Ophthalmic Optics

• It is the linear distance between point of two consecutive crests.

  Wavelength
• What is the range of the Visible Light?

  380nm to 760nm
• It is known as white light and consists of a collection of component colors.

  Visible Light
• What are the properties of Electromagnetic Waves?

  • Trough
  • Crest
  • Amplitude
  • Wavelength
  • Frequency
• It is lowest point in an electromagnetic wave.

  Trough
• It is the highest point in an electromagnetic wave.

  Crest
• It is the distance between the tip of a crest and the wave's central axis.

  Amplitude
• It is an EM wave property associated with brightness and intensity of the wave.

  Amplitude
• Nanometer was also called millimicrons.
• It refers to the number of full wavelengths that pass by a given point in space.

  Frequency
• Wavelength and Frequency are inversely proportional.
• What are the EM spectrum?

  1. Radiowaves
  2. Microwaves
  3. Infrared
  4. Visible Light
  5. UV
  6. X-rays
  7. Gamma rays
• What is the speed of light in a vacuum?

  299, 792.458 km/s
• What is the speed of light?

  186, 000 m/s or 300M m/s
• It is the smallest unit of light and gives direction to light.

  Ray
• It is the bouncing back of light.

  Reflection
• The surface reflecting the light.

  Reflecting Surface
• The ray of light approaching the reflecting surface.

  Incident Ray
• The imaginary line perpendicular to the refracting surface.

  Normal
• It is the angle formed the incident ray and normal.

  Angle of Incidence
• It is the angle formed by the reflected ray and normal to the surface. 


  Angle of Reflection
• Laws of Reflection: 1) The angle of incidence is equal to the angle of reflection.
• Laws of Reflection: 2) The incident ray and the reflected ray lie on either side of the normal at the point of incidence.
• Laws of Reflection: 3) The incident ray, the reflected ray, the normal at the point of incidence lie in the same plane.
• What are the types of Reflection?

  Regular and Irregular
• It is when a light ray travelling obliquely from one optical medium to another, the light ray deviates (or bends) from its path.

  Refraction
• It is a light ray which is falling on the refracting surface (or interface)

  Incident ray
• It is a deviated ray located on the 2nd optical medium


  Refracted ray
• It is the imaginary line perpendicular to the interface at the point of incidence

  Normal
• It is an angle formed by the incident ray & normal to the surface

  Angle of Inicidence
• It is an angle formed by the refracted ray & normal to the surface

  Angle of Refraction
• It is the ratio of the speed of light in a vacuum (or air) over the speed of light in that medium

  Refractive Index
• The medium that has a lower refractive index

  Rarer Medium
• The medium that has a higher refractive index


  Denser Medium
• It is a homogenous medium which has the same properties in all directions

  Isotropic Medium
• It is an angle between the direction of the incident ray to the direction of the refracted ray

  Angle of Deviation
• It is the angle made by incident ray with a refracting surface or interface

  Glancing Angle
• Law of Refraction: 1)

  The incident ray, the refracted ray, & the normal to the surface all lie in the same plane. The incident ray & refracted ray are on the opposite sides of the interface.
• Law of Refraction: 2) SNELL'S LAW - There exists a constant ratio between the sine of the angle of incidence & the sine of the angle of refraction.
• Law of Refraction: 3) A ray of light passing obliquely from a rarer medium to a denser medium, the light is refracted towards the normal. The speed of light also decreases.