Absolute distance measurement with micrometer accuracy using a Michelson interferometer and the iterative synthetic wavelength principle

Abstract

We present a novel system that can measure absolute distances of up to 300 mm with an uncertainty of the order of one micrometer, within a timeframe of 40 seconds. The proposed system uses a Michelson interferometer, a tunable laser, a wavelength meter and a computer for analysis. The principle of synthetic wave creation is used in a novel way in that the system employs an initial low precision estimate of the distance, obtained using a triangulation, or time-of-flight, laser system, or similar, and then iterates through a sequence of progressively smaller synthetic wavelengths until it reaches micrometer uncertainties in the determination of the distance. A further novel feature of the system is its use of Fourier transform phase analysis techniques to achieve sub-wavelength accuracy. This method has the major advantages of being relatively simple to realize, offering demonstrated high relative precisions better than 5 × 10(-5). Finally, the fact that this device does not require a continuous line-of-sight to the target as is the case with other configurations offers significant advantages.

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

“…Micro absolute distance measurement (MADM) is widely used in industrial and military fields, such as surface profile measurement, optical coherence tomography, and optical fiber sensing applications such as pressure in hash environment, refractive index, and thickness of transparent materials [1][2][3][4]. Absolute length interferometers are known as being highly specialist, capable of being operated only under strictly controlled environmental conditions and are also very expensive [5][6][7]. However, recent developments in low-coherence interferometry (LCI), in particular its convenience of relatively low cost, light weight and high response, have led to an upsurge in interest in this area.…”

“…A BOW of 1.5 mm in thickness and 4 • in wedge angle is designed which could be easily manufactured by standard process. Conventional intensity-based peak or phase-based detection algorithms cannot be directly utilized in PLCI, which would lead to misidentification of the fringe order and cause jump errors [5,14]. Several researches have been done in this particular issue.…”

A method for long absolute distance measurement based on high stability and synchronous multi-frequency

“…Phase-shift laser range finder is one of the commonly used methods, which is based on detecting phase difference of measuring frequency between references beam and reflecting beam 1 . Therefore the stability of the measuring frequency has important implication on the measurement accuracy.…”

Measurement of air refractive index fluctuation based on interferometry with two different reference cavity lengths

“…The key point is to obtain a proper synthetic wavelength by combining two or more individual wavelengths [5,6]. The method is normally applied in length measurement [7][8][9], and some researchers have applied it in air refractive index measurement [10,11]. However, many practical applications of synthetic wavelength principle are limited, for the number of laser wavelengths meeting corresponding requests is fixed especially for measuring lasers that need good qualities of frequency stabilization and beam mode.…”