurement accuracy, and pointing out to correct result (MTF values)at the end of the measurement;7.Operating the software interface to get frequencyof the MTF value;8.Measuring the MTF of the monochromatic grating;9.FittingMTF curve.Experimental results show that MTF measurement method proposed in thispaper be achieved as the MTF measurement. And it suitable or small andmedium-sized enterprises and the teaching experiment, and it has a goodrepeatability.