ek 5 study we energy and Introduction Lasers are common technology used in a wide range of applications. A laser pulse is composed of a packet of photons all wiff a similar wavelength and frequency traveling at the speed of light The energy of each photon in due laser pulse is gtven by the following formula: Epkotmn = where h = 6 (calle d Planck* s Constant) In this case study, you will employ this formula, the speed oflight: and the concept of power to determine the properties of a specific laser. To get stalted, review the following example : Example A laser IS used in eye surgery. The laser wavelength is 514.5 nm Q) and Pulse Power IS P Watts m each laser pulse. Durmg the surgery the laser is pulsed for a time duration of SO During that pulse how many photons are produced? The laser wavelength is given. We want to find the frequency first c = Af Where c ts speed of light & f ts frequency. W k 5 stu d y energy and Now that you 've reviewed the example above, it is time to explore the properties ofa different laser Review the case below and answer the questions ffat follow. Please show all your work below for fill credit A surgical laser with a waveleng of 810 nm delivers 250 of power on the retina of a patient It produces a I msec duration pulse of light I What is the energy of each photon? (300/0) 2. What is the laser energy per pulse? (30%) How many photons does it produce? (30%) 4 _ In what region of the spectrum is tllis light? (10%) 275,000 J 3.7X10" (Hz) (6.63 x 1044) (3.7 x x J watts x 1.5ms (1.5 x 10 = 375,000 Joules 9.7 Photons f 5.8 x 1014s-I(Hz) The energy of each photon. = = (6.63 x 1044) (5.8 x 1014s-l(Hz)) =3.87 x J Energy of the pulse is by product of the pulse power and the time Jou2'(sox10 sec ) = .075 Joules so = Pt = 1.5 watts X 50ms = 13 Then the energy of each pulse is 2075 Joules. The number photons n is: 1.94 X is the number ofphotons produced in this pulse. Exercise