Extending Human Vision to Infrared and Ultraviolet Light: A Study Using Micro-Particles and Fluorescent Molecules

Abstract

In this study, rare earth doped infrared (IR) to visible, up-converting particles along-with efficient ultraviolet (UV) to visible fluorescent molecules were imbedded in proteins and were used as a mean for increasing the human vision range to infrared and ultraviolet wavelengths. Stilbene-420 fluorescent molecules which convert near UV light to blue light, were chosen for the strong overlap of their fluorescence emission with the sensitivity region of blue cone cells and for the ability of blue light to increase the regeneration of bleached visual pigments. Our data show that the up-conversion efficiency of the IR up-converting particles and blue fluorescing molecules efficiencies remained unchanged when these material are imbedded in proteins compared to their efficiencies in water solutions. Addition of up-converting particles to rod visual cells resulted in the bleaching of the visual pigments, rods, when irradiated with infrared light (980 nm) whereas no bleaching was observed, under the same conditions, without the presence of up-converting particles. This suggests that the up-converted green light induced visual process in the rod visual pigments. In addition, we describe the design and present data of a novel optical device, which can be used as eye glasses, utilizing up-converting particles that allows the wearer to see rather intense infrared light.INDEX TERMS Extended spectral vision, green fluorescent protein, rare earth doped upconverting particles.

Enhancing the upconversion efficiency of NaYF4:Yb,Er microparticles for infrared vision applications

“…Our data also show that as the concentration of the UCPs [NaYF 4 :Yb,Er] increases in the dispersion medium, the intensity of the upconverted light, as expected, increases linearly 35 . To increase the intensity of the upconverted green light, while the pumping intensity at 980 nm remains the same, we attached 980 nm reflecting mirrors on the sides of the cuvette that contains the upconverting microparticles.…”

“…In our earlier studies, we have shown that these upconverting particles can be utilized to induce infrared vision in humans by converting bright infrared light to visible light 35 . Moreover, it has been shown that the injection of rare-earth-doped upconversion nanoparticles into the eyes of mice enables them to see in the near-infrared light 36 .…”

“…Moreover, it has been shown that the injection of rare-earth-doped upconversion nanoparticles into the eyes of mice enables them to see in the near-infrared light 36 . However, one major limitation regarding such uses of UCPs is that their upconversion quantum yield is typically less than 1% at room temperature 37 , 38 , due to the small excitation cross-section of the lanthanide doped materials (e.g., Nd 3+ , Ho 3+ , Er 3+ , Tm 3+ , Yb 3+ ) 34 , 35 , 38 . Therefore, enhancing the upconversion luminescence efficiency is one of the major challenges encountered in this field.…”

“…The crystal structure of the upconverting particles is known to have a strong influence on the upconversion efficiency. To that effect, it has been shown that hexagonal β NaYF 4 crystals, activated by Yb 3+ and Er 3+ , are an order of magnitude more efficient than α NaYF 4 crystals 35 , 44 , 45 .…”

Light-Eye Interaction Physics Review

“…Light comes after air and water in terms of abundance in nature, and it has an important role in the growth and continuation of life. The optical spectrum, which is visible to the human eye, is a narrow part of the electromagnetic spectrum in the wavelength range from 400 to 760 nm [1][2][3]. As an electromagnetic radiation, light exhibits characteristics of both waves and particles (photons) and propagates in a vacuum at the speed of light (𝑐).…”