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.