Hyperspectral imaging with a TWINS birefringent interferometer

Abstract

We introduce a high-performance hyperspectral camera based on the Fouriertransform approach, where the two delayed images are generated by the Translating-Wedge-Based Identical Pulses eNcoding System (TWINS) [Opt. Lett. 37, 3027 (2012)], a commonpath birefringent interferometer that combines compactness, intrinsic interferometric delay precision, long-term stability and insensitivity to vibrations. In our imaging system, TWINS is employed as a time-scanning interferometer and generates high-contrast interferograms at the single-pixel level. The camera exhibits high throughput and provides hyperspectral images with spectral background level of −30dB and resolution of 3 THz in the visible spectral range. We show high-quality spectral measurements of absolute reflectance, fluorescence and transmission of artistic objects with various lateral sizes.

Complementary mapping techniques to characterize the wood finish of musical instruments

“…The microscope was equipped with a 50 × objective (PL FLUOTAR L 50x/0.55, Leica, Wetzlar, Germany) and a dichroic mirror (Semrock, Brightline FF389-Di01, Rochester, NY, USA), allowing the analysis of a field of view of 205 × 250 μm 2 , with a spatial sampling pitch of 0.2 μm. The hyperspectral camera was composed of a common path birefringent interferometer (the Translating-Wedge-Based Identical Pulses eNcoding System (TWINS) [49,50]) combined with a cooled monochrome camera (Retiga R6, QImaging, Teledyne Photometrics, Tucson, AZ, USA, spectral range 300-1000 nm); the interferometer supplied high-quality interferograms which provided high-quality spectral images of the PL emission by Fourier transform [51,52]. The spectral resolution of the hyperspectral camera was set by the maximum scan delay introduced by the interferometer and could be as good as 4 nm at 600 nm wavelength.…”

A New ‘Hera’ in Hyperspectral Imaging

“…The great advantage of this FT-based hyperspectral device in terms of extremely high light throughput can also be exploited in the study of works of art and cultural heritage, where low-illuminance conditions are recommended in order not to damage the samples. In this field, Hera Iperspettrale has already been used to investigate the attribution and the dating of paintings [6], to monitor their state of conservation and to assess their authenticity [5].…”

“…As a result of an FT, the spectrum at each pixel is a continuous curve, so the number of bands is virtually unlimited, and it is not defined by the hardware. Hera Iperspettrale works in a broadband spectral region, from the UV to the near infrared (0.4 -1 μm), and it features an exceptional throughput, a high spectral accuracy, and a wide versatility of use [5]. The spectral resolution, proportional to the wavelength as in any other FT techniques, corresponds to 3 nm at 600 nm.…”

Spatio-temporal characterization of ultrashort laser beams: a tutorial

“…A birefringent delay line [136,137] has recently been used for hyperspectral imaging [138] (spatiallyresolved Fourier-spectroscopy without phase information), and we have recently implemented this scheme in an INSIGHT device as well [139].…”