Single-shot profilometry of rough surfaces using hyperspectral interferometry

Abstract

Additional Information:• This paper was published in Optics Letters and is made avail- The combination of white light interferometry with hyperspectral imaging ("hyperspectral interferometry") is a recently proposed technique for single-shot measurement of 3D surface profiles. We consider for the first time its application to speckled wavefronts from optically rough surfaces. The intensity versus wavenumber signal at each pixel provides unambiguous range information despite the speckle-induced random phase shifts. Experimental results with samples undergoing controlled rigid body translation demonstrate a measurement repeatability of 460 nm for a bandwidth of approximately 30 nm. Potential applications include roughness measurement and coordinate measurement machine probes where rapid data acquisition in noncooperative environments is essential.

Single-shot areal profilometry using hyperspectral interferometry with a microlens array

“…The continuous trace of the transform from which the peak is extracted is shown with a continuous line and the position of the peak is indicated with a vertical line. In comparison with our previous HSI system [6,7], a much higher pixel utilisation rate is achieved because the spectra are distributed across the PDA rather than within a horizontal band less than 20 pixels high. A 100% utilisation rate is not possible because some space between spectra is required to avoid spectral crosstalk.…”

“…Known as hyperspectral interferometry (HSI), it is based on the combination of an interferometer and a hyperspectral imaging system [6,7]. HSI uses a hyperspectral imager to spatially separate a set of narrowband interferograms from a single white-light interferogram.…”

“…Prototype HSI systems and sample profiles from both optically smooth and rough surfaces have been reported in [6] and [7], respectively. A white-light image of the sample was recombined with a reference beam at the entrance of an imaging spectrometer which spread the image along a spectral axis by means of a diffraction grating.…”

High-throughput single-shot hyperspectral interferometer for areal profilometry based on microlens array integral field unit

“…Spatial smoothing was not required for these results, unlike the case for the etalon based system from Ref. [7].…”

“…The scanning nature of these approaches imposes stringent environmental stability requirements during the acquisition of typically hundreds of interferograms. To overcome this limitation, a 'single-shot' method has been proposed in which all the spatial and spectral information is recorded simultaneously in a single exposure [6][7] . Known as hyperspectral interferometry (HSI), the output of a white-light interferometer provides the input to a hyperspectral imaging system to spatially separate, onto a photodetector array, a set of narrowband interferograms from a single white-light interferogram.…”