On-line submicron profile measurements from safe distances with conoscopic holography: feasibility and potential problems

Álvarez, Ignacio; Enguita, J.M.; Marina, Jorge; Fraga, César G.

doi:10.1117/1.2844713

Cited by 4 publications

(4 citation statements)

References 15 publications

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“…For the initial sensor prototype described in [ 20 ], a rotating diffuser was used, as it is the simplest method, but other alternatives are currently under study. The diffuser is placed after the laser unit (685 nm, 50 mW) with a small lateral displacement and slightly out of focus.…”

Section: Reaching Sub-micron Precisions: Attacking Specklementioning

confidence: 99%

On-Line Metrology with Conoscopic Holography: Beyond Triangulation

Álvarez

Enguita

Frade

et al. 2009

Sensors

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On-line non-contact surface inspection with high precision is still an open problem. Laser triangulation techniques are the most common solution for this kind of systems, but there exist fundamental limitations to their applicability when high precisions, long standoffs or large apertures are needed, and when there are difficult operating conditions. Other methods are, in general, not applicable in hostile environments or inadequate for on-line measurement. In this paper we review the latest research in Conoscopic Holography, an interferometric technique that has been applied successfully in this kind of applications, ranging from submicrometric roughness measurements, to long standoff sensors for surface defect detection in steel at high temperatures.

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Section: Reaching Sub-micron Precisions: Attacking Specklementioning

confidence: 99%

On-Line Metrology with Conoscopic Holography: Beyond Triangulation

Álvarez

Enguita

Frade

et al. 2009

Sensors

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“…Processing considerations using this method have already been reported. 12,13,15 It is possible to speed up the processing task using Phase Shifting algorithms applied just to a few rows of the fringe pattern, 16 the pattern can be seen as spatial carrier fringes with the same information coded in every row. If the processed row corresponds with the optical axis of the system, the obtained phase is ϕ 0 , otherwise the changes in the OPD due to the added distance in the vertical coordinate of the fringe pattern must be considered.…”

Section: Profilometer Working Principlementioning

confidence: 99%

“…Achievable precisions with this system range from less than one micron for standoffs of 100 mm to 0.2 mm for standoffs beyond one meter. 12,13 Although these systems have been successfully used for surface inspection and defect detection, we have experimented behaviors which cannot be explained by the simple model for fringe formation we have been using, which amongst other things, considers normal incidence of the incoming rays into the Savart plate. These deviations from the ideal case are more noticeable when dealing with high precisions from short distances, and include variations in the density of the fringes which do not relate to profile depth changes and variations in the frequency and phase signals for small defects which are either outside the system's theoretical precision or with a magnitude that does not correspond to the defect size.…”

Section: Introductionmentioning

confidence: 99%

Fringe pattern characterization by OPD analysis in a lateral shearing interferometric profilometer

et al. 2011

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A common-path interferometric profilometer using a Savart plate as a lateral shearer has been successfully tested under harsh environmental conditions to measure the shape of a surface, detecting defects and characterizing surface properties. The whole profile is obtained from a single image and its depth sensitivity is easily scalable, making this technique suitable for many different applications. Although this system has been successfully used for surface inspection and defect detection, some behaviors cannot be explained by the usual simple model for fringe formation, which, amongst other things, considers normal incidence of the incoming rays into the Savart plate. These deviations from the ideal case are more noticeable for high resolutions from short distances. This paper studies the formation of the fringe pattern, which is crucial for understanding the behavior of the system and proper calibration.

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“…Various open space and fibre based online interferometry systems for surface measurements have been demonstrated. 1,[15][16][17][18][19] These systems, especially fibre based, are extremely sensitive to external disturbances and vibrations and require complex stabilization techniques to remove measurement errors. 20 Also in terms of operating speed, they still need significant improvements.…”

Section: Introductionmentioning

confidence: 99%

Towards the development of a hybrid-integrated chip interferometer for online surface profile measurements

Kumar

Martin

Jiang

2016

Review of Scientific Instruments

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Non-destructive testing and online measurement of surface features are pressing demands in manufacturing. Thus optical techniques are gaining importance for characterization of complex engineering surfaces. Harnessing integrated optics for miniaturization of interferometry systems onto a silicon wafer and incorporating a compact optical probe would enable the development of a handheld sensor for embedded metrology applications. In this work, we present the progress in the development of a hybrid photonics based metrology sensor device for online surface profile measurements. The measurement principle along with test and measurement results of individual components has been presented. For non-contact measurement, a spectrally encoded lateral scanning probe based on the laser scanning microscopy has been developed to provide fast measurement with lateral resolution limited to the diffraction limit. The probe demonstrates a lateral resolution of ∼3.6 μm while high axial resolution (sub-nanometre) is inherently achieved by interferometry. Further the performance of the hybrid tuneable laser and the scanning probe was evaluated by measuring a standard step height sample of 100 nm.

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On-line submicron profile measurements from safe distances with conoscopic holography: feasibility and potential problems

Cited by 4 publications

References 15 publications

On-Line Metrology with Conoscopic Holography: Beyond Triangulation

On-Line Metrology with Conoscopic Holography: Beyond Triangulation

Fringe pattern characterization by OPD analysis in a lateral shearing interferometric profilometer

Towards the development of a hybrid-integrated chip interferometer for online surface profile measurements

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