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Glossary of Microscope Terms

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 Lens: A combination of lenses made of different glass, used to produce images free of color distortion

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 periphery or to the edge of 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, opacity of the sample changes, etc. This is exclusively offered on many Optika Microscope Models.

Ambient Light: The available light in a room or outside whether it be from the sun or from external light source

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 better correction of chromatic and spherical aberration than the common achromat lenses and made of a higher quality glass. The APO lens is usually of three elements and brings 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.

Auxiliary Lens: Additional lens used with stereo microscopes to increase or decrease magnification or working distance.

Bacteria: Single cell organisms; either rod, sphere or spiral shaped..they do not have a nucelus.

Betrand Lens: An accessory lens found in more sophisticated Polarizing Microscopes and generally inserted above the analyzer in atransmitted light microscope. Generally used in conjunction with 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 can 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.

Body: Or frame of the microscope that connects the head and base. Houses the focusing mechanism, nosepiece, stage and condenser.

Body Tube: Separates the objectives and the eyepiece(s) and assures continuous alignment of the optics.

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 to 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)

Calibration: The calculation in determining the true distance or size of specimen when using an eyepiece reticle, based on the small lines that are seen on the reticle.

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

Cell: Is the basic functional of life. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life.

Chromatic Aberration: The edge of the field of view (FOV) appears as a mix of color like a rainbow.

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 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.

Coaxial Controls: A configuration where the larger coarse adjustment focus knob is centered on top of the smaller fine focus knob.

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

Condenser Lens: A lens mounted in the stage/platform whose purpose is to focus or condense the light onto the specimen. Condenser lenses are not used on low-power (stereo) microscopes.

Cover Slip: A thin piece of glass or plastic placed over the specimen on a microscope slide. Assists with single-plane focusing and protects liquids such as blood and urine from spilling over.

Darkfield Illumination: Dark field 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.

Diopter Adjustment: In binocular microscopes, a control on the ocular tube(s) used to compensate for differences in vision in each eye by clockwise or counter clockwise.

Dissecting Microscope: Another term for a stereo microscope.

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.

Epi Fluorescence: See Fluorescence Microscope.

Euglena: Is unique because it is sort of like a plant and also like an animal. It is pear shaped. It has a tail that whips and is called a flagellum that allows it to move through the water.

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.

Eyepiece Tube: The barrel that the eyepiece sits inside and connects to the nosepiece.

Fine Focus: The knob(s) used to fine-tune the focus on the specimen. Sometimes with graduated increments or indents.

Field of View (FOV): The diameter of view that you see when looking into a microscope. Typically you will see 4.5mm at 40X, 1.8mm at 100X, and 0.45mm at 400X.

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 bifricated cables. Free standing or attaches to stereo head called Fiber Optic Ring Illuminator.

Fiber Optic Ring Illuminator: Bright intense light (utilizes fiber optic technology) with power supply attaches to stereo head. Available with most manufacturers. Used where most light is required.

Fluorescent: A whitish light source based on a gas discharge process. Primary benefit is the amount of heat generated by the illuminator is severely reduced from a traditional tungsten filament light.

Fluorescent Ring Light: Illuminator with low heat fluorescent bulb attaches to stereo pod

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.Most Expensive type of objective.

Focal Distance: The distance between the end of an objective and the surface of the specimen.

Focal Point: In microscopes, as magnification increases the focal distance decreases.

Focus: A means of moving the specimen closer or further away from the objective lens to obtain a sharp image. Rack-and-pinion is a popular type of focus mechanism.

Focus Mechanism: Refers to the Coarse and or Fine Adjustment that brings the image into focus.

Frame: Or body of the microscope that the head or pod is connected to and the lower portion is connected to the base. The focus mechanism is built into the frame.

Frtiz Zernike: Discovered phase contrast microscopy in the 1930s. The Zernike condenser was named for his accomplishments. Awarded Nobel prize for physics in 1953.

Genes: Tiny biochemical structures inside each cell called genes carry traits from one generation to the next.

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.

Gout Microscopes: Biological polarizing type microscope used for viewing synovial fluids – consists of polarizer,analyzer and full wave plate.

Graticule: See Reticle.

Halogen: Microscopes with halogen lamps emit more intense white light, but also emit a considerable high heat which can quickly destroy living specimens.

Head: The upper part of the microscope that contains the eyepiece tube and prisms. Generally referred to in binocular or trinocular or stereo configurations.

Huygenian Eyepiece: Standard found in earlier and older microscopes that offers smaller field of view (FOV) than widefield eyepieces.

Infinity: The objective lenses are designed to project their images to infinity, not to some finite distance. It provides an “infinite” region of parallel light between objective and eyepiece.

Infinity Achromatic: A quality flat field of focus for 60% of the field of view projecting the image to infinity.

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.

Infinity Semi-Plan: A high quality flat field of focus for 80% of the field of view projecting the image to infinity.

Immersion Oil: A special oil used in microscopy with the objective. A drop is placed upon the cover slip 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.

Interpupillary Distance: Distance between the two eyepieces of a microscope. Typically it is adjustable to accommodate different users. Ranges from approx. 48mm -75mm.

Inverted Microscope: The objectives are situated below the stage and the light travels through the objectives. Used for medical or industrial applications that require 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 LEDhalogen 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.

Macro: Larger size specimens.

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 manufactures goes with 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.

Micro: Smaller size specimens.

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.

Microscopic: When the specimen is to small to be viewed by the naked or unaided eye.

Microscopy: Is the means of using a microscope for viewing specimens invisible to the eye.

Mirror and Fork: Two sided mirror with convex and concave side positioned or tilted at 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.

Mohs Microscopes: Biological microscope used for diagnosis of skin cancer – consist of lower power objectives – generally 1x or 2x and up to 40x magnification.

Monocular Microscope: A compound microscope generally with built in prism and one eyepiece available in 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.

Nosepiece: Also called the turret, the part of the microscope that holds the objective lenses. Better quality has ball bearings.

Nucleus: Control center of cell, with DNA (hereditary information) and controls the cells growth and reproduction.

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.

Ocular: See Eyepiece

Optical Microscope: Or microscope are among the oldest design of microscope from around 1600 constructed by Johannes and Zaccharias JanssenAnton 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.

Parcentered: Is when the specimens remain centered in the field of view at multiple magnification levels without having to move the slide.

Par-focal: A lens design such that allows specimens to remain focused at different magnification powers. Periphery refers to the edge of the FOV while viewing through the eyepiece.

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.

Plan Objective: A lens that is corrected for flatness of field, so when in focus the entire image is greatly enhanced and 100% of the field of view is in focus.

Pod: Refers to the stereo head. Available in zoom (magnification from 1-4x and everything between or turret style – generally 1x & 3x or 2x & 4x).

Post Stand: A type of stand used with low-power stereo microscopes. The microscope body can rotate around the post and also up and down.

Positive Click Stops: Like a zoom with stops or detents while turning the magnification dial. Found in higher end stereo microscopes.

Prism: The combination of glass in the head of the microscope form an optical aligned path for viewing.

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.

Rack Stop: Keeps the user from cranking the objective lenses too far down preventing damage to the objective or glass slide. Generally consists of a set screw or knurled knob.

Resolution: The ability of a lens to show fine details of the object being observed.

Reflected Light (illumination): see Incident light.

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.

Retractable Objective (XR): A spring located inside the objective lens so that minimal damage is done to the slide and the top element of the lens should the microscope be cranked down too far.

Ring Light: An external light source that usually attaches to the microscope body and gives off a 360° ring of light. Also called annular light. Available in Fluorescent, LED or Fiber Optic.

RMS: Royal Microscope Society's standard threading for objectives/nosepiece for microscopes with 160/170mm tube length. (36 threads per inch).

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".

Slip Clutch: A mechanical device that protects the focusing system of the microscope and preventing the either of the coarse or fine focus from cranking to far up or down.

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.

Spherical Aberration: The edge of the field of view (FOV) is blurry.

Stage: The platform where the specimen is placed for observation.

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.

Stage Plate: Used in Stereo microscopes. The specimens are placed on this surface. Generally available in clear glass, frosted or black and white.

Stereo Head: Or Pod refers to the upper portion of a Stereo Microscope where the Prisms are housed.

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.

Supplemental Lens: See Auxiliary Lens.

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.

Transmitted Light (illumination): See brightfield illumination.

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.

Tungsten: A light that gives intense, white light, but also emits considerable heat which can quickly kill living specimens.

Turret: Also called the nosepiece, the part of the microscope that holds the objective lenses. Better quality has ball bearings.

Widefield Eyepiece: offers wider field of view (FOV), (then Huygenian) generally 18mm & 20mm for most microscopes and 21 & 22mm and higher for better grade microscopes.

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….

160mm Tube Length: The actual tube length from the eyepiece to objective – previous generation of microscopes from the 1980's that offered Achromat, Semi Plan, Plan and Fluotar Objectives.

170mm Tube Length: The actual tube length from the eyepiece to objective – earlier generation of microscopes prior to the 1980's that offered Achromat, Semi Plan, Plan and Fluotar Objectives.