Binary Complementary Filters for Compressive Raman Spectroscopy

Abstract

The previously described optimized binary compressive detection (OB-CD) strategy enables fast hyperspectral Raman (and fluorescence) spectroscopic analysis of systems containing two or more chemical components. However, each OB-CD filter collects only a fraction of the scattered photons and the remainder of the photons are lost. Here, we present a refinement of OB-CD, the OB-CD2 strategy, in which all of the collected Raman photons are detected using a pair of complementary binary optical filters that direct photons of different colors to two photon counting detectors. The OB-CD2 filters are generated using a new optimization algorithm described in this work and implemented using a holographic volume diffraction grating and a digital micromirror device (DMD) whose mirrors are programed to selectively direct photons of different colors either to one or the other photon-counting detector. When applied to pairs of pure liquids or two-component solid powder mixtures, the resulting OB-CD2 strategy is shown to more accurately estimate Raman scattering rates of each chemical component, when compared to the original OB-CD, thus facilitating chemical classification at speeds as fast as 3 μs per measurement and the collection of Raman images in under a second.

Application of digital micromirror devices (DMD) in biomedical instruments

“…Owen G presented an optimized binary compressive detection strategy in which all of the collected Raman photons are detected using a pair of complementary binary optical¯lters that direct photons of di®erent colors to two photon counting detectors. 61 This new strategy (OBCD2) uses two detectors to count all of the collected photons transmitted by two complementary binary optical in Fig. 9.…”

“…Schematic of the OB-CD2 Raman system with a 532 nm excitation laser. 61 fundus, as well as cornea, lens, vitreous°uid, and aqueous humor. It is employed to evaluate symptoms of various retinal vascular diseases or eye diseases such as glaucoma and retinal detachment.…”

Applications of Spatial Light Modulators in Raman Spectroscopy

“…32 detection of Raman spectroscopy was also realized using two types of SLM: LC-SLM 33 and DMD. [34][35][36][37] Here we will briefly introduce the LC-SLM based system, as the DMDbased system will be presented in the amplitude-modulation SLM section of this review. Figure 4a shows the diagram of the LC-SLM based compressive detection optics.…”

“…33 Later, the same group extended the DMD-based binary compressive detection strategy by using two detectors to collect the Raman photons in two different channels. 36 With two detectors, all Raman photons can be collected by using a pair of complementary binary filters that direct photons toward either of the detectors. The optical layout is slightly different from that which uses a single detector, as the two detectors are facing the AE12 position relative to the DMD, respectively.…”

Assessment of Compressive Raman versus Hyperspectral Raman for Microcalcification Chemical Imaging

“…Another approach relies on the fact that acquiring complete vibrational spectra may be inefficient when the information of interest (species proportions or class) is confined in a low dimensional basis. The latter considerations are at the origin of alternative approaches based on compressive Raman technology (CRT) that have recently been proposed (6)(7)(8)(9)(10)(11)(12) for quantification or classification of know species. The idea is to incorporate chemometric analysis directly into the spectrometer hardware.…”