Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Principles of Geometric Optics Imaging Science Fundamentals

Chester F. Carlson Center for Imaging Science Two Types of Reflection Specular: All the energy coming from one direction will reflect in ONE direction. Diffuse: All the energy coming from one direction will reflect in MANY directions. GLOSSY surfacesMATTE surfaces

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Law of Reflection Law of Reflection 11 22  1 =  2 Incident (incoming) angle = Reflected angle

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Refraction Light slows down in materials. Imagine a line of marching Girl Scouts... Direction of travel

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science “Girl Scouts in the Mud” As the marching line steps into the mud, they will slow down, depending on how thick the mud is. Mud

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Wavefronts at Normal Angle of Incidence

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Index of Refraction u Index of Refraction (n) is the ratio between the speed of light in vacuum (c) and the speed of light in the medium (v). n = c/v MediumIndex of Refraction Vacuum 1 (exactly) Air Water 1.33 Glass 1.5 Diamond 2.4

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science “Girl Scouts in Mud” at an Angle u The direction of travel changes when the marching line hits the mud at a non-normal angle.

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Wavefront at Non-Normal Angle of Incidence

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Snell’s Law u This change in direction is described by Snell’s Law AIR GLASS AIR GLASS normal

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Trigonometry Review  sin(  ) = y/r (opp/hyp)  cos(  ) = x/r (adj/hyp)  tan(  ) = y/x (opp/adj)  Adjacent Side (x) Opposite Side (y) Hypotenuse (r) RULES THAT DEFINE SIN, COS, TAN of an ANGLE:

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Snell’s Law Snell’s Law: n 1 sin  1 = n 2 sin  2 11 22 n1n1 n2n2 (Or, if  1 and  2 are small, n 1  1 = n 2  2 )

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Refraction for Different Materials  AIR WATER GLASS DIAMOND    light

Imaging Science FundamentalsChester F. Carlson Center for Imaging Science Dispersion u Dispersion - Index of refraction, n, depends on the frequency (wavelength) of light. Dispersion is responsible for the colors produced by a prism: red light “bends” less within the prism, while blue light “bends” more.