Active vs. passive tracking: when to illuminate?

Performance benefits of charge-domain gain in active shortwave infrared targeting

“…The metric of interest for sensitivity is generally an SNR or contrast-to-noise ratio (CNR), depending on the imaging task at hand. We have observed in preliminary tracking studies that aimpoint maintenance is more of a target detection problem than recognition or identification, 22 and so CNR is more pertinent to our interests. A general definition for this quantity is 23 CNR=(μtg−μbg)2+σtg2(Fσps)2+(Fσds)2+(σrd/G)2,where μtg, μbg, σtg, σps, σds, and σrd are, respectively, the target signal mean, background signal mean, target signal variation, photon shot noise, dark shot noise, and read noise.…”

“…Empirical evidence from tracking simulations has repeatedly suggested that a minimum CNR of 10 and POT of 50 are sufficient to consistently track without risking a breaklock event 22 . As such, we define a pass/fail figure of merit (FOM) as FOM(CNR,POT)=step(CNR−10)×step(POT−50),where 29 step(w)={1,w>01false/2,w=00,w<0is the Heaviside step function and FOM>0 to maintain a successful track.…”