Pictures are very good way of communication. There are some photographs illustrating features of laser light in this article. Photographs were taken using modified camera. High power laser Polaris HP was a source of laser radiation.
Current lasers, used in rehabilitation, are generators from visible to infrared radiation ranges. It appears that the infrared radiation may have varying effects on the human body due to the interaction with tissues and body fluids.
Below are presented several photos taken while infrared radiation.
Fig. 1. Radiation power of 0.8 W, wavelength 808nm, irradiation with a distance of a few centimeters.
Conclusions to Figure 1:
- Radiation illuminated the hand
- This darker areas indicate blood vessels. It can be concluded that the blood strongly absorbs this particular wavelength
- The palm area is more or less evenly irradiated
- It would seem strange that there are no visible bones in the figure. The explanation for that is the dispersion of light in tissue. The tissue disperses the light (a bit like mat glass, through which you can not see clearly)
- The effect of dispersion is not revealed in the case of blood vessels, because the visible vessels were placed just under the skin on the side from which the photo was taken
Fig. 2. Radiation power of 0.8 W, wavelength 808nm, contact irradiation.
Conclusions to Figure 2:
- In relation to the above figure, the conditions have changed due to the contact method of irradiation.
- The picture clearly shows that the hand area, where there is a probe applied from the other side, is brighter
- Contact method results in deeper penetration
Fig. 3. Radiation power of 0.8 W, wavelength 980nm, irradiation with a distance of a few centimeters.
Conclusions to Figure 3:
- Hand has not been illuminated, despite the use of the same power
- According to available data, the wavelength of 980nm is strongly absorbed by water
- 980nm wavelength penetrates much shallower
- Energy absorption by the tissue results in a local increase in temperature (energy absorbed changes its form to the thermal energy)
Fig. 4. Radiation power of 0.8 W, wavelength 980nm, contact irradiation.
Conclusions to Figure 4:
- 980nm radiation, while contact method operation, penetrates deeper than the radiation with a distance of a few centimeters because the veins are visible in the figure.
Fig. 5. Beam shape of the Polaris HP formed in the DILA adapter.
Conclusions to Figure 5:
- A lens system in the DILA adapter causes that within a distance of a few centimeters there is a focus point
- In a glass of water, the focus point is very sharp
- In the human body tissue occurs the strong dispersion. It is clearly visible in Figure 1 where the image of the bones is blurred.
- Dispersion causes that the tissue focus point will be blurred and will have larger size
- Focus in the DILA adapter results in deeper radiation penetration, losses due to passing through the outer layers of tissue are compensated by the increase in energy density as it approaches closer to the focal point
- DILA adapter allows for the effective therapy in the areas located a few centimeters below the skin layer. Using existing laser light sources such therapy treatment was not possible to carry out