We have developed Intracavity Laser Refractometry in Reflection (ILRR) method which is perspective for research of liquid biological media. It is based on the control of the laser spectrum. Fast-action and sensitivity of ILRR method correspond to the best results in optical measurements. ILRR method was used for determination of blood refractive index values of healthy and sick persons. The refractive index correlates with the course of the disease. It can serve objective parameter for an estimation of a level of inflammatory processes on organism. We have investigated photoresponse of the blood to low-level laser irradiation. Photoresponse starts just after the turning on red He-Ne therapeutic laser beam. After several dozens milliseconds there is a saturation. At the same time weak thermal effect produces small and slow influence on the refractive index behavior. It can be supposed that fast part of the photoresponse corresponds to the start of biochemical processes. The investigations of photoresponse of plasma leukocytes and erythrocytes showed that the erythrocytes are main photoreceptors of red light on cellular level. Hemoglobin is responsible for the fast photoresponse on molecular level. The refractive index behavior in real time allows to evaluate maximum therapeutic dose on organism, cellular, and molecular levels.
Sergei A. Gonchukov,
Yuri B. Lazarev,
"Intracavity laser refractometry of blood", Proc. SPIE 3599, Optical Diagnostics of Biological Fluids IV, (17 May 1999); doi: 10.1117/12.348367; https://doi.org/10.1117/12.348367