CONDENSER CONDENSER LENS LENS AMRITA CHAKRABORTY 02/01/2016 - - PowerPoint PPT Presentation

INSTRUMENTAL TECHNIQUE PRESENTATION

AMRITA CHAKRABORTY 02/01/2016

CONDENSER LENS CONDENSER LENS

• CONDENSER is a lens that serves to concentrate

light from the illumination source in a microscope that is in turn focused through the object and magnifjed by the objective lens.

• WHAT IS IT?
• Used primarily in high effjciency

illumination systems, condensers

• fger

superior aberration correction.

• On

upright microscopes, the condenser is located beneath the stage and serves to gather wavefronts from the microscope light source and concentrate them into a cone of light that illuminates the specimen with uniform intensity over the entire view fjeld.

• Inverted (tissue culture style)

microscopes mount the

• HISTORY
• In the 17th century, the fjrst simple condensers were introduced on pre-achromatic

microscopes (Robert Hooke used a combination of a salt water fjlled globe and a plano-convex lens, and explained its effjciency).

• English makers in the 18th century such as Benjamin Martin, Adams and Jones

understood the advantage of condensing the area of the light source to that of the area of the object on the stage. This was a simple plano-convex or bi-convex lens, or sometimes a combination of lenses.

• By 1837, the use of the achromatic condenser was introduced in France, by Felix

Dujardin, and Chevalier.

• By the late 1840s, English makers such as Ross, Powell and Smith; all could supply

highly corrected condensers (purely empirical) with proper centering and focus.

• Into the late 1870s, in Germany, mainly due to a misunderstanding of the basic
• ptical principles involved, the leading German company, Carl Zeiss in Jena, ofgered

nothing more than a very poor chromatic condenser.

• In 1878, Ernst Abbe produced a very good achromatic design, in order to make

satisfactory photographs of bacteria.

• Optical principles for lenses :

A lens produces its focusing efgect because light travels more slowly in the lens than in the surrounding air, so that refraction, an abrupt bending, of a light beam occurs both where the beam enters the lens and where it emerges from the lens into the air.-- Because

• f

the curvature

• f

the lens surfaces, difgerent rays of an incident light beam are refracted through difgerent angles, so that an entire beam

• f

parallel rays can be caused to converge

• n, or to appear

to diverge from, a single point. This point is called the focal point,

• r

principal focus(F),

• f the lens.

• How does it work?
• Condensers

typically consist

• f

a variable-aperture diaphragm and one or more lenses.

• Light from the illumination source of the

microscope passes through the diaphragm and is focused by the lens(es)

• nto the specimen.
• After passing through the specimen the

light diverges into an inverted cone to fjll the front lens of the objective.

• Condensers with numerical apertures

above 0.95 perform best when a drop of

• il is applied to their upper lens in

contact with the undersurface of the specimen slide. This ensures that oblique light rays emanating from the condenser are not refmected from underneath the slide, but are directed into the specimen.

• Chromatic & Spherical Abberations :

Chromatic aberration : caused by the variation in the refractive index of the lens in the range of light wavelengths Spherical Abberation : caused by the spherical curvature of a lens.

• 1. Depending on imaging modality :
• 1. Bright fjeld : Objective collects only transmitted light.
• 1. Bright fjeld : Objective collects only transmitted light.
• 2. Dark fjeld : Objective collects only scattered light.
• 2. Dark fjeld : Objective collects only scattered light.
• 3. Phase contrast : Phase shifts in light passing through a

transparent specimen is converted to brightness changes in the image.

• 3. Phase contrast : Phase shifts in light passing through a

transparent specimen is converted to brightness changes in the image.

Types of Condenser Lenses :

2.Depending on correction of optical abberation :

• 1. Abbe condenser : simplest, least expensive. Not corrected for

either chromatic or spherical optical aberrations.

• 1. Abbe condenser : simplest, least expensive. Not corrected for

either chromatic or spherical optical aberrations.

• 2. Aplanatic condenser : corrected exclusively for spherical (aplanatic)
• ptical aberrations.
• 2. Aplanatic condenser : corrected exclusively for spherical (aplanatic)
• ptical aberrations.
• 3. Achromatic condenser : corrected exclusively for chromatic

(achromatic) optical aberrations.

• 3. Achromatic condenser : corrected exclusively for chromatic

(achromatic) optical aberrations.

• 4. Aplanatic-achromatic condenser : well corrected for both

chromatic and spherical aberrations and is the condenser of choice for use in critical color imaging with white light.

• 4. Aplanatic-achromatic condenser : well corrected for both

chromatic and spherical aberrations and is the condenser of choice for use in critical color imaging with white light.

• Condenser Lens in Our Lab

Inverted Fluorescence microscope Cytoviva