Spectrophotometry of hemoglobin in microvessels is commonly performed by collecting light
either from a small region around the vessel centerline or from the entire lumen of the
vessel. In the latter instance, parallel rays of light may not encounter the same amount of
absorbing species. Hence, a phenomenon similar to the sieve effect reported in the literature
on hemoglobin spectrophotometry may be expected to occur. Although it has been observed
that under such circumstances nonlinearities in calibration characteristics arise, the …