Optical surface metrology in 3D for small animal non-contact diffuse optical tomography

Abstract

We present an optical metrology system for measuring the outer shape of small animals in 3D using a stereo camera pair. This system will be integrated into a non-contact small animal diffuse optical tomography (DOT) scanner we are currently developing. The key feature of our approach is to use the same laser beam as that for the tomographic measurements, thus considerably reducing system complexity. Moreover, the 3D data are acquired simultaneously with the DOT measurements. Precise measurements (< 1 mm) are achieved via a novel axis (rotational and translational) optical calibration technique allowing the acquisition of full 3D models. Our approach allows to measure, rather than indirectly infer, the exact position where laser light is injected into the animal, in contrast to other approaches. This is extremely useful information for the tomographic reconstruction algorithm. 3D measurements of a reference shape and of a small animal are presented, showing the precision and effectiveness of our system.