We have developed a new implementation of a Michelson interferometer which has demonstrated better than 20 picometer resolution measurement capability. This new method uses a tunable diode laser as the light source with the laser wavelength continuously tuned so the fringe pattern is locked on a zero crossing. The diode laser is beat against a reference laser and the beat frequency is the measured signal. The ability to make high speed, accurate frequency measurements of the beat frequency signal enables the control signal of the diode laser to be tracked with an accuracy enabling nominally 20 picometer resolution and accuracy. The new interferometer design is light weight and has been mounted directly on an ultra high vacuum scanning tunneling microscope capable of atomic resolution. In this paper, we report the simultaneous acquisition of an atomic resolution image while the relative tip to sample distance is measured with the new tunable diode laser Michelson interferometer.
Citation: Optical Engineering
Issue: No. 1
Pub Type: Journals
10 picometer resolution, accurate frequency measurements, Micelson interferometer, tunable diode laser, ultra high va