In Physics, a prism is defined as a transparent, polished flat optical element on which light reflects. In a prism, one surface must be angled because objects with two parallel polished surfaces are not considered as prisms. Prisms are made up of materials that are transparent to the wavelengths for which they are designed. The materials generally used to make a prism are glass, plastic, and fluorite. The traditional shape of a prism is somewhat triangular.
Types of Prism:
Dispersive Prisms - Dispersive prisms are used for breaking up the light into its constituent colours because the refractive index is dependent on the frequency. The white light that enters into this prism is a mixture of various wavelengths and frequencies. After passing through the prism, each light frequency bent in a different direction. Some examples of dispersive prisms are Triangular prism, Abbe prism, Pellin-Broca prism, Amici prism, Compound prism, and Grism.
Reflective Prisms - Reflective prisms are used for reflecting light. To flip, invert, rotate, deviate or displace the light beam, a reflective prism is used. This type of prisms is used in binoculars or single-lens reflex cameras for the purpose of getting an erect image. If it is not used in these devices, then the image will be upside down for the users. Some common examples of reflective prisms are Porro prism, Porro-Abbe prism, Amici roof prism, Pentaprism, Abbe-Koenig prism, Schmidt-Pechan prism, Bauernfeind prism, Dove prism, and Retroreflector.
Polarizing Prisms - Polarizing prisms are used for splitting a beam of light into components of varying polarization. Polarizing prisms are made up of materials that are known as birefringent crystalline. Some common examples of the polarizing prism are Nicol prism, Wollaston prism, Nomarski prism, Rochon prism, Senarmont prism, Glan-Foucault prism, Glan-Taylor prism, and Glan-Thompson prism.
Deflecting Prisms - Deflecting prisms are used for deflecting the beam of light at a fixed angle. Beam steering can be done by using a pair of these prisms. On rotating the prisms, the beam gets deflected into any desired angle within the limit if a conical “Field of Regards”. Some examples of deflecting prisms are Rhomboid prism and Deck prisms.
Beam-Splitting Prisms - Prisms that are used to splitting a single beam into two or more beams are known as beam-splitting beams. Some of the common examples of this prism are Beam splitter cube and Dichroic prism.
Derive the Prism Formula
∠ALO + ∠AMO = 2rl∠s
(From Quadrilateral and ㄥALO = ㄥAMO = 90°)
ㄥLAM + ㄥLOM = 2rt ∠s (sum of four ∠s of a quadrilateral = 4rt ∠s) (Eq.2)
∠r1 + ∠r2 + ㄥLOM = 2rt ∠s (Eq.3)
ㄥLAM =∠r1 + ∠r2 ( Comparing Eq.2 and Eq.3)
A = ∠r1 + ∠r2
δ = i1 + i2 − A ( Substituting A in Eq.1)
i1 + i2 = A + δ∠i1 = ∠i2
∠r1 = ∠r2 =∠r
ㄥALM = ㄥLMA = 90° - ∠r
Thus, AL = LM and LM॥ BC
ㄥA =∠r1 + ∠r2
A = 2r ( Since, ∠r1 = ∠r2 =∠r)
