An analog Mueller matrix data acquisition system (AMMS) acquiring middle-infrared Mueller (M) matrices of backscattering surfaces. The M-elements are measured by means of an active photopolarimetric sensor. The AMMS records nine M-elements simultaneously in groups of four modulo 2 incident continuous-wave CO.sub.2 laser beams--one incident beam is tuned to a fundamental molecular absorption cross-section by the aerosol of detection interest (analytic wavelength .lamda..sub.a) while the other beam is detuned off that resonance band (reference wavelength .lamda..sub.r) and in the closest vicinity to .lamda..sub.a. Accordingly, those .DELTA.M elements exhibiting susceptible behavior to the aerosol analyte, driven on-then-off its molecular vibrational resonance band, cues an identification event thus providing detection decision information. The AMMS is comprised of PEM reference frequency synthesizer, optical power regulation, data digitizer, and computer interface components in an interfaced and integrated framework that governs all operations of M-elements production by the photopolarimetric sensor.