A report on Light, Refractive index and Photodetector

A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.
A ray of light being refracted in a plastic block
A photodetector salvaged from a CD-ROM drive. The photodetector contains three photodiodes, visible in the photo (in center).
The electromagnetic spectrum, with the visible portion highlighted
Refraction of a light ray
A commercial amplified photodetector for use in optics research
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Thomas Young coined the term index of refraction.
Beam of sun light inside the cavity of Rocca ill'Abissu at Fondachelli-Fantina, Sicily
Diamonds have a very high refractive index of 2.417.
Due to refraction, the straw dipped in water appears bent and the ruler scale compressed when viewed from a shallow angle.
A split-ring resonator array arranged to produce a negative index of refraction for microwaves
Hong Kong illuminated by colourful artificial lighting.
In optical mineralogy, thin sections are used to study rocks. The method is based on the distinct refractive indices of different minerals.
Pierre Gassendi.
Light of different colors has slightly different refractive indices in water and therefore shows up at different positions in the rainbow.
Christiaan Huygens.
In a prism, dispersion causes different colors to refract at different angles, splitting white light into a rainbow of colors.
Thomas Young's sketch of a double-slit experiment showing diffraction. Young's experiments supported the theory that light consists of waves.
The variation of refractive index with wavelength for various glasses. The shaded zone indicates the range of visible light.
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The colors of a soap bubble are determined by the optical path length through the thin soap film in a phenomenon called thin-film interference.
Refraction of light at the interface between two media of different refractive indices, with n2 > n1. Since the phase velocity is lower in the second medium (v2 < v1), the angle of refraction θ2 is less than the angle of incidence θ1; that is, the ray in the higher-index medium is closer to the normal.
Total internal reflection can be seen at the air-water boundary.
The power of a magnifying glass is determined by the shape and refractive index of the lens.
The relation between the refractive index and the density of silicate and borosilicate glasses
A calcite crystal laid upon a paper with some letters showing double refraction
Birefringent materials can give rise to colors when placed between crossed polarizers. This is the basis for photoelasticity.
A gradient-index lens with a parabolic variation of refractive index (n) with radial distance (x). The lens focuses light in the same way as a conventional lens.
The principle of many refractometers
A handheld refractometer used to measure the sugar content of fruits
A differential interference contrast microscopy image of yeast cells

In optics, the refractive index ( refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium.

- Refractive index

Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation.

- Photodetector

Polarization: Photons induce changes in polarization states of suitable materials, which may lead to change in index of refraction or other polarization effects.

- Photodetector

where θ1 is the angle between the ray and the surface normal in the first medium, θ2 is the angle between the ray and the surface normal in the second medium and n1 and n2 are the indices of refraction, n = 1 in a vacuum and n > 1 in a transparent substance.

- Light

The illumination measured by a photocell sensor does not necessarily correspond to what is perceived by the human eye and without filters which may be costly, photocells and charge-coupled devices (CCD) tend to respond to some infrared, ultraviolet or both.

- Light

This angle can then be measured either by looking through a telescope, or with a digital photodetector placed in the focal plane of a lens.

- Refractive index
A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.

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