(My) hand transmitting 850nm LED light
This was an experiment to demonstrate the transmission of living tissue in a spectral window between approximately 600 and 1,300nm wavelength. This "window of transparency" is bounded at the long wavelengths side by the harmonics of the stretch and bend vibrations within a water molecule and, at shorter wavelengths below 600nm, by the rapidly increasing absorption of blood and, basically, most living tissue including plants.
With the exception of some X-rays and km-length radio waves, this is the only spectral band where light can penetrate deep into components of the biosphere. From a growing number of experimental investigations, it is becoming apparent that light at these wavelengths — coming mostly from the Sun — plays essential roles in maintaining the health of most life on the planet Earth (including us!)
For close to 3.5 billion years, life on Earth has evolved to exploit light from the Sun to power itself, either directly (cyanobacteria and plants) or by stored food and fossil fuels generated by photosynthesis.
Only in the last few decades have energy-efficient sources of artificial light appeared that produce copious visible light but little or no far-red or near-infrared light within this transparency window. These lights, especially the ubiquitous white LEDs, have broken these billions of years of adaptation of life to 'thermal' light sources (light produced as a result of the hight temperature of the emitter) which are rich in near-infrared light.
Living, as many of us do, under these white LEDs for large fractions of our lives without exposure to sunlight has starved us of this near-infrared light that can penetrate our bodies. This is needed to protect us from such afflictions as type 2 diabetes, obesity and a number of 'diseases of ageing' which result from the diminishing ability of the mitochondria (the energy generators in cells) to produce enough energy as we age.
The image above was obtained using a 'full-spectrum' adapted Sony alpha camera with a filter that passes light above about 750nm. The light source, behind a hand-shaped alu-foil covered cardboard mask, was a "Candeer 54W Red Light Therapy" LED lamp that has diodes emitting 660 and 850nm light. Only the longer wavelength LEDs pass through the filter to produce this image which is the combination of three exposures each separated by 2.5 stops and combined using Photomatix Pro software to result in the high dynamic range.
De-oxygenated haemoglobin has a spectral absorption band around 750nm which results in the veins (but not arteries) being seen as dark in this image. The image shows that this long wavelength light can penetrate deep into our bodies where it appears to perform a number of beneficial functions.
It has been estimated that around 60% of cells in non-obese human bodies are reached by this light where it appears to enhance the efficiency of metabolism by oxidative respiration and produce cellular energy for immediate use before diverting metabolised food to storage as fat.
[Note: bones are relatively transparent to 850nm light, resulting in this looking quite different to an X-ray image of the hand.]
(My) hand transmitting 850nm LED light
This was an experiment to demonstrate the transmission of living tissue in a spectral window between approximately 600 and 1,300nm wavelength. This "window of transparency" is bounded at the long wavelengths side by the harmonics of the stretch and bend vibrations within a water molecule and, at shorter wavelengths below 600nm, by the rapidly increasing absorption of blood and, basically, most living tissue including plants.
With the exception of some X-rays and km-length radio waves, this is the only spectral band where light can penetrate deep into components of the biosphere. From a growing number of experimental investigations, it is becoming apparent that light at these wavelengths — coming mostly from the Sun — plays essential roles in maintaining the health of most life on the planet Earth (including us!)
For close to 3.5 billion years, life on Earth has evolved to exploit light from the Sun to power itself, either directly (cyanobacteria and plants) or by stored food and fossil fuels generated by photosynthesis.
Only in the last few decades have energy-efficient sources of artificial light appeared that produce copious visible light but little or no far-red or near-infrared light within this transparency window. These lights, especially the ubiquitous white LEDs, have broken these billions of years of adaptation of life to 'thermal' light sources (light produced as a result of the hight temperature of the emitter) which are rich in near-infrared light.
Living, as many of us do, under these white LEDs for large fractions of our lives without exposure to sunlight has starved us of this near-infrared light that can penetrate our bodies. This is needed to protect us from such afflictions as type 2 diabetes, obesity and a number of 'diseases of ageing' which result from the diminishing ability of the mitochondria (the energy generators in cells) to produce enough energy as we age.
The image above was obtained using a 'full-spectrum' adapted Sony alpha camera with a filter that passes light above about 750nm. The light source, behind a hand-shaped alu-foil covered cardboard mask, was a "Candeer 54W Red Light Therapy" LED lamp that has diodes emitting 660 and 850nm light. Only the longer wavelength LEDs pass through the filter to produce this image which is the combination of three exposures each separated by 2.5 stops and combined using Photomatix Pro software to result in the high dynamic range.
De-oxygenated haemoglobin has a spectral absorption band around 750nm which results in the veins (but not arteries) being seen as dark in this image. The image shows that this long wavelength light can penetrate deep into our bodies where it appears to perform a number of beneficial functions.
It has been estimated that around 60% of cells in non-obese human bodies are reached by this light where it appears to enhance the efficiency of metabolism by oxidative respiration and produce cellular energy for immediate use before diverting metabolised food to storage as fat.
[Note: bones are relatively transparent to 850nm light, resulting in this looking quite different to an X-ray image of the hand.]