Microscopy is the science of investigating small objects and structures using microscopes. There are various types of microscopes that use different principles. Light microscopy is the simplest form and uses electromagnetic radiation to achieve magnification. Key components of light microscopes include the objective lenses, which collect light and form an image, and the condenser, which controls the illumination. Other important concepts are magnification, which enlarges the apparent size of an object; resolution, the ability to separate two close points; and numerical aperture, a measure of how much light a microscope can collect that determines resolution. Refraction of light is important for microscopy and depends on the refractive index of materials.

1. MICROSCOPY
DR.P.NITHIYA
ASSISTANT PROFESSOR
DEPARTMENT OF BOTANY
SEETHALAKSHMI RAMASWAMI COLLEGE
TIRUCHIRAPPALLI

2. Microscope and Microscopy
A microscope (from the Ancient Greek: μικρός,
mikrós, "small" and σκοπεῖν, skopeîn, "to look" or
"see") is an instrument used to see objects that are
too small to be seen by the naked eye.
Microscopy is the science of investigating small
objects and structures using such an instrument.

3. MICROSCOPY
 Microscopy comprises of the tools that are used to see/image
the microscopic objects and even macromolecules.
 There exists a wide variety of microscopic tools for studying
the biomolecules and biological processes.
 Light microscopy is the simplest form of microscopy. It
includes all forms of microscopic methods that use
electromagnetic radiation to achieve magnification.
 In this lecture, we shall be discussing the principles of
microscopy.

4. Magnification

5. Magnification
 Magnification is the process of enlarging the apparent size, not physical size, of
something. This enlargement is quantified by a calculated number also called
"magnification".
 When this number is less than one, it refers to a reduction in size, sometimes
called minification or de-magnification.

6. Resolution

7. Light Microscope

8. price of TEM microscope

9. Resolution
 Resolution is the fineness of detail in a bitmap image and is measured in pixels
per inch (ppi).
 Resolution is the ability to separate two points

11. Resolution
 The resolution of an optical microscope is defined as the shortest distance
between two points on a specimen that can still be distinguished by the observer
or camera system as separate entities.

12. Resolution

13. Numerical Aperture
The numerical aperture (NA) of an optical system
(e.g. an imaging system) is a measure for its angular
acceptance for incoming light.
Numerical aperture is the limit of the light at which
they are entering in to the objective

14. Light microscope

15. Condenser and Numerical aperture

16. Numerical aperture = n sin 
where
 is angle of light forming the numerical
aperture
n= Refractive index

17. REFRACTION AND REFRACTIVE INDEX
 Light microscopy uses glass (lens) for bending and focusing
the light.
 Refraction (bending) of light is the manifestation of different
light velocities in different materials.
 Refractive index of a material is therefore a measure of the
velocity of light in that material.
 The bending caused in the light beam when it enters from one
material into another is given by the Snell’s law

18. Refractive index
 Refractive index tells us how fast light travels in the material compared
to in a vacuum (or air)
 n= speed of light in a vacuum (or air) / speed of light in the material

19. Electromagnetic spectrum

20. Thank you