Vibration Insensitive Interferometry (original) (raw)

Vibration-resistant phase-shifting interferometry

Applied Optics, 1996

A method to reduce the sensitivity of phase-shifting interferometry to external vibrations is described. The returning interferogram is amplitude split to form two series of interferograms, taken simultaneously and with complementary properties, one with high temporal and low spatial resolution and the other with low temporal and high spatial resolution. The high-temporal-resolution data set is used to calculate the true phase increment between interferograms in the high-spatial-resolution data set, and a generalized phase-extraction algorithm then includes these phase increments when the topographical phases in the high-spatial-resolution data set are calculated. The measured topography thereby benefits from the best qualities of both data sets, providing increased vibration immunity without sacrificing high spatial resolution.

Phase-shifting interferometry based on induced vibrations

Optics Express, 2011

The presence of uncontrolled mechanical vibrations is typically the main precision-limiting factor of a phase-shifting interferometer. We present a method that instead of trying to insolate vibrations; it takes advantage of their presence to produce the different phase-steps. The method is based on spatial and time domain processing techniques to compute first the different unknown phase-steps and then reconstruct the phase from these tilt-shifted interferograms. In order to compensate the camera movement, it is needed to perform an affine registration process between the different interferograms. Simulated and experimental results demonstrate the effectiveness of the proposed technique without the use of any phase-shifter device.

Analysis of a micropolarizer array-based simultaneous phase-shifting interferometer

Applied Optics, 2005

Recent technological innovations have enabled the development of a new class of dynamic (vibrationinsensitive) interferometer based on a CCD pixel-level phase-shifting approach. We present theoretical and experimental results for an interferometer based on this pixelated phase-shifting technique. Analyses of component errors and instrument functionality are presented. We show that the majority of error sources cause relatively small magnitude peak-to-valley errors in measurement of the order of 0.002-0.005. These errors are largely mitigated by high-rate data acquisition and consequent data averaging.

Suppressing phase errors from vibration in phase-shifting interferometry

Applied Optics, 2009

A new method for reducing the influence of vibrations in phase-shifting interferometry uses spatial information to achieve a 100X reduction in vibrationally induced surface distortion for small-amplitude vibrations. The technique does not require high density spatial carrier fringes and maintains full lateral sampling resolution. The principles of the technique are discussed and calculations highlight the capabilities, supported by real measurements under a variety of vibration conditions.

Numerical simulations of vibration in phase-shifting interferometry

Applied Optics, 1996

Computer simulations predict the expected rms measurement error in a phase-shifting interferometer in the presence of mechanical vibrations. The simulations involve a numerical resolution of a nonlinear mathematical model and are performed over a range of vibrational frequencies and amplitudes for three different phase-shift algorithms. Experimental research with an interference microscope and comparison with analytical solutions verify the numerical model. r 1996 Optical Society of America

Punctuated quadrature phase-shifting interferometry

Optics Letters, 1998

We describe a method and algorithm for reducing the sensitivity of phase-shifting interferometry to external vibrations. Using an interline-transfer camera, a shutter, and a fast phase shifter, we acquire a series of paired interferograms in quadrature, with the pairs spaced to maximize residual phase-error cancellation. The rapid acquisition of quadrature pairs significantly improves resistance of interferometry to low-frequency vibrations.

Vibration-resistant direct-phase-detecting optical interferometers

Applied Optics, 1997

Two dual-beam differential direct-phase-detecting optical interferometers for scanning moving surfaces are described. Two beams from these interferometers are focused ϳ42 m apart on moving surfaces, and the difference in their reflected path lengths is measured to provide the surface roughness measurement. These interferometers are exceptionally insensitive to environmental vibrations and to surface physical and chemical factors. Applications discussed include the measurement of the surface roughness of a rotating cylinder and a moving web.

Optical Phase Shift Measurements in Interferometry

International Journal of Optoelectronic Engineering, 2013

The precision and accuracy of optical phase-shifting technique is critical and affects the accuracy of optical measurements undertaken using phase-shifting interfero meters. The accuracy of optical phase shifters is limited by the inherent characteristics of the piezo-actuators (or PZT) such as nonlinearit ies, hysteresis, creep and thermal d rift. Th is paper explores a new phase-shifting technique based on two acousto-optic modulators (AOMs) where the inherent characteristics of the PZT do not affect the required phase-shifts. The acousto-optic phase-shifting technique was successfully applied to control and measure the required optical phase shifts directly in the Mach-Zehnder interfero meter. This was accomplished by varying the phase delays between the two AOMs driv ing signals. In the experiment both Dual Trace and Lissajous Figures techniques were used to determine the behavior of the optical phase shifting system in terms of accuracy and repeatability.

Phase-shift-amplified Interferometry

Optics Letters, 2018

We present a new technique for improving the sensitivity of an interferometer, phase-shift-amplified interferometry (PAI), which is based on two embedded interferometers. The internal interferometer, which is biased in anti-phase, amplifies the phase shift; the external interferometer converts this into an amplified intensity shift. PAI can improve the sensitivity of standard interferometers by an order of magnitude or more. The theory of PAI, including its enhanced immunity to relative intensity noise, phase noise, and other post-detection noise and distortion components, is presented. We experimentally demonstrate a phase-shift amplification factor of 11.