Unformatted text preview: 4. If the spot radius is 1.5 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) 5 For a GaAs laser diode the laser emission area is 1 micron thick by 50 microns wide. Calculate the divergence angle in the vertical and horizontal direction. What is the Rayleigh range for each direction, (8 marks) 6 Assume a single layer antireflection coating is to be deposited on long IR ZnSe lens (n=2.4) for a wavelength of a CO 2 laser (10.4 microns). (a) What is the minimum thickness for this coating (3 marks) (b) What is the next smallest thickness that will give an AR coating. (2 marks)...
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- Spring '10
- Light-emitting diode, Gallium arsenide, MAXIMUM POSSIBLE EFFICIENCY, Yag energy level