Breckland Scientific 2023 Catalogue

Microscopes

Microscope Glossary

a

GLOSSARY Term

b

Meaning

Achromatic Lens

A lens which is colour corrected, typically for red and blue light. This limits achromatic aberrations.

c

Binocular

A microscope with two eyepieces, the light path is split and the same image is seen by each eye.

Condenser

A lens or assembly of lenses which focus light through the specimen.

Compound Microscope

Also known as upright or biological microscopes these have two lens systems (objective and ocular) and are used when a high magnification is needed. Binocular, compound microscopes do not give a three-dimensional image. Regulates the amount of light on the specimen either by means of a rotating disc under the stage (disc diaphragm) or an adjust- able multi-leaf aperture (iris diaphragm).

d

Diaphragm

e

DIN An optical standard that defines the tube length and thread of objective lenses. This allows DIN objectives to be interchangeable between microscopes made by different manufacturers. Diopter Adjustment Needed for binocular microscopes to compensate for differences between the eyes of the user. Allows the focus of each eyepiece to be slightly different. Eyepiece Contains the ocular lens or lenses which re-magnify the image formed by the objective lens. Wide Field (WF) eyepieces give a wide, fairly flat field of view.

f

g

Eyepiece Micrometer (graticule or reticule)

A scale inserted into the eyepiece to allow, once calibrated, direct measurements of a specimen. (See page 293)

h

Field of View (FOV) The area of the specimen seen in the image formed by the microscope. Focusing Mechanism Changes the distance between the objective lens and the specimen in order to focus the image. Illumination

i

Transmitted light passes through the diaphragm, specimen and lenses. Incident light falls onto the specimen and then through the lenses. This can be from an external source eg natural light, either with or without use of a mirror, or from an inbuilt light source. Most modern educational microscopes use LED light sources though tungsten and halogen illumination is still common.

j

Mechanical Stage

Allows the specimen to be moved in x and y directions without touching the slide.

Monocular A microscope with a single eyepiece for use with one eye. Nosepiece (or Turret) Holds objective lenses and is rotated to change magnification. Numerical Aperture (NA)

k

A measure of the ability of a lens to gather light and resolve fine detail. The NA of an objective lens should be lower or equal to the NA of the condenser with which it is being used. These are the primary lenses that magnify the specimen. Most objectives are labelled to show their power (magnification) and their NA. Other information may include the recommended thickness of cover slip, the working distance and the lens type.

l

Objectives

m

Parcentered

Almost all microscopes are parcentered i.e. the image remains centred when changing objective.

Parfocal

A microscope with parfocal objectives should require little re-focusing when changing magnification as the objectives all focus in the same plane.

n

Phase Contrast

A method used to enhance the image of a colourless or transparent specimen.

Semi-Plan (SP)

A lens which is flatter than a standard lens hence a greater proportion of the image is in sharp focus.

o

Siedentopf

A type of binocular head where the inter-pupillary distance is altered by moving the eyepieces in a circular motion rather than slid- ing them together and apart. This removes the need to re-focus once the adjustment is made.

Stage Micrometer A slide with a scale for calibrating eyepiece micrometers (graticules or reticules). Stereo Microscope Unlike a binocular compound microscope, a stereo microscope produces a three-dimensional image as each eye sees the image through a different optical path. Stereo microscopes are used to look at specimens under low magnification. Trinocular A microscope with two eyepieces and a port for a camera/video. The light path is split and the same image is seen by both eyes and by any camera/video attached to the trinocular port.

p

q

r

All 3 frog blood images were taken using an Optika microscope

s

t

v

Frog Blood using 100x objective in air

Frog Blood using 100x objective in oil

Frog Blood using 100x objective in water

w

304

Value | Service | Expertise