numerical aperture of a optical fibre.pptx

Optical fiber

1. name : k . abhinay Class : csm -c Roll no : 227Y1A66d1 Faculty : dR k . chaithanya kumar

2. AIM OF THE EXPERIMENT To determine the numerical aperture of an optical fiber.

3. ⦿ Numer i c a l a perture of an opti c al fibre is defined as the light gathering ability of the fibre. ⦿ Numer i c a l a perture al s o refers to the maximum angle at which the light incident on the fibre end is totally internally reflected and is properly transmitted along the fibre .

4. ⦿ An opti c al fiber ( o r opti c al fibre) is a flexible, transparent fiber made of glass ( silica ) or plastic, slightly thicker than a human hair. ⦿ It functions as a waveguide , or “ light pipe ”to transmit light between the two ends of the fiber.

5. It works on the principle of total internal reflection.

6. ⦿ Low T ran s mi s si o n Loss and W ide Bandwidth ⦿ I m mu n ity a n d Int e rfer e n c e ⦿ Sm a ll S i ze and W ei g hts ⦿ Sign a l Se c urity ⦿ El e ctri c al I s ol a tion ⦿ Abunda n t Raw M a teri a l ⦿ Le s s Exp e ns i ve

7. ⦿ An opti c al fibre c a ble ⦿ Optic a l fibre train e r board ⦿ Scr e en ⦿ con n e c ting wires

8. ⦿ Fib e r Optics T rain e r Model is designed to learn the basics of fiber Optics. ⦿ A large number of experiments.

9. ⦿ Make all the connections . ⦿ Connect one end of the optical fibre cable to the optical fibre trainer and other end to the numerical aperture jig. ⦿ Hold the white screen with four concentric circles (10, 15, 20 and 25 mm diameter) vertically at a suitable distance to make the red spot emitted from the optical fibre coincide with the 10 cm circle. Note that the circumference of the spot (outermost) must coincide with the circle.

10. ⦿ Record L, the distance of the screen from the fibre end and note the diameter (W) of the spot. ⦿ Compute the numerical aperture (NA) of the optical fibre by using the formula ⦿ NA = Sin θ =W/(4L2+W2)1/2 , ⦿ where θ is called as the acceptance angle is the maximum angle of incidence at the input end of the optical fibre so that he optical ray can just propagate within the optical fibre. ⦿ Tabulate the reading and repeat the experiment for 15 mm, 20 mm and 25 mm diameter too.

11. S.No LENGTH(mm ) DI A METER OF THE SPO T (m m ) N U ME R IC A L APERTUER( NA) A C C EP T A N C E ANGLE( DEGREE) 1 9 10 0.4 23.5 2 14 15 0.4 23.5 3 19 20 0.4 23.5 4 24 25 0.4 23.5

12. ⦿ Numerical aperture of optical fibre is 0.4mm.