Stacked, Mutually Rotated Diffraction Gratings as Enablers of Portable Visible Spectrometry

Abstract

Two-dimensional color CMOS cameras have become ubiquitous. They promise to support ubiquitous spectrometry. When raw illumination levels can be measured by such cameras, their use for spectrometry depends on using as many pixels as possible and on being able to calibrate images at point-of-use. Stacked, mutually rotated transmission diffraction gratings provide a means to generate multi-order, wide dynamic range dispersed visible spectra suitable for absorption, reflection, and fluorescence spectrometry. The theoretical basis for dispersion, resolution, and normalization of such spectra are derived, and initial characterization is reported.

Portable Spectroscopy

“…Form an optical point of view, the availability of the very compact wavelength-selective devices described above (transmission gratings, scanning Fabry-Perot filters, MEMS scanning gratings, linear variable filters, mosaic filters, discrete filters, all possibly mounted in 3D-printed housings 497 ) enable very compact additions to the smartphone for low-resolution, colorimetric spectroscopy; the use of low-cost stacked transmission gratings has been investigated by Scheeline et al to gain higher resolution and improved dynamic range. 498,499 One fascinating integrated smartphone spectropolarimeter was developed for ''citizen science'' observations of atmospheric aerosols, 500 where 3187 people made simultaneous measurements that were compared to standard field instrumentation. A paper has described interfacing a miniature spatial heterodyne Raman spectrometer with a cell phone camera.…”

“…to gain higher resolution and improved dynamic range. 498,499 One fascinating integrated smartphone spectropolarimeter was developed for “citizen science” observations of atmospheric aerosols, 500 where 3187 people made simultaneous measurements that were compared to standard field instrumentation. A paper has described interfacing a miniature spatial heterodyne Raman spectrometer with a cell phone camera.…”

How to Design a Spectrometer

“…My graduate advisor, Professor John P. Walters, who had designed (or worked with others to design) several generations of spatio-temporally resolving optical spectrometers, [1][2][3][4][5][6] once advised me, ''Never build your own spectrometer.'' Now that I and my collaborators have designed and built several spectrometers 7,8 and related optical systems, [9][10][11][12] I recommend to the reader: Never build your own spectrometer-unless doing so is the only way to solve a problem that you care about! But how can one know if the right instrument is already available from a vendor?…”

A Review of Portable High-Performance Liquid Chromatography: the Future of the Field?

“…A considerable number of research articles and reviews have directed their attention to the potential of developing mobile and handheld devices based on various detection methods. Some of these include Raman [82][83][84][85][86][87], ultraviolet (UV) [88], visible [89], ultraviolet-visible (UV-vis) [90][91][92], near-infrared (NIR) [93,94], Fourier-transform infrared spectroscopy (FTIR) [95,96], induced fluorescence [97][98][99], electrochemical detectors (ECDs), and X-ray fluorescence [100][101][102]. The vast majority of these methods can be adapted to detect and quantify eluting analytes in an LC instrument.…”