Hologram makes smart spectrometer

Georgia Tech researchers have developed technology to help spectrometers analyse substances using fewer parts, in a wider variety of environments, regardless of lighting.

The researchers say the technology can improve the portability while reducing the size, complexity and cost of many sensing and diagnostics systems that use spectrometers.

Conventional spectrometers have multiple parts: a narrow slit, a lens, a grating, a second lens and a detector. The Georgia Tech team combined these components into two parts: a volume hologram, formed in an inexpensive piece of polymer, and a detector, to create a compact, efficient and inexpensive spectrometer that could be used for multiple spectroscopy and sensing applications. ??

One of the key advantages to the new spectrometer is its insensitivity to alignment. Spectrometers are very sensitive to the direction and wavelength of light and several of their parts are devoted to keeping the light correctly directed. ??The Georgia Tech team was able to incorporate those necessary alignments along with the focusing functions into a volume hologram recorded by the interference pattern of two beams in a piece of photopolymer. ??