Estimation of optical pathlength through tissue from direct time of flight measurement," Phys.
Essenpreis, "A monte carlo investigation of optical pathlength in inhomogeneous tissue and its application to near-infrared spectroscopy," Phys.
Explicitly, photometric absorbance measurements from the vascular portions of the image are coupled with an estimation of the optical pathlength using the imaged vascular diameter (and assuming circular vessel cross sections).
Although capillary beds provide a stable optical pathlength, they are sites of active metabolism, so determining total Hgb concentration requires technique tolerances for large variations in oxygen saturation.
The Company's technology is based on Optical Pathlength
Spectroscopy (OPS) and is offered initially in 3F catheter and 1Fr (0.
The optical pathlength (1 mm) was set by stainless steel spacers between the sapphire windows of the optical cell.
This proportionality error is likely attributable to a combination of errors in the concentration of the reference urea solution, variations in the optical pathlength of the sample cell between collection of the pure component spectra and collection of the dialysate sample spectra, and unaccounted for solutes in the sample matrix.
Further, because the etalon is temperature controlled, its optical pathlength
can be modified much more easily than with typical methods of etalon tilt, which require costly active alignment schemes.
Optical pathlength is the only adjustable experimental parameter, which makes it vitally important when designing noninvasive measurement technology.
The regression analysis indicates the effective optical pathlength through water and fat regions of the tissue.
Water or other aqueous reagent is dispensed from the pipettor into microplate wells, and the optical pathlength
in each well is determined in a microplate spectrophotometer.
Intelligent use of two optical pathlengths
within one gas cell gives the system wide dynamic range.