A Micro Absolute Distance Measurement Method Based on Dispersion Compensated Polarized Low-Coherence Interferometry

Abstract

Micro absolute distance measurement (MADM) is widely used in industrial and military fields. To achieve high accuracy and frequency response, a polarized low-coherence interferometry (PLCI)-based method for MADM is proposed. The nearly linear relationship between the envelope center and m-order PLCI fringe (PLCIF) peak center is found and verified. Dispersion compensation is achieved by fringe peak position estimation and polynomial fitting to get rid of the dependence on an a priori model and birefringence parameters, and make this method very robust. Meanwhile, the zero-order PLCIF center is estimated and located to demodulate the measured displacement. Then, the measurement accuracy is raised by polynomial fittings. In comparison to conventional methods, the proposed method can effectively avoid jump errors and has a higher accuracy. Experimental results indicate that the measurement accuracy is higher than 19.51 nm, the resolution is better than 2 nm, and its processing data rate can reach 35 kHz.

Extended centroid position method in liquid-crystal-based interrogation system for electric-field-modulated Fabry-Perot sensing

“…The resultant PLCI signal of the interference fringe pattern is a modulated version of the Gaussian spectrum (broadband white light source) with the multiple beam interference intensity of the sensing interferometer. Therefore, the light intensity formed near the thickness t of the LC wedge and the specific cavity length L of the F-P sensor can be expressed as [7,11,30]:…”

“…This results in an asymmetrical intensity distribution of the interferogram with respect to the center position at zero OPD. Considering the influence of birefringence dispersion, the resultant PLCI signal formed near the thickness t of the LC wedge and the specific cavity length L of the F-P sensor can be expressed as [7,11,32]:…”

“…Due to intriguing features such as high sensitivity, subnanoscale resolution and compact size, the potential applications of LCI are greater than those of laser interferometry. Depending on the dynamic range and the resolution of detection, LCI is regarded as the most effective technique to fulfill the specific demands of academic, industrial and military fields, and has been widely used in different fields of optical sensing [5,[7][8][9][10][11][12][13] * Author to whom any correspondence should be addressed. such as coherence scanning interferometry [2], optical coherence tomography [3], 3D surface profiling [14] and the probing of cellular morphology [4].…”

“…The advancement of this interrogator can be accomplished either by ultimate modification of the optical interferometric technique, or by the perfect development of the demodulation algorithm. This was initiated by the introduction of an air wedge by Belleville and Duplain [26] and a continuous modification in optical interferometry has now reached the level of using a small angle birefringent wedge [7][8][9][10][11] according to all the specific requirements. In addition to that, different demodulation approaches such as the envelope detection technique [8,27,28], the phasebased algorithm [20,29], the shift of the m th order fringe detection method [8] and the phase-shifting interferometric method [11] are also established towards the development of a compact and explicit sensing system.…”

All-Fiber Pulse-Train Optical Frequency-Domain Interferometer for Dynamic Absolute Distance Measurements of Vibration

“…The LCI technique has generated considerable interest in industrial applications resulting from its precise measurement of the location of a zero optical path difference. The typical types of LCI, such as Fourier domain LCI [10] and polarized LCI [11], display high speeds of up to tens of kHz with an optical detector or camera and can process the resolution and accuracy of several nanometers. However, the measuring range of LCI is achieved in millimeters due to the short coherence length of the light source.…”