Laser Microscope

Aim: To find the average size of microbes in a water sample using laser microscope.

Apparatus: Water sample with microbe culture, syringe, laser source (wavelength = 635 nm), scale, retort stand, screen

Introduction:

A plastic syringe contains water sample with microbe culture. A water droplet is formed at the open end of the syringe when the piston of the syringe is gently pressed. A Laser beam is focused on the droplet. On the screen, we see a magnified image of the microbes present in the water droplet. Around the magnified image of the microbes, we observe a diffraction pattern. By studying this diffraction pattern, we will find their average size.

Schematic representation of the set-up

Fig.1 The photograph of the pattern obtained on the screen

Procedure:

1. From the photographs given below, generate the relevant data from the diffraction patterns.
2. Devise your procedure to generate the data with 1% uncertainty. Find the average size of microbes present in the water sample used here.

Observations:

Result:

The average size of microbes present in the given water sample is _______________