The reflectance probe was attached to a 640 x 480 pixel micro-SWIR camera (SU640CSX) measuring only 32 x 32 x 28 mm from Sensors Unlimited (Princeton, NJ). Two planoconvex antireflection coated lenses of 60 and 100 mm focal length along with an adjustable aperture were placed between the handpiece and the InGaAs camera to provide a field of view of 11 mm2 at the focus plane. A computer-controlled air nozzle with a 1 mm aperture and an air pressure set to 25 psi was connected to the probe body for dehydration. The handpiece shown in Fig. 2B was held in a clamp with the probe positioned above the occlusal surface of each tooth that was held in a vertical position in a similar configuration that would be used clinically. The efficacy of drying tooth occlusal surfaces with the new probe design was evaluated by measuring the change in intensity in a fixed 25 x 25 pixel area for 6 lesions on 6 teeth, 3 active and 3 arrested after 30 seconds of drying, where ΔIdrying = (I0 - I30)/I0 and I0 and I30 are the intensities at 0 and 30 seconds after applying the air.