Journal article

Michelson interferometer for detection of fast displacements of less than a quarter-wave over small areas

Coherent light is divided into a reference and a probing beam at a beam splitter. The reference mirror is mounted onto a piezoelectric transducer driven by a sawtooth generator triggered by a clock. The probing beam is focused by a lens onto the reflecting surface of the sample to be investigated. The ramp duration is somewhat longer than the duration of the deformation event at the sample. During the ramp, the reference mirror moves uniformly over about 2λ/3 giving a sinusoidal intensity variation at the photodetector. Two oscilloscopes of different time bases display the signal. One records the calibration signal, the other records the amplified and expanded section of the sine wave perturbed by the deformation of the sample. The lateral resolution of the interferometer is given by the focal spot diameter of the focusing system. The depth resolution (in beam direction) is determined by the SNR. Depth and time resolution are not independent variables. An investigation of the deformation of pulsed diode lasers (GaAs) is described. Displacements of 1 nm were detected with a time resolution of 40 n sec

    Keywords: displacement measurement ; light interferometers ; semiconductor lasers ; vibration measurement


    Inst. of Applied Phys., Univ. of Berne, Switzerland

    Copyright 1975, IEE



    Michelson interferometer

    reference mirror

    piezoelectric transducer

    sawtooth generator

    probing beam

    ramp duration

    sinusoidal intensity variation


    lateral resolution

    depth resolution

    fast displacement detection

    pulsed GaAs laser deformation

    coherent light

    small displacements

    oscilloscope display


    Record created on 2009-01-20, modified on 2017-05-10


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