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Optical diagnostics and imaging techniques have been widely spread in various biomedical and clinical applications. Although these techniques have the advantages of being safe and functional, most of them still suffer from relatively low resolution. The optical scattering and absorption properties strongly affect light penetration in biological tissues. Tissue optical parameters depend on the laser’s wavelength and control light propagation through tissues. However, optical clearing techniques have been proposed to control tissue scattering via equalizing the refractive index through the tissue components using chemicals of high refractive index. Such a procedure can reduce scattering within tissue and increase its optical transparency. Nowadays, tissue optical clearing can be achieved using different scenarios; physical, chemical, photo-chemical/photothermal, and compression, depending on the physical properties of the studied tissue or organ. The IR lasers are utilized in many medical applications, such as photodynamic therapy and bio-stimulation. Additionally, low-intensity infrared lasers cause small heating, leading to tissue water evaporation and increasing optical transmittance. In the present study, tissue optical transmittance has been evaluated after exposure to different IR laser wavelengths. The collimated transmittance of bovine skeletal muscle samples has been monitored using a 650-nm incident laser. The samples have been irradiated with IR lasers at 785 and 980 nm for different periods (A total of 75 min divided into periods of 15 min). The results show that tissue transmittance increased by 27% and 36.7% after irradiation for 75 min with 785 and 980 nm, respectively. Additionally, the optical microscopic images of the 980-nm irradiated samples show higher resolution than native samples.
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