a) Reference wave b) Amplitude Reduced object amplitude Phase c) Retarded object phase Figure 7-2 Effects of amplitude and phase objects on the waveform of light.(a)Reference ray with characteristic amplitude,wavelength,and phase.(b)A pure amplitude object absorbs energy and reduces the amplitude,but does not alter the phase,of an emergent ray.(c)A pure phase object alters velocity and shifts the phase,but not the amplitude,of an emergent ray. ·人眼可以区分振幅变 ·人眼不能区分相位变 化 化 。eg:明场、暗场 。 相位变化->振幅变化 eg:偏光、相衬、微 分干涉• 人眼可以区分振幅变 化 • eg.: 明场、暗场 • 人眼不能区分相位变 化 • 相位变化->振幅变化 • eg.: 偏光、相衬、微 分干涉 3