Illumination and Resolution in Microscopy

This collection of flashcards covers key vocabulary and concepts related to illumination and resolution in microscopy, including Köhler illumination, aberrations, resolution limits, and optical principles.

Köhler illumination

An illumination technique that provides controllable and homogeneous lighting for samples, developed in 1893.

Critical illumination

A lighting method that can cause issues such as non-homogeneity and excessive intensity.

Conjugate planes

Two planes in an optical system where one contains the image of the points defining the other.

Resolution

The minimum distance between two features that a microscope can differentiate.

Aberrations

Errors that occur in optics that lead to distorted or blurred images.

Airy pattern

A diffraction pattern that represents the minimum point of light that can be sustained by a circular aperture.

Rayleigh criterion

The theoretical limit of resolution for optical systems based on diffraction.

Objective

The optical component of a microscope that gathers light from the sample to form an image.

Collector lens

A lens used to gather light from a light source and focus it onto the sample.

Diaphragm

An adjustable opening that controls the intensity and size of the light source in illumination.

Field of view diaphragm

A diaphragm that defines the area visible in the image plane of the microscope.

Sparrow’s resolution limit

A practical limit of resolution based on the separation of objects that can still be seen distinctly.

Working distance

The distance between the objective lens and the nearest surface of the sample.

Depth of field

The range of distance within which the object appears in focus.

Optical aberrations

Deficiencies in lens systems that prevent them from forming perfect images.

Defocus

A phenomenon where the detector is not positioned in the focal plane, leading to blurred images.

Decenter

An error where the optical element is not aligned with the optical axis.

Tilt

An error arising when an optical element is not perpendicular to the optical axis.

Longitudinal chromatic aberration

A type of chromatic aberration where different colors focus at different points.

Lateral chromatic aberration

A type of chromatic aberration where different colors are imaged at different heights.

Spherical aberration

Variation of focus with aperture; results in a circle of least confusion.

Coma

Aberration that causes a point source to appear comet-like, with tails.

Field curvature

A distortion where the image plane is not flat, causing focus issues.

Distortion

A failure in magnifying the image uniformly across the field of view.

Astigmatism

An aberration where points off-axis have different focal points due to lens asymmetry.

Abbé criterion

A formula that gives the resolution limit based on the numerical apertures of the objective and condenser.

Numerical Aperture (NA)

A dimensionless number that characterizes the range of angles over which the system can accept or emit light.

Condenser

A lens system that focuses light onto the specimen.

Immersion lens

A lens designed for use with immersion liquids to increase resolution.

Field number

The diameter of the field of view in microscopy, measured in mm.

Photographic purposes

Applications of microscopy used to capture and document images.

Optical system

The assembly of lenses and other components that form an optical device.

Light source

The source of illumination used in microscopy, such as a lamp or LED.

Image plane

The plane where the image is focused and captured in a microscope.

Eyelens

Part of the optical system that magnifies the image for the observer.

Tube lens

The lens that connects the objective and eyepiece in a microscope.

Virtual light source

An apparent source of light created by an optical system.

Homogeneous illumination

Uniform light distribution over the sample in microscopy.

Physical light source

An actual light source used in illumination systems.

Parallel rays of light

Light that travels in straight lines and does not converge or diverge.

Image of the diaphragm

The visual representation of the diaphragm at the sample plane.

Sample illumination

The method used to light the sample for observation in microscopy.