变密度型正弦波光栅是测定感光材料调制传递函数(MTF)的仪器中的一个关键元件。该光栅的加工,主要包括制作一块变面积校正板,获得透过率特性曲线,以使胶片的非线性记录、制作系统的MTF等得到补偿。再以此曲线,作出不同频率的变积曝光板,经过投影系统、动态曝光和洗影处理,使胶片得到不同频率的、透过率按正弦变化的光栅影象。 Variable Density Sine Gratings are a key element in instruments that measure the modulation transfer function (MTF) of photosensitive materials. The processing of the grating mainly includes making a variable area correction plate and obtaining the transmittance characteristic curve so that the non-linear recording of the film and the MTF of the production system are compensated. Then with this curve, different frequency of variable exposure plate, through the projection system, dynamic exposure and scouring process, so that the film has different frequencies, the transmission rate by a sinusoidal grating image.