The document describes the components, working principle, and applications of a dark field microscope. A dark field microscope illuminates specimens from the side so that scattered light from the specimen is visible against a dark background. Key components are the light source, condenser lens, and objective lens. The microscope can be used to observe unstained living cells, bacteria, algae, and other microorganisms by revealing their internal structure in contrast to the dark background field. Applications include identifying bacteria, observing unstained cells and internal structures of microorganisms.

1. VISHAL RAJ K
HCA20M10
DARK FIELD MICROSCOPE

2. *CONTENT*
INTRODUCTION
DIAGRAM
WORKING PRINCIPLE
COMPONENTS
APPLICATION
ADVANTAGES & DISADVANTAGES
RELATED IMAGES

3. *INTRODUCTION*
Dark field microscope is a technique that
can be used for the observation of living,
unstained cells and microorganisms.
In this microscope, the specimen is brightly
illuminated while the background is dark.
The dark field microscope can reveal
considerable internal structure in
microorganisms.

4. *DIAGRAM*

5. *WORKING PRICIPLE*
A dark field microscope is arranged so that
the light source enters the microscope to
illuminate the specimen.
A special disc, called patch stop blocks
some light from the light source, leaving
an outer ring of illumination.
This is ideal for making objects with
refractive value similar to the back ground.

6. When light hits an object, rays are
scattered in all directions. The design
of dark field microscope is such that it
removes the dispersed light, so that
only scattered beams hit the sample.
The introduction of a condenser below
the stage ensures that these light rays
will hit the specimen at different
angles, rather than as a direct light
source towards the object.

7. Only scattered light started to enter the
objective lens and creates an image of
the specimen.
The result is a “cone of light” where
rays are diffracted, reflected and
refracted off the object ultimately,
allowing the individual to view a
specimen in dark field.

8. *COMPONENTS*
Dark field microscope consists of three key
components :~
Light source : enters the microscope and hits
the dark field path stop, which is a disc used
to block light from entering the condenser and
leaves a circular ring of illumination.
Condenser lens : collects outer ring of
illumination and focuses it on the sample.

9. Objective lens : light hits the sample, and
is transmitted or scattered from it.
Scattered light enters the objective lens,
whereas transmitted light is not collected
by the lens. The direct illumination block
assists in this step.

10. *APPLICATION*
The dark field microscope is used to
identify bacteria like thin and
distinctively shaped.
We can observe the living and
unstained cells using a dark field
microscope.
Considerable internal structure in
microorganisms can be revealed by the
dark field microscope.

11. A biological dark field microscope
used to identify algae.
A stereo dark field microscope used to
observe the shrimp or other
invertebrates.
It helps to characterize the embedded
nanomaterials in cells by combined
with hyperspectral imaging.

12. *ADVANTAGES*
No need to stain the specimen.
It is useful for those specimens that are
transparent and absorb little or no light.
Marine organisms such as algae,
plankton, insects, yeast and protozoa
can observe under a dark field
microscope.
It can be used for the research of live
bacteria and mounted cells and tissues.

13. *DISADVANTAGES*
Before use make sure slide, stage, nose
and light source are free from dust.
It cannot measure the specimen
accurately.
An intense amount of light is required
for a dark field microscope to work.

14. *RELATED IMAGES*
Blood cells Bacterial colony

15. Biomaterials
Nanoparticals in cancer cells

16. Cancer cells

17. THANK YOU