Periodic nonlinear errors caused by frequency mixing are serious obstacles for increasing the resolution of heterodyne grating interferometers. Patterson department of mechanical engineering and engineering science university of north carolina at charlotte charlotte, nc 28223 abstract a highaccuracy heterodyne measuring michelson interferometer fidmi is. To measure length with a laser interferometer the fringes are counted while displacing a mirror respectively a corner cube over the distance. We present an absolute distance measurement interferometer based on a two wavelength interferometer and a.
A heterodyne interferometer arrangement 1 comprises a twofrequency light source ls, an optical reference branch rb for producing a reference signal, an optical measuring branch mb, which. The light signal is compared with standard or reference light from a local oscillator lo that w. The method uses a simple rotating analyzer as the frequency shifter. The measurement system includes a heterodyne light source, a moving grating and a lockin amplifier for phase measurement. These changes are proportional to changes in the phase difference between the reference and unknown signals, which are measured by the phasemeter. Sensitivity analysis of periodic errors in heterodyne. Cowardb anorth carolina state university, department of electrical and computer engineering, 2410 campus shore drive, raleigh, north carolina 27606. To eliminate the periodic nonlinear errors, a spatially separated. Limitations of interpolation accuracy in heterodyne interferometry r. One of the surfaces is an optically transparent element and the other surface is a substantially nontransparent element. Simple digital phasemeasuring algorithm for lownoise heterodyne interferometry. Realtime optical detection of single nanoparticles and viruses using heterodyne interferometry anirban mitra1 and lukas novotny1,2 adapted from. Osa spatially separated heterodyne grating interferometer. Heterodyne interferometric technique for displacement control.
Heterodyne detection is often used in interferometry but usually confined to single point detection rather than widefield interferometry, however, widefield heterodyne interferometry is possible using a special camera. A heterodyne interferometer for highly sensitive vibration. Before sharing sensitive information, make sure youre on a federal government site. Osa polarization heterodyne interferometry using a simple.
Anirban mitra and lukas novotny,realtime optical detec. Heterodyne manywavelength interferometry in general combbased heterodyne interferometry in particular preliminary studies on generating cavity enhanced electro optic comb 1st workshop in metrology for long distance surveying ipq, caparica jutta mildner 12 19 sources application to absolute distance measurements. The probe and homodyne oke signals can be filtered out, leaving the heterodyne frequency signal for detection. A heterodyne interferometer arrangement comprises a twofrequency light source, an optical reference branch for producing a reference signal, an optical measuring branch, which includes an interferometer unit causing a phase rotation of the light beams in response to a length to be measured, as well as a measuring transducer arranged at the output of the interferometer unit, and a phase. The theory and the potential errors of the system are. Fullfield heterodyne interferometer for shape measurement. However, the detectors were external to the device. Heterodyne interferometry is a powerful tool for shape measurement. Phasemeter core for intersatellite laser heterodyne. More generally, these systems are expected to find applications in both ultrafine selfheterodyne spectroscopy submhz range or, by combining two fsls, in multi. Recording depth and signal competition in heterodyne. A heterodyne interferometer arrangement 1 comprises a twofrequency light source ls, an optical reference branch rb for producing a reference signal, an optical measuring branch mb, which includes an interferometer unit if causing a phase rotation of the light beams in response to a length to be measured as well as a measuring transformer means arranged at the output of said.
Realtime optical detection of single nanoparticles and. Pdf simple heterodyne laser interferometer with subnanometer. Olsonc fowler memorial laboratory, department of otolaryngology, head and neck surgery, college of physicians and surgeons of columbia university, new york, new york 10032. China abstract for most accurate dimensional measurements, polarising phase measurement interferometers with heterodyne detection or quadrature fringe. Based on the technique of dualwavelength and principle of heterodyne interferometry, a modified method for measuring the absolute distance is proposed. For more accurate measurements with increasing resolution, heterodyne interferometry two different laser frequencies has been a widely used tool. Synthetic wavelength interferometry of an optical frequency. A system and method for high speed and precision measurement of the distance between at least two near contact surfaces using heterodyne interferometry is disclosed.
Radio wavelengths are much longer than optical wavelengths, and the observing stations in radio astronomical interferometers are correspondingly further apart. Polarization heterodyne interferometry using a simple. Digital syntheticheterodyne interferometric demodulation. Surface roughness extraction by gibbs random fields of laser speckle pattern texture p. Heterodyne interferometric technique for displacement. Synthetic model of nonlinearity errors in laser heterodyne. Mar 27, 2017 the laser beam drift seriously influences the accuracy of straightness or displacement measurement in laser interferometers, especially for the long travel measurement. The homodyne interferometer single frequency using a quadrature detection is used in many applications where subnanometer resolution is not needed. The optical setup of heterodyne light source with eom. Hou swiss federal office of metrology lindenweg 50, ch3084 wabern permanent address. Jun 12, 2007 a novel method for displacement measurement is presented.
Heterodyne definition of heterodyne by the free dictionary. Transmission of the two beams through the analyzer unifies the polarization state, thereby enabling. Ep0514579a1 a heterodyne interferometer arrangement. The very large distances do not always allow any usable transmission of radio waves received at the telescopes to some central interferometry point. Heterodyne laser frequency stabilization for long baseline optical interferometry in spacebased gravitational wave detectors johannes eichholz, david b. They produce a new beam called heterodyne beat note, with the property that its frequency is f1f2. Wataru kokuyama, hideaki nozato, akihiro ohta, and koichiro hattori national metrology institute of japan nmij, national institute of advanced industrial science and technology aist, tsukuba, ibaraki 3058563, japan. To solve this problem, a heterodyne straightness and displacement measuring interferometer with laser beam drift compensation is proposed. Digital syntheticheterodyne interferometric demodulation article pdf available in journal of optics a pure and applied optics 46. The required phase steps may be chosen with unequal spacing and to extend over a range greater than 27r. Optical heterodyne detection wikimili, the free encyclopedia.
Mar 12, 2018 in our previous study, we proposed a twocolor heterodyne interferometry based on the fundamental and second harmonic sh of optical frequency combs 32. Heterodyne interferometer with unequal path lengths. In heterodyne interferometry the accuracy is partly limited by nonlinearity errors. S400 november 2002 with 359 reads how we measure reads. Electronic limitations in phase meters for heterodyne. When the bending fiber is free of any axial tensile stress, the. Optical mixing errors in a fiberoptic coupled heterodyne interferometer liang zhang, steven r. The theory and the potential errors of the system are analyzed. Alternative method of wavelength drift free dualwavelength. Optical heterodyne grating interferometry for displacement. Optical mixing errors in a fibercoupled heterodyne.
For more accurate measurements with increasing resolution, heterodyne interferometry. Optically heterodyned laser interferometry, as applied to measuring linear displacements, requires different optical frequencies to be encoded onto unique polarization states. These changes are proportional to changes in the phase. A heterodyne interferometer for high resolution translation and tilt. These errors are caused by laser polarization state errors and errors of optical components, including alignment. Pdf we describe a simple heterodyne laser interferometer that has. Digital averaging phasemeter for heterodyne interferometry. Heterodyne interferometry at the singlephoton level. Two free flying test masses on each satellite represent the end mirrors of the interferometer. We describe a heterodyne interferometry system based on a complementary metaloxide semiconductor digital signal processor cmosdsp camera that is utilized for full.
Hariharan di y ision of applied physics csiro sydney, australia 2 1. Generalized data reduction for heterodyne interferometry. High precision metrology systems based on heterodyne interferometry can measure position and attitude of objects to accuracies of. Introduction heterodyning interferometry is the process through which two linearly polarised coherent laser beams of different frequencies, f1 and f2 are being superimposed. Tanner, and guido mueller department of physics, university of florida, po box 118440, gainesville, florida 32611, usa received 31 march 2015. A generalized algorithm for use with digital heterodyne or fringescanning interferometers was developed that removes many of the restrictions that had previously applied to the data collection scheme. To eliminate the periodic nonlinear errors, a spatially separated heterodyne grating interferometer is proposed in this study. Pdf heterodyne interferometer with unequal path lengths. The laser beam drift seriously influences the accuracy of straightness or displacement measurement in laser interferometers, especially for the long travel measurement. Because two test lights suffer from the same influence of wavelength drift in the measurement setup, the minus effect coming from the wavelength drift can be offset. Us6710881b1 heterodyne interferometry for small spacing. Heterodyne interferometric technique for displacement control at the nanometric scale suat topcu,a luc chassagne,b darine haddad,c and yasser alaylid laboratoire liris, universite. Cowardb anorth carolina state university, department of.
Pdf digital syntheticheterodyne interferometric demodulation. The measurement needs to be performed with a noise level of. Periodic error correction in heterodyne interferometry. Introduction heterodyne displacement measuring interferometry offers accurate, highresolution displacement measurement for noncontact applications. Jun 19, 2010 based on the technique of dualwavelength and principle of heterodyne interferometry, a modified method for measuring the absolute distance is proposed. The light signal is compared with standard or reference light from a local oscillator lo that would have a fixed offset in frequency and. Digital heterodyne interferometry, proceedings of spie 10. A heterodyne interferometric system based on optical polarization is described. Optical heterodyne detection is a method of extracting information encoded as modulation of the phase, frequency or both of electromagnetic radiation in the wavelength band of visible or infrared light. Differentialpath interferometry is used extensively in situations requiring accurate displacement measurements. Heterodyne manywavelength interferometry jutta mildner 1, karl meinershagen 1 and florian pollinger 1 1 physikalischtechnische bundesanstalt ptb, bundesallee 100, 38116 braunschweig. The intensity of the signal from the interference of a leaked beam and a measurement beam as a ratio of the measurement signal is described by equation 2.
Simple digital phasemeasuring algorithm for lownoise. Beijing institute of machine building industry, beijing, p. Chapter 21 handbook of optics photonics research group. A novel method for displacement measurement is presented. A heterodyne interferometer for high resolution translation and tilt measurement as. The applications of the heterodyne interferoemetry 35 fig. Heterodyne interferometry uses beats produced by superposing two light waves with different frequencies at a photodetector. Our new concept for heterodyne interferometry takes advantage of the frequency comb recently decorated with the nobel prize 4.
Integrated heterodyne interferometer with onchip modulators. One implementation of this approach, called the digital heterodyne interferometer, uses. A heterodyne straightness and displacement measuring. A novel heterodyne interferometer for millimetre and submillimetre astronomy paul k. Heterodyne interferometry relies on interfering the stellar light with the light of a local oscillator, basically a monochromatic laser, producing a beat signal with a frequency in the radio range. Heterodyne interferometry using two wavelengths for dimensional. Knowing amplitude and phase of the local oscillator. If ximt is constant and noise free, ximf has all its power at f 0 and eq. Two modulated beams with different frequencies are transferred respectively by two fibers, which form a spatially separated. Heterodyne interferometry is a widely used and highly sensitive method for measuring.
The optical phase variation, which stems from the grating movement, is measured by an optical heterodyne interferometer. Such a configuration is free from periodic errors associated with frequency mixing. Commercially available configurations for differentialpath interferometers include, but. Heterodyne interferometry with a frequency comb the. Osa polarization delivery in heterodyne interferometry. The output from the photodetector then contains a component at the beat frequency which can be processed to obtain information on changes in the optical path difference. The ratio of the free spectral range to the width of the fringes at half maximum. High precision metrology systems based on heterodyne interferometry can measure position and attitude of objects to accuracies of picometer and nanorad, respectively. The heterodyne frequencies were generated using an onchip mode converter and phase modulator.
To eliminate nonlinear contributions to the interferometer signal, the frequency difference must be introduced after beam splitting and the interfering beams must be recombined via spatially separated paths. Heterodyne detection is often used in interferometry but usually confined to single point. Heterodyne laser interferometry is used to convert the path length variations into phase shifts of the heterodyne beat note 2. However, there are currently only few papers devoted to fullfield, timedependent heterodyne interferometry. In particular, heterodyne and homodyne interferometry can accurately measure particle velocity and displacements at a specific point in space thus enabling the acoustical. Having alternating currents of two different frequencies that. A heterodyne laser interferometeris used to measure changes in the length of the optical path between the cornercube retroreflectors. A comparison between heterodyne and homodyne interferometry. Integrated heterodyne interferometer with onchip modulators and detectors david b. Commercially available configurations for differentialpath interferometers include, but are not limited to, single frequency homodyne and dual frequency heterodyne. In our previous study, we proposed a twocolor heterodyne interferometry based on the fundamental and second harmonic sh of optical frequency combs 32. Digital heterodyne interferometry digital heterodyne interferometry massie, n. Limitations of interpolation accuracy in heterodyne.
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