Light-Microscope

Light Microscope: History, Construction, & Types of Light Microscope

Light Microscope

The optical microscope typically referred to as a light microscope is a kind of microscope that uses visible light and a system of lenses to magnify images of tiny objects. Optical microscopes are the oldest design of a microscope.

The light microscope is an instrument utilized by researchers in several fields to magnify specimens to as much as a thousand times their original size. In its simplest form, it is composed of a clear lens that amplifies the sample and light to brighten it.

Nevertheless, most light microscopic lenses are far more intricate and fine-tuned lenses with firmly managed dimensions all within the body of the microscope itself and in elements such as the objectives and eyepieces.

History of Light Microscope

Light microscopes date a minimum of 1595 when Zacharias Jansen (1580– 1638) of Holland invented a compound light microscopic lens, one that utilized two lenses, with the second lens, even more, magnifying the image produced by the first.

Antony van Leeuwenhoek (1632– 1723) created a simple (one-lens) microscope around 1670 that magnified as much as 200x and accomplished two times the resolution of the best compound microscopic lens of his day.

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Englishman Robert Hooke (1635– 1703) even more refined the compound microscope, adding such functions as a stage to hold the specimen, an illuminator, and coarse and fine focus controls.

The most considerable improvements in the microscopic lens were made by Carl Zeiss (1816– 1888) and Ernst Abbe (1840– 1905). They added the substage condenser and developed exceptional lenses that significantly reduced chromatic and spherical aberration while allowing significantly enhanced resolution and greater zoom.

Construction of Light Microscope

The primary components of a light microscope are eyepiece, lens tube, objective revolver, stage, table, condenser, focus, coarse focus, luminous-field diaphragm, light source, base.

Construction-Light-Microscope

Ocular/ Eyepiece

It is a construction of a minimum of several lenses. The function of the eyepiece in a microscope is to convert the real- enlarged-intermediate-image from the objective into an enlarged-virtual-image.

Objective revolver

Objective revolvers are used in microscopes with multiple objective lenses, that have various zoom elements.

Objective lens

An objective (lens) is that part of an optical system, which is directed to the object. Its function is to gather the light rays, that are reflected from the observed object. The objective produces a real-optical image.

Microscope phase/ cross table

On the stage, one can position the specimen plate with the cover glass on it. By moving the plate, one can choose the part of the things, which one wants to look at.

Condenser

The condenser gathers the rays from the light, so they are protected equally on the specimen. Thus, every part of the object is brightened on the same brightness level.

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Light

The early microscopes utilized concave mirrors to refract light on the objects. Later on, they utilized light bulbs. Most microscopes run with LED light. The light source´s functions to brighten the specimen uniformly.

Types of Light Microscope
Compound Microscope

The simplest optical microscope is the magnifying glass and is excellent to about 10 times magnification. The compound microscopic lens has two systems of lenses for higher resolution.

  1. The ocular or eyepiece that looks into.
  2. The objective lens or the lens near to object

A modern compound microscope under ideal conditions can magnify an object from 1000X to 2000X the specimen’s original size.

Advantages of Compound Microscope:

  • Easy to use and low-cost.

Disadvantages of CompoundMicroscope

  • As magnifying power increases, the field of view diminishes.
  • As magnifying power increases, the depth of focus decreases.
Stereo Microscope

The stereo microscope or stereoscope or dissecting microscope is an optical microscope alternative created for low magnification observation of a sample. The instrument uses 2 separate optical courses with 2 objectives and eyepieces to provide somewhat different view angles to the left and right eye.

Advantages of Stereo Microscope

A stereo microscope is often used to study the surface areas of the solid specimens or to perform close work such as dissection microscopy, surgical treatment, and evaluation.

Used commonly under low magnification has two eyepieces that give the three-dimensional image.

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Downsides:

Only magnifies up to 125X.

Types of modern Light Microscope

Phase Contrast Microscope

This is a type of optical microscope whereby small light variances referred to as phase shifts occur during light penetration into the unstained specimen.

These stage shifts are converted into the image when the light passes through the opaque specimen, the phase shifts brighten the specimen forming a lit up (bright) image in the background.

Dark-Field Light Microscope

This is a customized type of bright field light microscope that has a number of resemblances to the Phase-Contrast microscope. To make a dark field microscope, place a darkfield stop beneath and a condenser lens which produces a hollow cone beam that enters the objective just, from the specimen.

The Fluorescent Microscope

On adding dye molecules, the specimen emits light. The light energy that is released by the excited particle has a long wavelength compared to its radiating light.

The color particle is typically a fluorochrome, that fluoresces when exposed to the light of a particular specific wavelength. The image formed is a fluorochrome-labeled image from the emitted light.

On the basis of Structure
Inverted microscope
  • Observe the specimen from below.
  • Specimen observes on slides.
Upright microscope
  • Observe the specimen from above.
  • Specimen observe cells soaked with culture in a dish.