Such deviated light (as you will subsequently learn, called diffracted light) is rendered one-half wavelength or 180 degrees out of step (more commonly, out of phase) with the direct light that has passed through undeviated.
Such deviated light (as you will subsequently learn, called diffracted light) is rendered one-half wavelength or 180 degrees out of step (more commonly, out of phase) with the direct light that has passed through undeviated.
这种偏移光（其后我们称之为衍射光）与直射光之间呈现半个波长或180°的不同步（一般称之为不同相位）。