Image formation with lenses Operating Principle Lenses use
- Slides: 30
Image formation with lenses
Operating Principle • Lenses use the principle of refraction to change the shape of a light beam. - Bending of light – Why?
Operating Principle • Lenses use the principle of refraction to change the shape of a light beam. - Refractive index
Operating Principle • Lenses use the principle of refraction to change the shape of a light beam. - Refractive index
Operating Principle • Lenses use the principle of refraction to change the shape of a light beam. - Refractive index
Operating Principle • Lenses use the principle of refraction to change the shape of a light beam. - Refractive index
Operating Principle
Operating Principle • Lenses use the principle of refraction to change the shape of a light beam. - Refractive index - Curvature
Operating Principle Wavefront picture
Operating Principle Wave picture
Operating Principle • Lenses use the principle of refraction to change the shape of a light beam. - Refractive index - Curvature
Operating Principle • Lenses use the principle of refraction to change the shape of a light beam. - Refractive index - Curvature
Operating Principle • Lenses use the principle of refraction to change the shape of a light beam. - Refractive index - Curvature
Operating Principle Consider lens thickness negligible:
Types of lenses Convex lens:
Types of lenses Concave lens:
Types of lenses Positive meniscus lens:
Types of lenses Negative meniscus lens:
Fresnel lenses
Image formation Ray tracing rules: • In: parallel to the optical axis – Out: through back focal point • In: through the centre of lens – Out: travel unchanged • In: through the focal point – Out: parallel to the optical axis
Image formation Image condition: • “all” light rays emitted by one point in the sample meet in a defined point behind the lens -> imaging plane
Image formation The visualized object: • Each point reflects (emits) light in all directions => multitude of point light sources
Image formation Ray tracing rules:
Image formation Image distance (S 2) in focal dist. Ray tracing rules: Positive lenses Negative lenses Object distance S 1 in focal dist.
Lens systems Compound lenses: • No distance between them (z=0)
Lens systems Compound lenses: • when z > fo+fi - Two converging lenses in series -> upright, scaled image
Lens systems Infinite conjugate system: • if object in the focal point -> the distance between the lenses is not relevant (can be infinite)
Lens systems Infinite conjugate system: • if object in the focal point -> the distance between the lenses is not relevant (can be infinite)
Lens systems Beam expanders: • Collimated light source
Lens systems Beam expanders: • Collimated light source – if expanded. , the light beam is