Glossary of Microscope Terms
Below is a list of common microscope terms and glossary definitions.
Abbe Condenser: The Abbe condenser situates under the stage of the microscope. It concentrates and controls the light that passes through the specimen and enters the objective. It has two controls, one which moves it closer to or further from the stage, and the iris diaphragm which controls the diameter of the beam of light. These controls are used to optimize brightness, evenness of illumination, and contrast. Abbe condensers are particularly important for magnifications of above 400X and recommended to match the numerical aperture (NA) of the objective.
Achromatic Objective: Corrects for color and yields a flat field of approx. 65% through the periphery. This is the basic objective found on school or entry-level microscopes – generally sharp 80% to the periphery or to the edge of the field of view (FOV).
Alignment: When the prisms are properly set or synchronized they yield the viewer one image while viewing through one or two eyepieces.
Automatic Light Control (ALC): The level of light is adjusted by the microscope in order to maintain the same level as the one the user has chosen, no matter if the aperture of the diaphragm changes, another objective is inserted, the opacity of the sample changes, etc. This is exclusively offered on many Optika Microscope Models.
Amoeba: Single-celled organisms who could change their shape – simplest of protozoa. Found in pond water and generally viewed in entry-level science classes. Click Here for more details.
Apochromatic Objective: An apochromat or apochromatic objective is a lens that has a better correction of chromatic and spherical aberration than the common achromat lenses and made of higher quality glass. The APO lens is usually of three elements and brings the light of three different frequencies to common focus.
Articulated Arm: A type of stand that holds a microscope body. The stand clamps to a table or mounts to a wall and offers a variety of movements and flexibility in viewing the specimen.
Betrand Lens: An accessory lens found in more sophisticated Polarizing Microscopes and generally inserted above the analyzer in a transmitted light microscope. Generally used in conjunction with a quarter wave plate or first-order red compensator. The lens was first used in 1878 by E. Bertrand who adapted an original design in 1844 by G. B. Amici.
Binocular Microscope: A compound microscope allows the user to view with two eyepieces down a single optical prism and objective lens. In contrast to a stereo microscope, which has a separate optical prism for each eye.
Biological Microscopes: Are compound microscopes, either monocular or binocular/trinocular that are used for viewing plant, animal or living organisms. They are mostly brightfield but can also be phase contrast, fluorescent or inverted microscopes. (Fluorescent Microscopes use microscopes but can also be Mercury, Xenon or Metal Halide bulbs) They are commonly equipped with three objectives- 4x, 10x & 40x or four objectives that include the 100x oil immersion objective & abbe condenser with mechanical stage. The illumination is either tungsten, halogen or LED, and even used cordless for portable field applications.
Biology: Is the study of life in a living plant, animal and human organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines.
Brightfield Illumination: Lighting that shines through a transparent specimen highlighting internal detail structures which appears dark against a bright background. Also called transmitted light illumination. This is opposite of darkfield illumination.
C-mount: Common microscope camera adapter used with video or digital cameras. The adapter usually fits on the trinocular port of the microscope. It should match the chip size of the camera sensor. (ie – .5x camera lens connects to a .5x digital adapter)
CCD Sensor: Charge-Coupled Device. is the light-sensitive chip used to capture images; is the light-sensitive chip used to capture images; an optical sensor converts light into electronic signals for high-quality images. In essence, CCDs control how an image is captured. Commonly used for Phase Contrast, Dark-field and Fluorescence applications
CMOS Sensor: Complementary Metal Oxide Semiconductor, each pixel has its own charge-to-voltage conversion, and the sensor often also includes amplifiers, noise-correction, and digitization circuits, so that the chip outputs digital bits.
Coarse Focus: The larger rough focus knob on the microscope closest to the frame or body of the microscope. This moves the stage/platform towards or away from the specimen while the objectives are in a fixed position. (Rare exceptions this will move the nosepiece that holds the objectives towards or away from the specimen.) Use before fine focus and then continue with fine focus when changing objectives.
Compound Microscope: A generic term that describes all configurations and type of binocular, monocular, trinocular but not stereo microscopes. Also synonymous with high-power microscopes that features multiple lenses of varying magnifications used to present a two-dimensional image.
Common Main Objective: Found on higher-end research grade stereo microscopes. Two parallel optical paths sharing one common large objective defines the Common Main Objective design. Offered on the Unitron Z10 & Meiji RZ Series
Darkfield Illumination: Darkfield Microscopy is primarily used for unstained, transparent and opaque objects such as marine organisms, fungus, insects, and bacteria where light is reflected off the specimen that is placed against a dark background. A darkfield microscope is a microscope designed to permit diversion of light rays and illumination, from the side, so that details appear light against a dark background; as opposed to light passing straight through the specimen as in brightfield illumination. Darkfield illumination is a low-cost alternative to phase contrast optics. Nowadays common use is for live blood cell analysis.
Digital Microscope Camera: These digital cameras are strictly manufactured for use with microscopes that includes the following accessories; USB cable, comprehensive software that can capture, store and photo editing capabilities. These digital cameras can not be used without the microscope. In other words, they are not consumer-type digital cameras found in the camera store.
Digital Microscope: A microscope and digital camera combination that provides a digital output such as USB or Firewire for connection to a computer. Often includes software to display and process the image on a PC or laptop.
DIN Standard: An German international standard (Deutsches Institut für Normung) which dictates the design compatibility of microscope optics with 160mm tube length. Found in entry-level and professional, medical and educational microscopes.
Dual-head Microscope: A monocular microscope with a second viewing port. The vertical port can be used with an eyepiece for an instructor to view the specimen, or used with an adapter and camera. Also referred to as a teaching microscope for two or more users.
Electron Microscope: Light microscopy is governed by its use of visible light, which limits resolution. The shorter the wavelength of the illumination, thus the better the resolution. Electron beams have shorter wavelengths than photons. The co-invention (by two Germans; – Ernst Ruska and Max Knoll) of the electron microscope in the late 1930s and its refinement over the next half-century allowed for improved visualization of cell and tissue fine structure.
Eyepiece: The lens closest to your eye when looking through a microscope. A binocular or stereo microscope will have two matching eyepieces, a monocular microscope will have one eyepiece. They generally range from 18mm to 22mm FOV. The larger FOV isn’t always better as it needs to match the objective, otherwise spherical aberrations may appear.
Eyepiece Micrometer: Generally a linear scale or available in many designs etched on an eyepiece lens. It is used to make measurements of the size of objects seen through a microscope. Also called a reticle.
Fluorescence Microscope: is a light microscope, either upright or inverted w/ external light source and power supply, also called Epi-Fluoresence. Fluorescence Microscopes are equipped to examine organic or inorganic material that fluoresces under ultraviolet light. Based on the principle that fluorescent materials emit visible light when they are irradiated with ultraviolet rays or with violet-blue visible rays. Fluorescent stains (one commonly known as Dapi) are used with the material in order to facilitate the fluorescence process. Uses a much higher intensity light to illuminate the sample. This light excites fluorescence species in the sample, which then emit light of a longer wavelength. The most common type of fluorescence illumination uses mercury bulbs w/ power supply……earlier versions were xenon or halogen bulbs. The newer versions use metal halide or LED Fluorescence Illumination.
Fiber Optic Illumination: Bright intense light (utilizes fiber optic technology) with power supply available with single or bifurcated cables. Freestanding or attaches to the stereo head called Fiber Optic Ring Illuminator.
Fluorescent: A whitish light source based on a gas discharge process. The primary benefit is the amount of heat generated by the illuminator is severely reduced from a traditional tungsten filament light.
Fluorite or Planfluorite: Objectives provide correction for four wavelengths chromatically and spherically over a correspondingly wider spectrum. ( 100% sharpness to periphery) They are among the most expensive and use a higher quality glass.
Genetics: The study of heredity or inherited characteristics through the study of genes in organisms of humans, animals, and plants. For example.where a parent passes on certain genes/traits/characteristics to their children or offspring – such as hair, skin or eye color.
Hemocytometer: A hemocytometer is a square chamber carved into a piece of thick glass that has a specific depth. It is used to calculate the density of cells in suspensions. ..The hemocytometer was invented by Louis-Charles Malassez who was trying to count blood cells.
Infinity Plan: The highest quality flat field of focus for 100% of the field of view projecting the image to infinity. Parts of the specimen at the edge of the field of view are as well-focused as the center part of the specimen.
Immersion Oil: A special oil used in microscopy with the objective. A drop is placed upon the coverslip or slide and the objective is lowered until it just immerses. The oil acts as a bridge between the glass slide and the glass in the lens, increasing the resolution of the image. Required for all 100x Oil Immersion Objectives. Special 40x, 50x, 60 & 80 may require oil.
Infinity Corrected Optics: Over the past 10 years, the major microscope manufacturers have largely all migrated to the utilization of infinity-corrected optical systems in both research-grade biomedical and industrial microscopes. In these systems, the image distance is set to infinity, and a tube (or telan) lens is strategically placed within the body tube between the objective and the eyepieces (oculars) to produce the intermediate image.
Incident or Reflected Light: Where the light path originates from the top (situated in a housing in the rear of the upper frame behind the head ) travels through the objectives…..Metallurgical or Fluorescence Microscopes are common types.
Inverted Microscope: The objectives are situated below the stage and the light travels through the objectives. Used for medical or industrial applications that require a large work surface.
Koehler Illumination: Features on the microscope that maximizes the illumination for transmitted or epi-illumination with controls at the illuminator housing for centering, aligning, focusing and concentrating the beam of light and a field diaphragm for additional fine-tuning at the base. Additional centering controls on the Abbe condenser.
LED Illumination: (Light Emitting Diode) New lighting technology whereas the bulb last thousands and thousands of hours and produces virtually no heat. Available in 1,3 or 5 watts.
Light Microscope: (LM) is generally referred to as compound microscope (opposed to stereo) that uses external light drawn by a mirror from ambient light or built-in electric source with LED, halogen or tungsten light combined with magnifying lenses (objectives) to examine small objects not visible to the unaided eye. The effectiveness of any microscope is that it produces better resolution than the eye alone can visualize. Resolution is the ability to distinguish finer details of cells or objects. The inventions of polarized and phase contrast microscope, digital and video attachments all have enhanced resolution in a light microscope.
Live Blood Cell Analysis: The method whereas blood cells are analyzed to determine the health of the patient using darkfield or phase contrast microscopes. Recommendations are made based on the findings.
Magnification: Generally refers to the number on the objective. Therefore a 4x objective is simply 4x. A 10x objective is 10x, etc. and sometimes the eyepiece is also referred to as magnification. The eyepiece multiplied by the objective achieves total magnification.
Mechanical Stage: A mechanical device part of or connected to the stage that allows one to move the specimen slide in the X or Y direction in a precise distance by turning a knob. Very useful at higher magnifications from 40x objective (400x with 10x eyepiece) and above. Nowadays some manufacturers go with the rackless mechanism as opposed to racks with teeth that may deteriorate over time.
Metal Halide: Latest lighting technology (very expensive) for fluorescence microscopy, intense illumination in competition to the mercury and xenon arc lamps for investigations in fluorescence microscopy. These light sources feature a high-performance arc discharge lamp housed in an elliptical reflector that focuses the output into a liquid light guide for delivery to the microscope optical train.
Metallurgical Microscope: Used for viewing circuitry and metal components. Available in Reflected / Incident Light, Transmitted Light or both.
Microscope: An optical instrument that uses a lens or a combination of lenses to produce magnified or enlarged images of small objects, especially of objects too small to be seen by the naked eye used to see microscopic objects, either compound or stereo.
Mirror and Fork: Two-sided mirror with convex and concave side positioned or tilted at the correct angle in order to gather the maximum light from an artificial light source such as desk lamp or ambient light. Generally found on monocular microscopes.
Monocular Microscope: A compound microscope generally with a built-in prism and one eyepiece available in a vertical or inclined tube.
Nomarski & DIC: Differential interference contrast (DIC) microscopy, also known as Nomarski Interference Contrast (NIC) or Nomarski microscopy, is an optical microscopy illumination technique used to enhance the contrast in unstained, transparent specimens.
Numerical Aperture (NA): The measure of the diameter of the aperture (opening) compared to the focal length of the lens and it indicates the resolving power of a lens. A lens with a larger numerical aperture will be able to visualize finer details than a lens with a smaller numerical aperture.
Objective: The lens in a microscope (screwed into nosepiece) closest to the specimen that gathers light from the object being observed and focuses the light rays to produce a real image. In a compound microscope there are usually 3 to 5 objective lenses allowing a selection of different magnification powers. Typical are x, 10x, 40 & 100x Oil Immersion. Others available, varying from manufacturer.
Optical Microscope: Or microscope are among the oldest design of microscope from around 1600 constructed by Johannes and Zacharias Janssen. Anton Leeuwenhoek was the first to describe cells and microorganisms using an optical microscope. Basic optical microscopes can be very simple and they generally consist of light source, condenser, objective lens and an ocular or eyepiece which can be replaced by or a digital camera for recording or capturing images. Through the years many variations such as phase contrast or fluorescent microscopes improve resolution and contrast.
Organism: The cell is the functional basic unit of life. It was discovered by Robert Hooke and is the functional unit of all known living organism. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. Some organisms, such as most bacteria, are unicellular (consist of a single cell). Other organisms, such as are humans are multi-cellular.
Paramecium: Is larger than the ameba. It can be found in ponds with scum on them. It has more of a shape than an ameba, looking like the bottom of a shoe. It is covered with tiny hairs that help it move. These hairs are called cilia. The paramecium is able to move in all directions with its cilia.
Phase Centering Telescope or Eyepiece: Is a focusing eyepiece used with phase contrast microscopes that have a zernike type condenser. This allows for the proper aligning or centering of the phase annulus in the condenser to the objective, whereas the two circles of light rings overlap to form a complete circle rather than a distorted one.
Phase Contrast: Contrast enhancing technique developed by Frits Zernike in the 1930’s but officially recognized in 1953 for which he won the Nobel Prize in Physics. The technique shifts the light phase wavelength, thereby causing the the light deviated by the specimen to appear dark on a light background. This optical technique is used to better view the structure of transparent objects including live organisms (protozoa, bacteria or sperm) or blood in live blood cell analysis. Found on advanced microscopes with a Zernike type Condenserwith a full set of phase objectives – 10, 20x, 40x & 100x or as a simple phase with two objectives – 10x or 40x phase objectives.
Plan Acrhomat Objective: Almost 100% sharpness to periphery/edge of field of view (FOV) equipped on professional and clinical grade microscopes. Corrects better for color and spherical aberration than acrhomat or semi plan objective. Generally larger working distance and more expensive.
Plan Apochromatic Objective: These are the best objectives for critical resolution and color photomicrography, ( 100% sharpness to periphery) and they usually have shallower depth of field than the other objectives. provide greater resolution chromatically and spherically than the other objectives and more expensive than the Plan Achromat Objectives.
Protozoa: Single celled organisms and smallest of all animals commonly found in pond water. They do breathe and reproduce like multicell animals. Included in this group are paramecium, euglena and ameba. Generally viewed in entry level science classes. Click Here for more details.
Rack and Pinion: A microscope focusing mechanism where the rack is a track with teeth and the pinion is a gear that travels up and down the track. By turning a focus knob, the microscope moves closer or further away from the specimen.
Reticle: Generally a linear scale or available in many designs etched on an eyepiece lens. It is used to make measurements of the size of objects seen through a microscope. Also called an eyepiece micrometer.
Seidentopf Binocular Head: Two eyepieces, with the 360° rotating head designed so that by increasing or decreasing the distance between the two eyepieces (interpupillary distance) is done by twisting the eyepieces in an up and down arc motion similar to most binoculars.
Semi-Plan Objective: Semi-plan objectives show sharper images and less aberration in the outer edge (periphery) of the FOV than acrhomat objectives. A step up from Achromat Objectives, provider greater sharpness and color contrast to 85%- 90% to periphery/edge of field of view (FOV). Equipped on upgraded and professional microscopes.
Simple Phase Contrast Microscope: Phase contrast microscope generally with two pre-centered phase sliders built into the condenser and two – 10x & 40x phase objectives – A simple version of a full phase contrast microscope.
Simple Polarizer & Analyzer: Consists of two polarizing filters, one is inserted above and on top of the light source and the other, sits in between the objectives an eyepieces resting in place where the head is attached to the frame or body.
Slide: A flat glass or plastic plate that transparent specimens are placed on. General size is 1×3″.
Specimen: The object that is being viewed. Compound microscopes generally view slides, (some case petri dishes and flasks) Stereo microscopes view large objects such as plants, circuitry, rocks or gems, etc.
Stage Micrometer: A Stage Micrometer is simply a microscope slide with a finely divided scale marked on the surface. The scale is of a known true length and is used for calibration of optical systems with eyepiece reticle or graticule patterns. This is particularly important when alternating between objectives on one microscope or when using the same graticule in different microscopes.
Stereo Microscope: A microscope with two eyepieces that incorporate separate optical paths housing prisms for each eye that allows viewing of specimens in three dimensions.
Teaching / Multi-headed Microscope: Refers to two or more users with one body.
Tension Control: Is a knurled knob found on some microscopes that is located closest to the frame. If the stage is drifting then tighten the knob in the clockwise direction. If the coarse control is to tight then loosen or turn the know in the counter clockwise position.
Total Magnification: Is the total size of the specimen as seen by the naked eye while viewing through the microscope. This is accomplished by multiplying the eyepiece with the objective. Therefore a 10x eyepiece x 4x objective = 40x total magnification.
Trinocular Microscope: A binocular microscope with a third viewing port. The third port can be used for an instructor to view the specimen, or be used with a digital or video camera.
Working Distance (WD): The distance between the specimen and the objective lens. This dictates the allowable movement of the objective.The lower power offers greater working distance and the higher the magnification of the objective lens offers less working distance.
Zernike Condenser: Generally includes a set of four phase annulus rings (10x, 20x, 40x & 100x) built into the condenser – rotates and aligns with the respective rings built into the 10x, 20x, 40x & 100x phase objectives. Once properly aligned with a phase centering telescope, the results are cells structures appear light and discernible against a dark background. This allows for live specimens such as bacteria or sperm to be viewed without destroying or changing their shape. Named after Frits Zernike.
Zoom: The knob or the housing around the lower lens of a stereo microscope that provides variable magnification levels while maintaining focus. Consists of a combination of lenses and gears located internally. Located on the top, side or bottom of the pod. ie. 7-45x zoom offers all magnifications from 7x, 8x, 9x, etc to 45x….
If you have any questions about our glossery of microscope terms or would like to place an order for a microscope, then please contact our team at MicroscopeInternational.com.