biology component (microscope)

Basic Equipment Used in Biology Experiments

This equipment is necessary for the basic studies of biology: visualizing cells and organelles, as well as preparing samples of cells or fluids for testing or visualization, dissecting specimens, or mixing chemicals.

1- Microscopes:- Biologists use microscopes of differing powers to see organisms and samples more closely. They are high-powered, extremely expensive, and sensitive pieces of equipment that can make even the smallest parts of a single cell seem clear. Inexpensive light microscopes do, an electron microscope uses beams of electrons. The beams of electrons bring the finest details of the cell into focus and can allow even large molecules to be seen.Light microscopes magnify cells up to 1,000 times. Using the shortest ray of light, which allows the highest resolution, light microscopes can view things as small as 0.2 micrometers in width — that is, 0.0002 mm.
Simple microscope:- A simple microscope uses a lens or set of lenses to enlarge an object through angular magnification alone, giving the viewer an erect enlarged virtual image.
Compound microscope:- A compound microscope uses a lens close to the object being viewed to collect light (called the objective lens) which focuses a real image of the object inside the microscope.

Compound micro-scope

Other microscope:- 

There are many variants of the compound optical microscope design for specialized purposes. Some of these are physical design differences allowing specialization for certain purposes:

• Stereo microscope:-  A low-powered microscope which provides a stereoscopic view of the sample, commonly used for dissection.

• Comparison microscope:-  In which has two separate light paths allowing direct comparison of two samples via one image in each eye.

• Inverted microscope:-  It used for studying samples from below; useful for cell cultures in liquid, or for metallography.

• Fiber optic connector inspection microscope:- It was designed for connector end-face inspection

• Traveling microscope:- It used for studying samples of high optical resolution.

Other microscope variants are designed for different illumination techniques:

• Petrographic microscope:- Whose design usually includes a polarizing filter, rotating stage and gypsum plate to facilitate the study of minerals or other crystalline materials whose optical properties can vary with orientation.

• Polarizing microscope:-  It is similar to the petrographic microscope.

• Phase-contrast microscope:- which applies the phase contrast illumination method.

• Epifluorescence microscope:- It used designed for analysis of samples which include fluorophores.

• Confocal microscope:-  A widely used variant of epifluorescent illumination which uses a scanning laser to illuminate a sample for fluorescence.

• Two-photon microscope:- It used to image fluorescence deeper in scattering media and reduce photobleaching, especially in living samples.

• Student microscope :– An often low-power microscope with simplified controls and sometimes low quality optics designed for school use or as a starter instrument for children.

• Ultramicroscope:- An adapted light microscope that uses light scattering to allow viewing of tiny particles whose diameter is below or near the wavelength of visible light (around 500 nanometers); mostly obsolete since the advent of electron microscopes

• Tip-enhanced Raman microscope:- It is a variant of optical microscope based on tip-enhanced Raman spectroscopy, without traditional wavelength-based resolution limits. This microscope primarily realized on the scanning-probe microscope platforms using all optical tools.

Digital microscope

A miniature USB microscope.

A digital microscope is a microscope equipped with a digital camera allowing observation of a sample via a computer. Microscopes can also be partly or wholly computer-controlled with various levels of automation. Digital microscopy allows greater analysis of a microscope image, for example measurements of distances and areas and quantitaton of a fluorescent or histological stain.

Invention of Microscope:-

The earliest microscopes were single lens magnifying glasses with limited magnification which date at least as far back as the widespread use of lenses in eyeglasses in the 13th century.

Compound microscopes first appeared in Europe around 1620 including one demonstrated by Cornelis Drebbel in London (around 1621) and one exhibited in Rome in 1624.

The actual inventor of the compound microscope is unknown although many claims have been made over the years. These include a claim 35 years after they appeared by Dutch spectacle-maker Johannes Zachariassen that his father, Zacharias Janssen, invented the compound microscope and/or the telescope as early as 1590. 

13th century            -------------------Single lens magnifying glasses .

1620                        -----------------  Compound microscopes        -----------  Cornelis Drebbel 

Component of Microscope:-

All modern optical microscopes designed for viewing samples by transmitted light share the same basic components of the light path. In addition, the vast majority of microscopes have the same 'structural' components (numbered below according to the image on the right):

• Eyepiece (ocular lens) (1)
• Objective turret, revolver, or revolving nose piece (to hold multiple objective lenses) (2)
• Objective lenses (3)
• Focus knobs (to move the stage)
  • Coarse adjustment (4)
  • Fine adjustment (5)
• Stage (to hold the specimen) (6)
• Light source (a light or a mirror) (7)
• Diaphragm and condenser (8)
• Mechanical stage (9)