says about microscopy techniques using light as the illumination source

1. LIGHT MICROSCOPY NIDHILANGELO M M

2. INTRODUCTION
Light microscopy is based on the properties of light.
Different types of microscopes include
- Simple microscope or stereomicroscope
- Compound microscope
- Phase contrast microscope
- Polarizing microscope
- Confocal microscope

3. SIMPLE
MICROSCOPE
Also known as stereomicroscope.
It is a single lens or closely placed set of
lens is used to magnify the object.

4. COMPOUND MICROSCOPE
It can be of two types
- Bright field microscopy :- Utilize bright light to view microscopic
objects.
- Dark field microscopy :- Utilize dark light to view microscopic
objects.

6. COMPONENTS OF COMPOUND
MICROSCOPE
1. Light source
2. Condensers
3. Objective stage
4. Objective
5. Nose piece
6. Body tube
7. Eye piece

7. COMPONENTS CONT……
1. Light source :- Sun light, oil lamps, simple pearl lamps or high intensity
lamp were used.Modern light microscope contain built in light source.
Halogen bulbs are also used.
2. Condenser lens :- Used to focus the available light into the plane of object.
3. Objective stage :- The stage supports glass slide bearing specimen.
4. Objective :- Objective lens used to magnify the images of objects to be
viewed.
5. Nose piece :- Also known as turret. The upper part of a compound
microscope that holds the objective lens.
6. Body tube :- Three main forms are available monocular,binocular and the
combined photo ocular.
7. Eye piece :- It is basically a simple microscope to observe image formed by
the objective. The most commonly used ones are huygenian (achromatic
objective) and compensating eyepiece (apochromatic objective).

8. DARK FIELD
MICROSCOPE
An opaque disc is
placed underneath the
condenser lens, so that
only light that is
scattered by objects on
the slide can reach the
eye.

9. APPLICATIONS
- To observe objects and details at a cellular level to learn more
about the building block of all organisms.
- Microscopes are also used to observe real time movement in cells
and organisms.
- Used to study diseases like cancer and AIDs to help diagnosis the
disease in patients.
- Also used when studying light and optics to learn how light refracts
through converging lenses and how a combination of different lenses
with varying focal lengths affects the properties of the images.
- Used in forensics.
- Also used in mineralogy.

10. PHASE CONTRAST
MICROSCOPY
Uses two characteristics of
light , diffraction and
interference , specimens
based on brightness.
It requires additional
specialization structure
annular diaphragm and
phase contrast ring.

11. APPLICATION
- Most commonly used to provide contrast of transparent specimens
such as living cells or small organelles.
- Useful in observing cells cultured in vitro during mitosis.
- Phase contrast microscope enables visualization of internal cellular
component.
- It is used in examination of growth , dynamics and behavior of a
wide variety of living cells in cell culture.
- It is applied for equipment from the study of the living biological
specimens . Medical applications , study of live blood cells and other
biologicaland science applications.
- Used in diagnosis of tumour cells.

12. POLARIZING
MICROSCOPE
It is the microscope that
uses polarized light for
looking at specimens.
Was initially made for
studying rocks and
minerals.

13. COMPONENTS OF POLARIZED
MICROSCOPE
1. Nicol prims :- A polarizer made from calcite.
2. Polaroid discs :- Polaroid (glass or celluloid) covered
discs with the ability to polarize light.
3. Analyzer :- Is the upper polarizer which is placed
between the objective and eyepiece.
4. Polarizing objective :- Is designed and manufactured to
have low turbulence by refraction in the polarizing state on
the lens surface.
5. Polarizing condenser :- It has a built in rotatable
polarizer, top lens out construction and strain free optical
system.
6. Polarizing rotating stage

14. APPLICATIONS
- To view artifacts like formalin pigments, starch etc.
- To view crystals like talc, urate, pyrophosphate,
silica etc.
- To view lipids.
- To view bone structure.
- Also to view muscle striations , charcot etc.

15. CONFOCAL
It is an optical imaging
technique for increasing
optical resolution and
contrast of a micrograph by
means of using a spatial
pinhole to block out of
focus light in image
formation.
The working principle were
- Point by point
illumination of specimen.

16. MAIN COMPONENTS
1. LASER :- Light Amplification by Stimulated Emission
of Radiation are used because they are an intense
whereat monochromatic source of light.
2. Photomultiplier :- Is useful for light detection of
very weak sinals.
3. Filters :- It will increase contrast , blocking ambient
light , removing harmfull UV or IR light or for
selectively transmitting only wanted wavelength.

17. APPLICATIONS
1. Confocal microscopy allows analysis of fluorescent
labelled thick specimens without physical sectioning.
2. 3D reconstruction of specimen.
3. Improved resolution.
4. It is possible to detect more colour.