Microscopy (OCR A Level Biology)

Magnification

The number of times larger an object appears compared to the size of the original object.

Resolution

The ability to distinguish 2 points as distinct from one another.

Light Microscopy

Uses focused light and lenses to magnify specimen. Samples are thinly sliced and generally dead. (Max magnification \= x1500 ; Resolution \= 200 nm

Electron Microscopy

Uses beams of electrons to create an image of the specimen. Can be either scanning or transmission.

Transmission Electron Microscope

Uses an electron beam which passes through a thin sample, forming a 2D image. (Max magnification \= x500,000 ; Resolution \= 0.2 nm)

Scanning Electron Microscope

Uses electrons which bounce off of the specimen, scanning its surface and producing a 3D image. (Max magnification \= x500,000 ; Resolution \= 3-10 nm)

Widefield Microscopy

Refers to a basic sample illumination principle. The whole sample is illuminated permanently.

Laser Confocal Microscope

Uses laser light to scan the specimen point by point. These points are then assembled by a computer, forming high resolution images with high contrast.