Distance-Resolving Raman Radar Based on a Time-Correlated CMOS Single-Photon Avalanche Diode Line Sensor

Area of Science:

• Spectroscopy
• Photonics
• Sensor Technology

Background:

• Remote Raman spectroscopy faces challenges with background radiation from ambient light and sample fluorescence.
• Existing methods struggle to simultaneously acquire spectral data and target location while mitigating noise.

Purpose of the Study:

• To introduce the first distance-resolving Raman radar system.
• To demonstrate background suppression and simultaneous distance measurement capabilities.

Main Methods:

• Utilized an adjustable, time-correlated complementary metal-oxide-semiconductor (CMOS) single-photon avalanche diode line sensor.
• Employed sub-nanosecond time gating for background noise suppression.
• Verified distance resolution and spectral identification of samples at various distances and background light intensities.

Main Results:

• Achieved a distance resolution of 3.75 cm.
• Successfully distinguished Raman spectra of titanium dioxide at 250 cm (250 lux background) and 100 cm (7600 lux background).
• Identified major Raman peaks of olive oil (fluorescence-to-Raman ratio 33, fluorescence lifetime 2.5 ns) at 30 cm with 250 lux background illumination.

Conclusions:

• The developed time-correlated CMOS single-photon avalanche diode sensor enables compact, distance-resolving Raman radars.
• This technology offers simultaneous spectral analysis and distance information for applications within several meters.
• Potential for new compact Raman radar systems in diverse fields requiring remote sensing.