Measurement of a Fiber-End Surface Profile by Use of Phase-Shifting Laser Interferometry (original) (raw)

Rapid phase-shifting fiber interferometer with optical stylus

Optics Letters, 2010

Martin, Haydn and Jiang, Xiang (2010) Rapid phase shifting fiber interferometer with optical stylus. Optical Letters, 35 (5). ABSTRACT Optical fiber interferometry holds many advantages for the online measurement of high precision surfaces. Here a fiber interferometer with a wavelength scanning probe is reported. Such an interferometer requires active stabilization against the effects of temperature drift and vibration. A method of multiplexing dual wavelengths into the same fiber, combined with rapid phase shifting and real time phase calculation is investigated. Experimental data show the successful stabilization of the interferometer regardless of environmental perturbation. OCIS codes: 120.0120, 120.3180, 120.5050. Technological advances in fields such as optics, micro-molding and micro-machining have resulted in the increased use of nano-scale and ultra-precision surfaces. The current state of online surface metrology methods for the efficient characterization of these surfaces is severely limiting both development and manufacture. Current metrology instrumentation is either too bulky, slow or damaging (in the case of touch probe methods) [1].

Development of a Surface Profiler Based on Three-Wavelength Phase-Shifting Interferometry

Proc. of JSPE Autumn Meeting, 2011

To overcome the phase ambiguity problem in phase-shifting interferometry, multi-wavelength interferometry has been long investigated. However, its industrial application has been limited because of its complex optical configurations. This paper introduces a surface profiler which uses a low-cost and simple three-wavelength imaging system consisting of a white-light illuminator, a multi-bandpass filter and a color CCD camera. The algorithms used and experimental results are presented.

Fiber-optic projected-fringe digital interferometry

A phase-stepped projected-fringe interferometer has been developed which uses a closed-loop fiber-<>ptic phase-<:ontrol system to make very accurate surface profile measurements. The closed-loop phase-<:ontrol system greatly reduces phase-stepping error, which is frequently the dominant source of error in digital interferometers. Two beams emitted from a fiber-<>ptic coupler are combined to form an interference fringe pattern on a diffusely reflecting object. Reflections off of the fibers' output faces are used to create a phase-indicating signal for the closed-loop optical phase controller. The controller steps the phase difference between the two beams by 7f/2 radians in order to determine the object's surface profi1e using a solid-state camera and a computer. The system combines the ease of alignment and automated data reduction of phase-stepping projected-fringe interferometry with the greatly improved phase-stepping accuracy of our closed-loop phase-<:ontroller. The system is demonstrated by measuring the profile of a plate containing several convex surfaces whose heights range from 15 to 25 /.Lm high.

Absolute and relative surface profile interferometry using multiple frequency-scanned lasers

SPIE Proceedings, 2016

An interferometer has been used to measure the surface profile of generic object. Frequency scanning interferometry has been employed to provide unambiguous phase readings, to suppress etalon fringes, and to supersede phase-shifting. The frequency scan has been performed in three narrow wavelength bands, each generated by a temperature tuned laser diode. It is shown, that for certain portions of measured object, it was possible to get absolute phase measurement, counting all wave periods from the point of zero path difference, yielding precision of 2.7nm RMS over 11.75mm total path difference. For the other areas where steep slopes were present in object geometry, a relative measurement is still possible, at measured surface roughness comparable to that of machining process (the same 2.7nm RMS). It is concluded, that areas containing steep slopes exhibit systematic error, attributed to a combined factors of dispersion and retrace error.

In-situ fiber-based surface profile measurement system using low coherence interferometer

Optical Sensing and Detection V, 2018

For many high-value manufacturing applications, advanced control systems are required to ensure product quality is maintained; this requires accurate data to be collected from in-situ sensors. Making accurate in-situ measurements is challenging due to the aggressive environments found within manufacturing machines and processes. This paper investigates a method to obtain surface profile measurements in a spectral-domain, common-path, low-coherence system. A fibre based Low Coherence Interferometer was built and was used to experimentally measure surface profiles. The fringes obtained from interferograms were transformed into the Fourier domain to obtain a trackable peak relating to the surface depth. This has been illustrated with ideal step height measurements and referenced specimens as well as more challenging surface roughness measurements, which have produced complex signal processing issues. This work opens up avenues for a metrology based system where both machining and measurement system can coexist on the same plane, in aggressive environments.

Development of a Surface Profiler Base on Three-Wavelength Phase-Shifting Interferometry

Proceedings of JSPE Semestrial Meeting, 2011

To overcome the phase ambiguity problem in phase-shifting interferometry, multi-wavelength interferometry has been long investigated. However, its industrial application has been limited because of its complex optical configurations. This paper introduces a surface profiler which uses a low-cost and simple three-wavelength imaging system consisting of a whitelight illuminator, a multi-bandpass filter and a color CCD camera. The algorithms used and experimental results are presented.

Surface profile analysis using a fiber optic low-coherence interferometer

2009

Several optical measurement principles have proven their potential for high-resolution surface measurements. Among a few others, white-light interferometry has proven its capability for the measurement of technical surfaces, but yet, white-light interferometer systems cannot be miniaturized enough e.g. for the measurement inside small boreholes. In this work, a fiber-optic measurement system is described. Since the measuring principle is based on lowcoherence interferometry (LCI), the system provides non-contact surface measurements with nanometer accuracy. We present a system set-up for surface profile acquisition as well as the application of the system for the determination of roughness and waviness parameters. An outstanding feature of the proposed system is the miniaturized fiber-optic sensing probe, which is built up in all-fiber design. With a probe diameter down to 800 μm, the system can be used for measurements inside small cavities, e.g. bearings or injection nozzles. Beam shaping is realized with graded-index (GRIN) fibers. Conclusively, the results of evaluation measurements are compared with ISO 5436-1 type A and D measurement standards.

An integrated optical coupler used in a fibre interferometry system for on-line surface measurements

Optics Communications, 2008

In this paper, an integrated optical (IO) coupler produced using the technique of silica-on-silicon was described. A fibre interferometry system using the IO coupler was then developed and its performance was tested. The environmental noise and disturbances in this system were reduced significantly after combining a reference interferometer and an all fibre polarisation scrambler so as to produce good stability and repeatability. Furthermore, the measurement mirror was mounted on a piezoelectric transducer (PZT) and disturbances were introduced in the system in order to simulate on-line surface measurements. Both a commercial fibre and the IO couplers were compared using this method. Better experimental results were achieved when the system using the IO coupler than using the fibre one.

In-situ fibre-based surface profile measurement system using low coherence interferometer

2018

For many high-value manufacturing applications, advanced control systems are required to ensure product quality is maintained; this requires accurate data to be collected from in-situ sensors. Making accurate in-situ measurements is challenging due to the aggressive environments found within manufacturing machines and processes. This paper investigates a method to obtain surface profile measurements in a spectral-domain, common-path, low-coherence system. A fibre based Low Coherence Interferometer was built and was used to experimentally measure surface profiles. The fringes obtained from interferograms were transformed into the Fourier domain to obtain a trackable peak relating to the surface depth. This has been illustrated with ideal step height measurements and referenced specimens as well as more challenging surface roughness measurements, which have produced complex signal processing issues. This work opens up avenues for a metrology based system where both machining and measu...