Design considerations and validation of the MSTAR absolute metrology system

Absolute metrology measures the actual distance between two optical fiducials. A number of methods have been employed, including pulsed time-of-flight, intensity-modulated optical beam, and two-color interferometry. The rms accuracy is currently limited to ~5 microns. Resolving the integer number of wavelengths requires a 1-sigma range accuracy of ~0.1 microns. Closing this gap has a large pay-off: the range (length measurement) accuracy can be increased substantially using the unambiguous optical phase. The MSTAR sensor (Modulation Sideband Technology for Absolute Ranging) is a new system for measuring absolute distance, capable of resolving the integer cycle ambiguity of standard interferometers, and making it possible to measure distance with sub-nanometer accuracy. In this paper, we present recent experiments that use dispersed white light interferometry to independently validate the zero-point of the system. We also describe progress towards reducing the size of optics, and stabilizing the laser wavelength for operation over larger target ranges. MSTAR is a general-purpose tool for conveniently measuring length with much greater accuracy than was previously possible, and has a wide range of possible applications.

[1]  R L Byer,et al.  Iodine spectroscopy and absolute frequency stabilization with the second harmonic of the 1319-nm Nd:YAG laser. , 1993, Optics letters.

[2]  K. Seta,et al.  High-resolution distance meter using optical intensity modulation at 28 GHz , 1998 .

[3]  R. Thalmann,et al.  Two-Wavelength Laser Interferometry Using Super-Heterodyne Detection , 1987, Other Conferences.

[4]  N. Bobroff.  Recent advances in displacement measuring interferometry , 1993 .

[5]  R. Hatch.  The synergism of GPS code and carrier measurements , 1982 .

[6]  R. Dändliker,et al.  Two-wavelength laser interferometry using superheterodyne detection. , 1988, Optics letters.

[7]  John L. Hall,et al.  Laser phase and frequency stabilization using an optical resonator , 1983 .

[8]  Dai Xiaoli,et al.  High-accuracy absolute distance measurement by means of wavelength scanning heterodyne interferometry , 1998 .

[9]  H. K. Wickramasinghe,et al.  Absolute optical ranging with 200-nm resolution. , 1989, Optics letters.

[10]  F. Zhao.  Demonstration of sub-angstrom cyclic nonlinearity using wavefront-division sampling with a common-path laser heterodyne interferometer , 2001 .

[11]  P. Groot.  Three-color laser-diode interferometer. , 1991 .

[12]  Olivier Bock.  Relative positioning precision of the wide-angle airborne laser ranging system , 1999 .

[13]  Lowell P. Howard,et al.  Diode Lasers in Length Metrology: Application to Absolute Distance Interferometry | NIST , 1999 .

[14]  Ronald N. Bracewell,et al.  The Fourier Transform and Its Applications , 1966 .

[15]  R. Spero,et al.  Multichannel averaging phasemeter for picometer precision laser metrology , 1999, Other Conferences.