Standoff detection of bacterial spores by field deployable coherent Raman spectroscopy

Area of Science:

• Spectroscopy
• Biotechnology
• Laser Technology

Background:

• Vibrational spectroscopies are crucial for standoff detection of chemical and biological agents.
• Coherent anti-Stokes Raman scattering (CARS) spectroscopy shows promise for detecting bacterial spores via calcium dipicolinate (CaDPA).
• Previous CARS systems relied on bulky, lab-bound laser technology.

Purpose of the Study:

• To develop a compact, rugged, and portable CARS setup for standoff detection.
• To demonstrate the system's capability for sensitive and specific detection of biological threats.
• To overcome the limitations of existing CARS technology for real-world applications.

Main Methods:

• Development of a broadband CARS system utilizing a compact, industrial-grade ytterbium laser.
• Utilizing synchronized pump/Stokes laser pulses to induce molecular vibrations.
• Employing a probe pulse to read the induced coherence and detect emitted signals.

Main Results:

• High signal-to-noise ratio detection of Bacillus atrophaeus spores achieved.
• Detection demonstrated at a concentration of 10^5 cfu/mm^2.
• Successful standoff detection at 1 m with a 1-second acquisition time.

Conclusions:

• The developed CARS system offers chemical specificity and sensitivity.
• The system's ruggedness and portability enable practical, real-world applications.
• This technology advances the development of next-generation instruments for detecting chemical and biological threats.