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. ??



Conventional spectrometers work using collimated light (i.e. light moving in only one direction) obtained using a slit and a lens, but this also results in considerable power loss and lower efficiency. The hologram eliminates the need for this hardware.



The Georgia Tech team has a prototype for a lower-end spectrometer comparable to those currently on the market but for a considerably lower cost. Because of its light weight and relative insensitivity to optical alignment, the new design can be used for several applications where portability had been difficult. For instance, the technology would make hand held devices possible for carbon monoxide detection or on-the-spot blood analysis and other biomedical applications.