basic concepts of microscope

1. JIWAJI UNIVERSITY
SUBMITTED BY :
MANISHA SINGHAI
M.Sc. MHG 4TH SEM
CENTRE FOR GENOMICS
TOPIC : LIGHT MICROSCOPY

2. CONTENTS
• INTRODUCTION
• COMPONENTS OF LIGHT MICROSCOPY
• PRINCIPLE AND FUNCTION
• TYPES OF LIGHT MICROSCOPY
• REFERENCES

3. INTRODUCTION
• Light microscope often referred to as the optical microscope .it is an type
of microscope which uses visible light and a system of lens to magnify
image of small samples.
• It is an oldest design of microscope and possibly designed in their present
compound forming in the 17th century
Bio science .com

4. • Historically light microscope where easy to develop and are popular
because they use visible light so that sample may be directly observed by
eye
• A light microscope work on a lot like a refracting telescope except that the
object is very close to objective lens .
• Light microscope may simple or compound

5. Components of light microscope
• There is a body tube with an ocular or eye piece mounted at its upper end
& objective lens of different magnifying power
• Arms hold the movable body tube in front & is fixed in the base
• There are two focusing knob one for coarse focusing & other for the fine
focusing
• Object stage is rigid platform with an aperture through which light rays
can pass
• Light sources a reflecting mirror is placed below the stage which reflect
sun light on objective
• Mechanical stage is equipped with scale which permit accurate mechanical
positioning of slide
• Lens system the compound microscope comprises three kind of lenses

6. • The condenser is located below the stage & above the mirror . It collected
and focus the light rays into the plane of objects that take no part in image
formation
• The objective this are mounted on revolving nose pieces. 10X ,40X, &
100X are magnification of objective lenses . It collect light rays from object
& from magnified real images.
• Ocular of eye piece at top of body tube . A monocular microscope consist
of one ocular ,while binocular microscope have two ocular of similar
magnification generally , ocular with 5x, 12.5x &15x lenses are available
the ocular magnifies the image formed by objective

7. Microscope international.com

8. Working principle
• Illumination light microscope with built in illumination use kohler or
kohler type illumination . In this type of illumination there are adjustable
collector lens in front of the source of light
• Image formation occurs in two stages the first is formed by the objective .
It is real , invert and magnified. The second is formed by ocular . It is
virtual inverted & more magnified
• Three principle is main for microscope
A. Magnification
B. Resolution
C. contrast
Slide share.com

9. Types of light microscope
 Bright field microscope
 Phase contrast microscope
 Dark field microscope

10. Bright field microscope
• Brightfield microscopy is the most elementary form of microscope
illumination techniques and is generally used with compound microscope
• The name “brightfield” is derived from the fact that the specimen is dark
and contrasted by the surrounding bright viewing field . Simple light
microscope sometimes referred to as brightfield microscopes.

11. Medical dictionary .com

12. Phase contrast microscope
• The basic principle to making phase changes visible in phase- contrast
microscopy is to separate the illuminating ( background light) from the
specimen – scattered light and to manipulate these differently .
• Ring shaped illuminating light that passes the condenser annulus is focused
on the specimen by the condenser . some of the illuminating light is
scattered by the specimen and form the background light
• When observing unstained biological specimen , the scattered light weak
and typically phase- shifted by -90 relative to background light . This leads
to foreground and background having nearly same intensity , resulting in
low image contrast

13. Microbes notes.com

14. Dark field microscope
• A dark field microscope is used to examine live microorganism that either
invisible in the ordinary light microscope , cant be stained by standard
methods , or are so distorted by staining that their characteristics then
cannot be identified
• Instead of normal condenser , dark field microscope uses a dark field
condenser that contain a opaque disc .
• Disc blocks light that would enter the lens directly , only the light is
reflected off the specimen would enter the objective lens .

15. Serc.carlton.edu

16. Advantages
• Brightfield microscope –it is very simple to use with fewer
adjustments needed to be made to view specimens
• Some specimens can be viewed without staining and optics used in the
brightfield technique don’t alter the color of specimen.
• Phase contrast microscope- unstained paraffin, resin & frozen
sections.
• Living cells and their behavior
• Cell organelles ,esp. mitochondria
• Capsules of microorganism

17. • Dark field microscopy- it allows researcher to identify various
different molecules in targeted specimen.
• a dark field microscope is ideal for viewing objects that are unstained,
transparent and absorbs little or no light
• It is more useful in examining external details, such as outlines , edges ,
grain boundaries and surface defects
• Use of this microscopy to study about marines organism such as algae and
plankton , insects, thin polymers and some ceramics .

18. REFERENCES
• The principle and practice of light microscopy( Cambridge university
press)
• Classification of microscope( JR BLUEFORD)