Physics

Unit 5 Case study

Laser Energy and Heat transfer

Below is a video that can be helpful:

(1) How a Laser Works - YouTube

A Laser is used to in eye surgery to weld a torn retina back into place. The laser wavelength is 514 nm and its Pulse Power is Ppulse = 1.5 Watts in each laser pulse. During the surgery the laser is pulsed for a time duration of 50 ms.

During that pulse how many photons are produced?

The laser wavelength is given. We want to find the frequency first

.

The energy of each photon;

=

The Energy of the pulse is defined by the product of the pulse power and the time so

Then energy of each pulse is ,075 Joules. The number photons n is:

17 is the number of photons produced in this pulse.

Given the results of this exercise

A neodymium YAG laser is used to repair glaucoma damage in another patient. Its wavelength = 1064 nm and produces an Energy of 4.1X10-3 joules.

1. What is the energy of each photon?

2. How many photons does it produce?

3. If this laser power is also 1.5 watts: How long is its pulse length?