定量相衬法研究

Quantitative study of phase contast method

本文以矩形和锯齿形相位光栅为样品，运用傅里叶光学的理论方法，对传统的相衬法进行定量研究。研究结果表明：在物的相位变动范围（０—π／２），对于相移值π／４，π／３，π／２三种情况，均能获得较好的准线性转换；当π／２时，转换灵敏程度最高：π／４时转换线性最好；π／３时两项指标居中；当物的相位变动范围超过π／２，则转换将严重地背离准线性关系，甚而相衬法完全无效。然而，实际样品的相位起伏可能是很大的。上述否定结果表明，传统的相衬法注定只能对样品作定性的图象观察，不可能对任意大相位变化的样品作定量的相位恢复。

In this Paoer taking the samples of rectangle phase gratings and saw-tooth phase gratings, we have deduced the Spectral functions and plotted a series of curves for the power spectra and the intensities produced by the phase contrast method. The results show that the quasi-linear coversion between phase and intensity distribution can obtained when the phase depth of an object in limited to (o-π / 2) domain, but the phase shift value δ of the phase plate may be taken π / 3 or π/2;when δ = π / 4. the convension linearity is the best: when δ= π / 2, the conversion sensitivity is the greatest; when δ = π / 3, the above two performances are in the middle.If the phase depth is extended to more than π/2. the phase-inensity conversion devites seriously the guasi-linear relationship even the phase contrast method fails entirely.