Compressive sensing spectrometry based on liquid crystal devices

Abstract

We present a new type of compressive spectroscopy technique employing a liquid crystal (LC) phase retarder. A tunable LC cell is used in a manner compliant with the compressive sensing (CS) framework to significantly reduce the spectral scanning effort. The presented optical spectrometer consists of a single LC phase retarder combined with a single photo detector, where the LC phase retarder is used to modulate the input spectrum and the photodiode is used to measure the transmitted spectral signal. Sequences of measurements are taken, where each measurement is done with a different state of the retarder. Then, the set of photodiode measurements is used as input data to a CS solver algorithm. We demonstrate numerally compressive spectral sensing with approximately ten times fewer measurements than with an equivalent conventional spectrometer.

Etalon Array Reconstructive Spectrometry

“…In the case of compressive sensing171819, minimization of the L1 norm converges to a sparse solution2021, and so using a compressive sensing reconstruction algorithm is well-suited to signals that can be efficiently represented in a relatively small number of measurements (or ‘sparse’) in some basis, a condition that is true for most natural signals of interest, including spectrometry2223. In addition, this disassociation of the number of measurements from the number of data points in the recovered signal allows for a great deal of flexibility in the sensing pattern, as well as sensitivity and data compressibility.…”

Single-pixel spectroscopy via compressive sampling

“…Alternatively, in [6] it is presented a method that performs CS spectral multiplexing directly in the spectral domain without the need for spectral-to-spatial conversion ( Fig. 1).…”

“…Detector Bi re fri ng en t m at er ia ls The key concept in [6] is in contrast to the classical methods of using narrow band pass filters devices. In [6] it is suggested to scan the entire spectrum with a combination of harmonic like functions.…”

“…In [6] it is suggested to scan the entire spectrum with a combination of harmonic like functions. This Multiplexing in the spectral domain can be performed by passing the polychromatic light through a tunable periodic structure or through an alternating thin film structure and using optical photon counter.…”

Hurdles in the implementation of compressive sensing for imaging and ways to overcome them

“…CI techniques have been developed for motion tracking15 , spectral imaging16 , holography 17 , tomography18,19 , optical encryption 20 , and many other tasks. An overview of CI techniques may be found in Ref 3…”