Interferometry with optical pickups

We describe an interferometer that makes use of an optical pickup. This widespread consumer electronics component has a high degree of technological content. A typical head contains a remarkable, highly integrated sample of optoelectronic laboratory equipment. The application that we report is a significant and novel example of the potential exploitation of the unique features of such a device for scientific aims. Many interferometric configurations can be envisaged, depending on the specific pickup design. We present a Fizeau multiphase homodyne interferometer that makes use of an astigmatic-focus-detection pickup. Its quadrant detector provides four photocurrent signals whose phase delays can be easily controlled. This allows us to apply phase-shifting interferometry algorithms for data reduction.