Introduction to Microscopy - Part One

• With the advent of high resolution microscopes modern microbiologists have access to microscope

• That produces images with high clarity & magnification.

• The Leeuwenhoek’s single lens microscope has been transformed into a high resolution multi-lens combination with magnification upto two thousands time.

• Further electron microscopes with magnification upto one lakh times

• Used to study fine structure of cells and sub- cellular components.

• Microscopes are categories

1. Light (optical) microscopes and

2. Electron microscopes

1.1. Light microscopy involves use of optical lenses and light radiations • Optical microscopes further categorized as

1. Polarizing Microscope, 2. Reflected Light Microscope,

3. Bright field microscopy (Fig. 5b),

4. Dark field (Fig. 5a), 5. Phase contrast microscopy (Fig. 4.a),

6. Fluorescence microscopy (Fig. 4.(b-c)),

7. Confocal Microscope (Fig. 6) - Stimulated Emission Depletion (STED) Microscopy - Laser Scanning Confocal Microscope , - Multiphoton Microscope - Three-Dimensional Optical Microscopy • Electron microcopy is of two types

1. Transmission microscopy and 2. Scanning Electron microscopy 

• Light travels as wave in crests & troughs.

• The amplitude of the crests & troughs determine the brightness of the light.

• The number of time complete wave occur per unit time is called as frequency and the distance between two consecutive crests is called wavelength (λ) of the light.

• Light microscope wavelength in the range 400-700 nm make up visible spectrum.

• While the UV region consists of wavelengths ranging from 100-385 nm.

• Visualizing any object directly by human eye involves incidence & reflection of light in the visual range.

• Microscopes use day light or light emitted by incandescent bulb.

• Fluorescent & UV microscope employ UV radiations.