Biological Microscopes

Biological microscopes are used to study organisms and their vital processes.  Microscopes used in this field range widely, from relatively simple optical microscopes to very advanced imaging systems used in cell research, forensic medicine, and state-of-the-art high resolution molecular studies.  The most common configurations of biological microscopes are student, benchtop and research.  Student microscopes are the smallest and least expensive type of microscope. They are capable of advanced techniques and documentation even though they are for student use. Benchtop microscopes are used in various industries like textiles and animal husbandry.  Benchtop microscopes can do many techniques but are limited by the amount of techniques they can be used for at one time.  Research microscopes are large, weighing in the range of 30Kg to 50 Kg. This mass is composed of complex optical, mechanical, and electronic systems. They may use multiple cameras, large specimens, and the widest range of simultaneous techniques.

Biological microscopes can be one of many types of technologies.  The most common biological microscopes are compound microscopes used for viewing very small specimens such as cells, pond life samples, and other microscopic life forms, inverted microscopes, which are better for looking through thick specimens, such as dishes of cultured cells, because the lenses can get closer to the bottom of the dish, where the cells grow and stereomicroscopes which are great for dissecting as well as for viewing fossils and insect specimens.  Other technologies include acoustic and ultrasonic microscopes, microwave microscopes, fluorescent microscopes, laser or confocal microscopes, polarizing microscopes, portable field microscopes, scanning electron (SEM) microscopes, scanning probe or atomic force microscopes (SPM / AFM), and transmission electron microscopes (TEM).

The magnification of biological microscopes is the ratio of the size of an image to its corresponding object. This is usually determined by linear measurement.  Resolution is the fineness of detail in an object that is revealed by an optical device. Objectively, resolution is specified as the minimum distance between two lines or points in the object that are perceived as separate by the human eye. Subjectively, the images of the two resolved points must fall on two receptors (rods or cones), which are separated by at least one other receptor on the retina of the eye.  Field of view is defined as the extent of the visible image field that can be seen when the microscope is in focus.

Biological microscopes can come in one of many types of eyepiece styles.  These include monocular, binocular, trinocular or dual head.  A monocular eyepiece has one objective and one body tube for monocular vision.  Binocular microscopes are fitted with double eyepieces for vision with both eyes. The purpose in dividing the same image from a single objective of the usual compound microscope is to reduce eyestrain and muscular fatigue, which may result from monocular, high-power microscopy.  These types of microscopes are also used for stereoscopic vision, which allows for depth perception of the sample.  Trinocular microscopes are fitted with a vertical tube at the top and regular binocular eyepieces at 30 degrees.  The vertical tube is often used for a digital camera or a second observer.  A dual head has one vertical eyepiece lens and a second eyepiece off the side at 45 degrees (So that two people can view the sample at one time, or one person and a camera.  Important features in specifying biological microscopes include a digital display, mechanical stages, oil immersion lenses, fine focus, computer interfaces, and image analysis processing software.