A sinusoidal phase-modulating (SPM) laser diode (LD) interferometer for real-time surface profile measurement is proposed and its principle is analyzed. The phase signal of the surface profile is detected from the sinusoidal phase-modulating interference signal using a real-time phase detection circuit. For 60*60 measurement points of the surface profile, the measuring time is 10 ms. A root mean square (RMS) measurement repeatability of 3.93 nm is realized, and the measurement resolution reaches 0.19 nm.

A scanning Hartmann test method is proposed and its measurement principle is described. The scanning Hartmann test setup is formed by modifying the Hartmann screen of the conventional Hartmann test setup. With the rotation of the scanning Hartmann screen and the improved hole arrangement, the whole information of the lens to be tested in the full aperture can be obtained. The measurement accuracy of the aberration is improved and the local error of the lens can be got. In the method, no change of the Hartmann screen is needed for measuring the lenses of different aperture sizes. Experimental results of aberration measurements of two lenses are given to verify the usefulness of the setup.