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

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 Ray tracing rules: Image distance (S2) in focal dist. Object distance S1 in focal dist. Positive lenses Negative lenses

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, the light beam is expanded.