High-throughput micro-Raman Aerosol Analyzer

Perceptra proposes a novel swept-source micro-Raman spectrometer for aerosol analysis that reduces the SWaP of traditional systems while significantly improving mechanical robustness and particle analysis throughput.   Raman spectroscopy is one of the most versatile analytical chemistry techniques, proven reliable in applications ranging from industrial process monitoring to security. Nevertheless, the adoption of Raman systems has been limited due to a combination of high cost and low sensitivity of compact systems -- an inherent limitation of traditional systems that rely on dispersive spectrometers with micron-sized slits. Perceptra has developed a novel swept-source Raman spectroscopy architecture that uses a single detector with ultra-high light-gathering power to collect the Raman signal at one wavenumber, while a chip-scale tunable laser scans the entire Raman spectrum across this single channel. By moving the spectroscopy function from a bulky spectrometer to a chip-scale tunable laser, Perceptra has achieved more than 10X reduction in system size. Additionally, replacing the micron-sized slit of a spectrometer with a wide-area detector has improved light-gathering power by 10-100X, allowing for high signal-to-noise ratios even with uncooled detectors. This can reduce the total power consumption of the system by more than 10X, as cooled CCDs are typically the most power-hungry component of the system. Overall Perceptra’s swept-source Raman system offers significant SWaP advantages over traditional dispersive Raman systems.  Micro-Raman systems have recently been proven effective for detecting hazardous compounds in aerosol particles, making them great candidates to provide CBRN and environmental background surveillance data. However, one of the challenges of existing solutions is the small size of the excitation beam (10-50 microns), which requires micro-positioning components for precise alignment to individual particles. This small beam size is necessary to match the input slit of the spectrometer. The alignment requirement not only makes the system bulkier and more power-intensive, but also increases sensitivity to mechanical vibrations, a significant issue for deployment on unmanned systems, especially UAVs. Perceptra’s swept-source Raman spectrometer can easily be converted to a micro-Raman system by using a 2D CCD camera for detection. In this system, every point on the object plane is imaged to a pixel on the CCD, and as the laser wavelength is scanned, every pixel records the Raman spectrum of its corresponding point on the image plane. The wide-area detector enables using larger excitation beams, both eliminating the need for micro-positioning elements and reducing sensitivity to mechanical vibrations. The combination of low SWaP and high mechanical robustness in Perceptra’s swept-source micro-Raman system can significantly enhance the scale at which these systems can be deployed to combat chemical and biological threats.