Redesigned, updated, and only available from Hammacher Schlemmer, this is the desktop magnifier that enlarges and illuminates an entire book or magazine page. Its 93/4" x 113/4 plastic lens provides 3X magnification of a standard 8" x 11" page without requiring you to adjust or reposition your reading material or the magnifier itself. Unlike glass lenses that can be heavy and crack easily, this magnifier's ABS plastic lens is shatterproof and lightweight, providing the same magnifying power of glass but without the weight and fragility. Its integrated 20 white LEDs help to reduce eyestrain and have dimmers to provide your ideal level of brightness for reading, writing, or inspecting coins and stamps. The neck tilts up/down 120º and the body rotates a full 360º. LEDs are rated for 50,000 hours. It plugs into AC with included adapter. Also accommodates four AA batteries for backup or cordless power. Base 11" L x 7 1/2" W x 9 3/4" D.

Today the microscope is used in many capacities. Microbiologists, for example, use the microscope to study cell structures and the cell processes that are responsible for life itself. Specialized low-power microscopes, called stereoscopic binocular microscopes, are used in the assembly of small electronic circuits and for detailed surgical operations. As an industrial tool, the microscope assists in the detection of food spoilage, drug adulteration, and minute structural defects in metals. It also makes possible nanotechnology, which involves the manufacture of materials on the scale of billionths of a meter.

The products we offer are as unique as our name and our merchandise is backed by our Lifetime Guarantee of Satisfaction.

By signing up via text, you agree to receive recurring automated promotional and personalized marketing text messages (e.g. cart reminders) from Hammacher Schlemmer at the cell number used when signing up. Consent is not a condition of any purchase. Reply HELP for help and STOP to cancel. Msg frequency varies. Msg & data rates may apply. View Terms & Privacy.

microscope: definition biology

Choose a language from the menu above to view a computer-translated version of this page. Please note: Text within images is not translated, some features may not work properly after translation, and the translation may not accurately convey the intended meaning. Britannica does not review the converted text.

Compound microscope

The electron microscope requires that the electron beam be in a vacuum, because electrons cannot travel far in air at atmospheric pressure. The column and specimen chamber of the electron microscope are evacuated by pumps. Living specimens cannot be examined with an electron microscope, since they will not survive in a vacuum.

Transparent objects are mounted on a glass slide and lighted from below. The illumination system consists of a condenser lens to focus the light onto the object and either a mirror with an external light source or a built-in light source, commonly a low-voltage tungsten bulb. The iris diaphragm opens and closes to control the size of the cone of light illuminating the object.

Before the invention of electron microscopes, continuous effort was made to increase the resolution of the microscope by using shorter and shorter wavelengths, moving into the invisible ultraviolet region of the spectrum. Ultraviolet microscopes, used in medical research, produce photomicrographs, which reveal details that visible rays would pass over without reflection or refraction. With other developments, such as specialized glass filters, ultraviolet light is also used for excitation of fluorescence—to convert ultraviolet light to visible light—under a microscope.

10 uses of microscope

You can expect to hear from us periodically about: - Exciting New Product Releases - Extraordinary Gift Ideas - The Best, The Only and The Unexpected - Our Rather Famous Private Sale

Light microscope

The high-power compound microscope is a delicate and expensive instrument, requiring skill, training, and patience in its use. The body tube carrying the magnifying lenses has two focusing adjustments—the coarse instrument for moving the tube up or down rapidly and the fine adjustment for very delicate changes. The object to be examined is placed on a flat surface known as a stage. Some stages move horizontally for viewing of different parts of the object. If the object is opaque, such as a mineral specimen, it is lighted from above.

In the beginning there was hardware. Over the decades much has changed at Hammacher Schlemmer. But our original philosophy has remained constant...and still guides us more than 175 years later.

We’ve been busy, working hard to bring you new features and an updated design. We hope you and your family enjoy the NEW Britannica Kids. Take a minute to check out all the enhancements!

Types of microscope

Monocular microscopes have a single body tube and ocular for viewing with one eye. Elaborate research microscopes are binocular. Magnification depends on the objective lens and the eyepiece. There are usually three objectives in a monocular microscope, typically with magnifications of 10, 40, and 100. Magnification is changed by rotating the objectives, which are fitted into a disk called the nosepiece.

In some compound microscopes the eyepiece has a micrometer device for measuring an object. With a “camera lucida” attachment a highly magnified image may be projected on a screen or upon a sheet of paper, where its structure may be traced with a pencil. Some microscopes are equipped with a small viewing screen that fits on the body tube and shows the same image that is seen through the eyepiece.

The magnification in magnetic electron microscopes is determined by the strength of the current passing through the electric and electromagnetic lens coils. The image is focused by changing the current through the objective lens coil. In the optical microscope the image is determined by absorption of light by the specimen; in the electron microscope the image results from a scattering of electrons by atoms of the specimen. Since an atom with a high atomic number scatters electrons more than does a light atom, it appears darker. As the beam passes through a specimen, each tiny variation in the structure of the specimen causes a variation in the electron stream. The image produced is then projected onto a fluorescent screen or recorded on film. The electron microscope, with its tremendous resolving power, can magnify specimens over 50,000 times.

In the late 20th century German-born physicist Gerd Binnig and Swiss physicist Heinrich Rohrer invented the scanning tunneling microscope. Its resolution is so great that it can resolve a single atom. The scanning tunneling microscope uses a metal probe to scan the topography of a substance, tracing out the hills and spaces that correspond to the surface atoms and the spaces between them. When a vacuum is created between the probe and specimen and a voltage is applied to the probe, the result is the tunneling of electrons from the probe to the specimen. The tunneling voltage and current are measured to create an atomic map.

The compound microscope uses a lens called the objective to produce a primary magnified image and another called the eyepiece or ocular to magnify this image. In practice, both objective and eyepiece are actually composed of several lenses to neutralize the optical defects inherent in lenses made of a single kind of glass.

The simple and compound microscopes are called optical, or light, microscopes. That is, they use a beam of light and lenses to magnify objects.

Microscope parts and functions

Photographs may be made by placing a camera over the eyepiece of a microscope. This art is called photomicrography. Although the process is simple in principle, good high-power photomicrographs require great skill.

After translating an article, all tools except font up/font down will be disabled. To re-enable the tools or to convert back to English, click "view original" on the Google Translate toolbar.

The affiliated, independent Hammacher Schlemmer Institute was created in 1983 to rigorously research, test and rate products to make the Best products available to our customers.

In 1924 the French physicist Louis de Broglie suggested that electron beams might be regarded as a form of wave motion, similar to light. Furthermore, he reasoned that the actual wavelength of such a beam would be much shorter than that of a beam of light.

Zacharias Janssen is credited with having invented the compound microscope in about 1590. With it, remarkable scientific discoveries were made in the 17th and 18th centuries. The Dutch naturalist Anthony van Leeuwenhoek produced lenses powerful enough to prove that many tiny organisms are not spontaneously generated but come from eggs; and the Italian physiologist Marcello Malpighi was the first to see the capillary circulation of the blood.

Many objects too small to be seen with the unaided eye can be viewed through a microscope, an instrument that produces magnified images of such objects. The development of the microscope greatly affected human life. Before it was invented, little was known about tiny organisms such as bacteria and protozoa.

Who invented the microscope

The scanning electron microscope reveals the surface structure or topography of objects directly. Like the transmission electron microscope, it has an electron gun, condensers, and objectives. Its extremely narrow beam of focused electrons moves over, or scans, the specimen. Two types of electrons—backscattered and secondary—are emitted from the surface of the specimen. Each type has its own detector. Backscattered electrons move in straight lines, whereas secondary electrons move in curved paths. The emission of secondary electrons allows for the fine detailing of electron micrographs.

The field-ion microscope, developed in the early 1950s, uses positive ions instead of electrons to magnify an object. It can enlarge an object over one million times. Because of the stresses that specimens are subjected to, however, it cannot be used to view biological objects. It is used in metallurgy for direct observation of defects, radiation damage, or chemical reactions in metal crystals. The proton-scattering microscope is used to observe metal crystals. It accelerates and focuses a proton beam from an ion source or gun onto a crystal target. The pattern of scattered protons is recorded on a fluorescent screen as an image.

Since the image formed by a microscope can be projected upon a screen, the magnification possible is virtually unlimited. Beyond a certain point, however, increased magnification merely makes the image larger without revealing any more detail. Thus the quality of a microscope is not judged by its magnification but by its resolving power—that is, its ability to show separation between lines that are extremely close together.

German electrical engineer Ernst Ruska invented the electron microscope in the early 1930s. The electron microscope is so named because it directs a beam of electrons rather than light through a specimen. The beam of electrons is created in a hot tungsten filament in an electron gun. This beam then travels through the length of the microscope cylinder, which houses the lenses, the specimen chamber, and the image-recording system. Two types of electron lenses are used, electrostatic and electromagnetic. They create electric and electromagnetic fields to both concentrate and move the beam.

What ismicroscope in science

The transmission electron microscope is used to observe very thin slices of a specimen. It has an electron gun and condenser lens system, which create and concentrate an electron beam. The electrons pass through an objective lens before reaching the specimen on the movable stage. Intermediate and projector lenses focus the electrons passing through the specimen to form an electron image. The image-recording system converts the electron image into a form that is perceptible to the human eye.

Items that we sell are guaranteed for their normal life under standard non-commercial use. Should any product fail to meet your expectations, we will replace it or refund the cost of the item less shipping and service fees. Returns older than one year will be credited in the form of a gift certificate.

The objective lenses are usually responsible for both the magnification and the quality of the image. Modern microscopes no longer suffer from the aberrations of earlier biconvex lenses. Chromatic aberration produces color fringes around the edges of the image. Spherical aberration causes a hazy, low-contrast image. Image resolution with achromatic lenses typical of modern microscopes is near theoretical perfection.

Sometimes called a magnifier, the simple microscope consists of a single lens or a set of lenses close to one another. This allows direct magnification. On a magnifying glass, or reading glass, the lens is mounted with a handle. To achieve the largest possible field of view, the lens is held close to the eye. Focusing is achieved by adjusting the distance between the lens and the object being viewed.

This microscope was developed in 1903 to study colloidal particles. These tiny particles—larger than atoms but too small to be seen with an ordinary optical microscope—are suspended in a liquid and illuminated from the side. Their positions and movements are recorded as flashes of intense light on a dark background. Particles as small as 5 to 10 millimicrons are observed. (1 millimicron equals 10 millionths of a centimeter, or 39 billionths of an inch.)