The document discusses the dark field microscope, which was invented in 1830 by J.J. Lister. It describes how a dark field microscope works by placing an opaque disc under the condenser lens so that only light scattered by objects on the slide reaches the eye. This causes pigmented objects to appear in false colors. Some uses of the dark field microscope include examining unstained cells and samples in pond water or prepared slides, as well as determining mobility in cultures. While it produces beautiful images, it also has some disadvantages.

1. BY,
LOKESWARI B,
III BSC
BIOTECHNOLOGY
BON SECOURS COLLEGE FOR WOMEN,
THANJAVUR..

3.  INTRODUCTION
 PRINCIPLE
 EXAMPLES
 USES
 ADVANTAGES
 DISADVANTAGES

4. In 1830 J.J.Lister
(Joseph Lister)
invented the dark field
microscope.

6. To view a specimen in dark
field an opaque an opaque disc
is placed underneath the
condenser lens, so that only
light that is scattered by
objects on the slide can reach
pigmented objects are often
seen in false colors.

8. USED
FOR:
Initial examination
of suspension cells(
yeast, bacteria,
etc.,)
Initial survey and
observation at low
power of pond
water and samples.
Examination of
lightly stained
prepared slides.
Determination
of mobility in
cultures.

9. A dark field microscope is ideal
for viewing objects that are
unstained, transparent and absorb
little or no light.
These specimens often have
similar refractive indices as their
surroundings, making them hard to
distinguish with other illumination
techniques.

10. A dark field microscope
can result in beautiful and
amazing images; this
technique also comes with
a number of
disadvantages.