Maximization of Raman signal in standoff detection under eye-safe conditions

Identification of chemical species using eye-safe laser pulses is becoming of wide interest for both biology and security purposes. Many instruments are designed to this purpose exploiting the high selectivity and sensitivity of the Raman spectroscopy. A laser pulse is sent to a target, and its Raman echo (usually from the Stokes band) is collected by some optics, dispersed and analyzed by a detector. Being the Raman cross sections usually very small, when compliance with the regulations about exposure to laser radiations is requested, each step of the acquisition chain must be optimized in order to lose less photons as possible from the target to the detector. In this work we will discuss some of these aspects with a main focus on the maximization of the laser dose and the detector signal-to-noise.