Publication Date



Open access

Embargo Period


Degree Type


Degree Name

Master of Science (MS)


Biomedical Engineering (Engineering)

Date of Defense


First Committee Member

Suhrud M. Rajguru

Second Committee Member

Nelson Salas

Third Committee Member

Jorge Bohorquez


The optical properties of a rat muscle and myocardium were measured at two wavelengths 980 and 1860 nm. The tissues used in this experiment were fresh and sliced to a specific thickness of 600 μm. A single integrating sphere system was used to determine the diffuse reflectance, diffuse transmittance, and collimated transmittance of these tissue samples. An inverse Monte Carlo algorithm was then used to calculate the optical properties from the measurements obtained from the single integrating sphere system. The system was calibrated and validated by using distilled water. The absorption coefficient of the rat’s muscles was found to be greater at 1860 nm than at 980 nm. At 980 and 1860 nm, the mean absorption coefficient over 6 samples was 0.182 mm-1 and 1.9785 mm-1 respectively. At 980 and 1860 nm the mean absorption coefficient over 6 samples of the rat’s myocardium was 0.6263 mm-1 and 1.6370 mm-1 respectively. The results showed that there is an increase in absorption in 1860 nm, which follows the general trend of water absorption spectra. Identifying the optical properties is a key step to understanding the mechanism behind photostimulation.


optical properties; 980 nm; 1860 nm; single integrating sphere technique; inverse Monte Carlo