The document discusses three types of microscopes: bright field, dark field, and phase contrast. A bright field microscope uses a condenser and objective lenses to illuminate specimens from below and view them with high magnification. Dark field microscopy uses a special condenser to prevent direct illumination, making the background dark and allowing specimens to be seen by light they scatter. Phase contrast microscopy was developed by Frits Zernike and uses special lenses to increase contrast by converting phase differences in light waves to amplitude differences, allowing unstained living cells to be viewed.
2. BRIGHT FIELD MICROSCOPE :
Compound student microscope
Mechanical parts :
Base – horse shoe shaped
Pillar
Inclination joint arm or limb
Stage – stage clip to fix slide
Sub stage – carries condenser
Body tube
Coarse and Fine adjustments
Revolving nose piece
3. Optical parts :
Objective – Low power(10x), High dry(45x), Oil immersion(100x)
Eye piece – Monocular, Binocular
Condenser – condense light cone shape, control light intensity,
iris diaphragm to regulate light
Mirror – lens with one plane and one concave surface
attached to pillar
focus in three directions
6. DARK FIELD MICROSCOPE :
Specimen (illuminated), Background (dark)
Special condenser – prevents parallel and oblique rays to enter objective,
thus making the field dark
Absence of specimen – dark
Presence of specimen – scatter rays and specimen gets illuminated
Maximum magnification – 1500x
Resolution – 0.1 – 0.2 m
Used for finding cells in suspension
8. PHASE CONTRAST MICROSCOPE :
Discovered by Frits Zernike in 1930’s
Special condenser, objective and magnifier
Change in phase increase the contrast of image
Used to study unstained / living cells
Resolving power – 0.1 – 0.2 m