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ENSC 460/894 Assignment 3: (Mar. 13, 2008 due Mar. 20, 2008) 1 The total power emitted by a CW laser in the TEM 00 mode is 5 W. If the focused spot 1/e 2 radius is 0.3 mm calculate the irradiance (power density) at the spot centre. (2 marks) 2 A pulsed Nd:Yag flashlamp pumped laser operates using a 100 μ F capacitor charged up to 2 KV for each pulse. The laser emits an approximately triangular pulse (see diagram in notes) of duration 1 msec and peak power 1 kW. Calculate the overall efficiency of the laser (assuming the Capacitor charging to be 100% efficient). 3 Calculate the refractive index difference per centimetre in lithium niobate (LiNbO 3 ) for an applied filed of 1000 V/cm. How long must a longitudinal Pockels cell be to cuase a phase change of 90 o between the fast and slow rays for a ruby laser light ( λ =694.3 nm)? 4. If the spot radius is 2 mm for a HeNe TEM 00 mode beam entering a lens of f=12.5 cm 3(a) Calculate the focused spot size.(3 marks) 3(b) Calculate the depth of focus to keep the spot size within 10% of the minimum value.(4 marks)
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This note was uploaded on 11/22/2010 for the course ENSC 470 taught by Professor Chapmann during the Spring '10 term at Simon Fraser.
- Spring '10