Aberration - an optical
defect in the design of a lens. The lens does not bring all the rays of
light to an exact focus. There are several different types of
aberrations each having a contributing factor on image quality.
Achromat - A lens system that has been designed
to reduce chromatic aberration. A photographic lens system is usually
corrected to provide the same focal length for the red and blue
Achromatic - color-corrected optics used to
produce true specimen color.
Achromatic Condenser - a condenser corrected
for both spherical aberration. It is the most common type found on
bright field microscopes.
Alignment - condition in which all optical
elements are centered on the same axis.
Aperture - a fixed or adjustable opening or
hole through which light may pass. Located beneath the microscope stage.
Apochromat - A lens system in which chromatic
aberration is corrected for three or more colors. Apochromatic lenses
are used in photoengraving applications and for telephoto lenses that
have large maximum apertures.
Arm - part that serves as both the support of
the body tube and its lens systems and as the held part of the
microscope when it is carried.
Base - the weighted bottom of the microscope
which gives it both good balance and resistance to unexpected movement ,
Body Tube - the main structure which holds the
eyepiece and objectives at a precise distance to each other, and which
allows this combined system to approach the stage into clear focus.
Brightfield - used to examine
specimens which have contrast/color (i.e. stained histological
- a brightfield condenser and brightfield objectives.
- cannot be used to view specimens of little or no contrast.
Brightfield Illumination - the ray of
light incident upon the object is parallel to the optical axis.
CCD-Charged Coupled Device.
This is the image detector in a video camera.
Chromatic Aberration - an optical defect of a
lens, seen as color fringes or halos, which causes different wavelengths
of light to be focused at different distances from the lens.
Coarse Adjustment - the knob which moves the
specimen (or objective) rapidly, vertically for focusing.
Color Balance - a method of correcting a light
source by way of filtration so that the light has optical
characteristics similar to sun light.
Color Temperature - the quantitative value
indicating the amount of color or colors emitted by an object.
Condenser - the lens system between the
illuminator and the specimen which condenses the light and focuses on
Confocal - an interferometric microscope
utilizing a rotating aperture and a CCD image analysis.
Contrast - light and dark. To produce a good
image, you must have good contrast as well as good resolving power
Corrected Lens - a lens or lens system which
corrects for specific aberrations.
- used to examine specimens which cannot be distinguished from the
background; (i.e. syphilitic spirochetes, silver grains in
- a dry darkfield condenser for low magnifications and any low
magnification objectives. An oil darkfield condenser for higher
magnifications. High magnification oil objectives must have an iris.
- the ray of light incident upon the object is at an angel from the
optical axis; therefore scratches and dents on the surface are
illuminated while the other intact part remains dark.
Daylight Filter - a blue filter used to correct
the color temperature of a light source.
Depth of Focus - range around the
focal point in which the image is still clear. The larger the
N.A., the smaller the depth of focus.
Contrast - (Often called Nomarski)-used to
examine round, multi-cellular, tubular or thick transparent specimens.
- DIC condenser, re-combination prism, DIC objectives.
specialized item and usually ordered for specific applications.
- price; cannot be used with plastic dishes.
DIN - Deutch Industrie Norm-international
standard used in the manufacture of interchangeable objective lenses. A
typical DIN type microscope utilizes 45mm objectives+160mm tube length
for a 205mm system length.
Diaphragm - a rotary disk, located under the
stage, whose graded opening allows a variety of angles of light to come
up through the stage opening. Also available as a continuously varying
diameter adjusted by a lever located on the side of the component.
Drawing Tube (Camera Lucida) - enables a person
to view the specimen and the paper/pencil simultaneously for drawing.
Dual Viewing Attachment - enables two people to
view the same specimen through the same microscope simultaneously.
Empty Magnification - magnification which
increases the size, but does not increase the detail, due to the
limitation of the resolving power of the optical system.
Eyepiece - the lens system closest to the eye.
Magnifies the image produced by the objective. So, with a 10X objective
and 10X eyepiece, the total magnification is 100X.
Eyepiece tube - a smaller diameter extension of
the body tube which receives the eyepiece.
Eye Point - the location of the eye when using
a visual instrument which allows for the best possible viewing.
Eye relief - the distance from the eye lens of
the microscope to the eye point.
Fluorescence - use to locate
fluorescently tagged material (protein, enzyme, gene) by illuminating
the material with one wavelength of light in hopes that the fluorescence
tag will appear by emitting this light at a different wavelength; i.e.
FITC labeled materials in tissue when illuminated with blue light will
emit with green light.
- Epi fluorescence attachment, a mercury (or other) light source, power
supply, specialized filter systems, each one for a different fluorescent
- Specimen is usually fragile, unstable and cannot be used for long
periods or stored.
Fluorite - an objective
corrected for two wavelengths and therefore, with a higher resolving
power than an Achromat. (There are exceptions) Manufacturers call them
Fluor, Neo-Fluor, Fluotar.
Field - the actual diameter of the viewing
area, usually expressed in millimeters. As magnifying power is
increased, the field of view is decreased.
Filter - a colored transparent material placed
in the path of illumination to vary the conditions of viewing.
Filter mount - an existing slot on the
microscope which can hold one of a set of filters in the path of
Fine Adjustment - the knob which moves the
specimen (or objective) slowly, vertically for focusing.
Finity Correction System - an optical
system in which the image is formed only by an objective lens.
Focal Length - distance between a
principal point and a focal point. f1 is a focal length of
objective, f2 is a focal length of tube lens. Magnification is
determined by the ratio of objective lens focal length and tube lens
focal length. (for Infinity correction system)
Focus Rack - part of the assembly (plus pinion)
which specifically allows the distance from the objective lens to the
specimen to vary, and therefore permit required coarse and fine focus
Fully (Anti-reflective) Coated - coating of a
lens which improves its ability to transmit light more efficiently.
Hoffman Modulation Contrast
- called the "poor man's" Nomarski. Used to examine the same
types of specimens as DIC/Nomarski.
- Hoffman condenser, polarizer and Hoffman objectives.
Loss of some resolving power.
Huygenian Eyepiece - an eyepiece which effects
a certain amount of correction for chromatic difference of magnification
in the achromatic objective lens.
Illuminating Mirror - usually a two-sided
mirror on a rotating axis located below the stage. It reflects light up
into the stage opening and onto the specimen.
Illumination - the supply of light onto the
object under the objective lens.
Illuminator - the source
of light which illuminates the object or specimen to be observed. May be
fixed intensity, or variable.
Image Plane - a plane which is at right angles
to the optical axis at the image point.
Inclination Joint - located at the base of the
arm of some microscopes allowing the viewer to tilt the microscope at a
more comfortable angle to look at dry slides.
Incline(30-45 degrees) - the eyepiece tube is
manufactured at an angle to the horizontal to allow more comfortable
posture during long periods of observation.
Infinity Correction System - an
optical system in which the image is formed by an objective lens and a
Interchangeable Eyepiece - a lens system which
fits within the eyepiece tube and which is usually replaced by another
lens of equal mounting diameter but of different magnification power.
Interchangeable Objective - a lens system
threaded into the nosepiece turret which can be removed and which is
usually replaced by another lens of equal mounting diameter and
threading, but different magnification power.
JIS Standard-Japanese Industrial Standard
-international standard used in the manufacture of interchangeable
objective lenses. A Typical JIS type microscope utilizes 36mm
objectives+170mm tube length for a 206mm system.
Lens - optical glass which has two polished
surfaces and is used to converge or diverge light rays.
Light - electromagnetic radiation.
Long Working Distance -
usually an objective with a greater than normal working distance.
micro-manipulation, inverted microscopy, producing micro
instruments. A normal 40X objective will have a working distance of
0.06mm. A long working distance 40X will have 2.4mm; an extra long
working distance 40X will have 10mm; a super long working distance 40X
will have 15mm. The longer the working distance, the lower the resolving
Magnification - an enlargement of an object by
an optical instrument. It is the ratio of the size of the image to the
actual size of the object under observation.
Magnifying Power - a
measure of the ability of a lens or combination of lenses to make an
object appear larger. It is the number of times the image seen through
the microscope is larger than the object would appear to the unaided
Micro-manipulator - used to inject or extract
substances from the specimen. Also used to measure electric current
produced by the specimen.
Microscope - a high precision optical
instrument which uses light to observe objects. It is capable of high
magnification and resolution and is used for making minute details
Motorized Scanning Stages - used to allow a
computer to control movement of the specimen. Highly specialized and
rare at the moment but soon will become the "in" thing in
combination with CCTV.
Multi-viewing Attachment - enables 2-8 people
to view the same specimen through the same microscope simultaneously.
N.A. - Numerical Aperture. N.A
determines resolving power, focal depth, and luminosity of the image.
The larger N.A., is, the higher resolving power and smaller focal depth
Nosepiece - a rotary turret mounting for the
set of objectives.
Numerical Aperture (N.A.) - a number to
represent resolving power of an objective.
Objective Lens - the compound lens system in a
microscope which receives light from the field of view and forms the
first image. The lens system closest to the specimen. Produces the
primary magnification; i.e. 2X, 4X, 10X.
Ocular Micrometer - inserted in the eyepiece,
it enables the person to measure the specimen.
Oil Immersion - a technique of placing special
oil between positioned 100X objective and the glass slide on the stage
to improve the resolving quality at high magnification. Also placed
between the condenser and the glass slide.
Parallax - an imaging error introduced when
using a stage micrometer of significant thickness. This is when the
scale and the specimen appear to be in the same plane, thus causing
Parfocal - the ability to rotate the objective
turret with minimal refocusing.
Parfocal Length - distance between
the surface of the specimen and objective lens mounting position when in
- used to examine live, unstained specimens.
- Phase condenser and phase objectives.
produces an optical artifact called the phase halo. It is, therefore,
completely unusable for round, multi-cellular or tubular specimens. i.e. eggs, worms (nematodes), neurons.]
- Can only be attached to a trinocular tube.
clear focus, minimum to no vibration and great flexibility in
interchangeability of film holders; i.e.-35mm. Polaroid 3 x 4 or
Polaroid 4 x 5. Vary greatly in complexity and degree of sensitivity;
(i.e. manual, semi-automatic or fully automatic.)
Photomicrography - the process of documenting
images on film as seen through a microscope.
Plan Objective - an objective corrected for
flatness of field so that when you view the specimen it is in focus all
across the field. We then have Plan Achromats, Plan Fluorites, and Plan
Polarizing Components - can be added to an
existing basic microscope to locate birefringent materials (i.e.
Rack and Pinion - the
intermeshing of a geared wheel and matching vertical grooved rack to
develop tight accurate focusing.
Ramsden Eyepiece - an eyepiece similar to the
Huygenian eyepiece. It differs in that it has its focal plane either on
or just outside the surface of the collective lenses.
Real Field of View - range (diameter)
of specimen observable with a microscope.
Resolving Power - the ability resolve two
points at a given distance.
Rotational Viewing (360 degrees) - a microscope
set up in such a way that the eyepiece and eyepiece tube can rotate
around horizontally. Several people gathered around the same instrument
can thus view the same specimen without moving, or having to move the
Scanning Electron Microscope - a microscope
which uses a beam of electrons to impact the specimen. Secondary
electrons emitted at the point of impact are imaged by high tech
Spherical Aberration - an optical defect in
which the lens fails to form a sharp image. Rays of light which pass
through a lens near its edge are converged to a point nearer the lens
than those rays passing through the center of the lens.
the platform which hold the specimen.
Stage - moves the specimen East to West and North to South.
Stage - usually rotates 360 degrees or, in the case of a rotating
mechanical stage, as much as 270 degrees.
Stage Clips - fasteners located on the stage
and placed over slides to hold them securely in place while viewing.
Stage Micrometer - used to calibrate the ocular
Stand - the basic component of the microscope
which holds all of the other components. Usually contains the light
Stop Screw - an adjustable screw located at the
base of the focus rack which, when adjusted properly, prevents the body
tube from lowering too far and potentially causing damage to both the
highest power objective and the specimen.
Tube Length - the optical
distance from the objective to the eyepiece. Governs interchangeability of optical components; i.e. a microscope objective corrected for 160mm.
tube length cannot be used on a microscope corrected for infinity.
Turret-mounted - all objectives are attached to
one common rotating nosepiece to allow for quick and accurate objective
positioning during viewing.
Ultra-violet - the portion of the spectrum
where the wavelengths are below the visible spectrum.
Video Microscope - enables
the specimen to be viewed on a video screen. Image can also be analyzed
by a computer.
- "C" Mount (interface between closed circuit TV cameras and
microscope), CCTV Camera, monitor and possibly an image processor.
- Expense in the case of the more specialized systems only.
Virtual Image - an image that does not converge
in real space.
Wavelength - light travels in waves varying in
length. Measurement is from the top of one wave tot he top of the next
one and is usually measured in units of nanometers (nm) or Angstoms (A).
Wide Field Eyepiece - an eyepiece having a
large field of view with a high eye point.
Working Distance - the distance from the front
element of the objective to the specimen.