1. Trivia Question During the Strategic Defense Initiative (Star Wars Initiative) under President Ronald Reagan, which of the following futuristic weapons systems were developed? (a) Nuclear X-Ray Laser (b) Photon Torpedoes (c) Rail Gun (d) Brilliant Pebbles (e) Neutral Particle Beam

2. Trivia Question During the Strategic Defense Initiative (Star Wars Initiative) under President Ronald Reagan, which of the following futuristic weapons systems were developed? (a) Nuclear X-Ray Laser (b) Photon Torpedoes (c) Rail Gun (d) Brilliant Pebbles (e) Neutral Particle Beam All of them!

3. How do you ‘cheat’ nature and get around fundamental limitations of optics? Photon Torpedoes – Go nonlinear with high intensity laser pulses which self-focus in a medium to counteract diffraction. Embrace diffraction, but confine light to define spatial resolution BELOW diffraction limit.

4. Diffraction: Light does not like to be confined

5. Examples of Diffraction Knife edge Light passing by a sharp edge

6. Examples of Diffraction Waves passing through a small hole http://physics-animations.com/Physics/English/1wd_tmp.htm

7. Examples of Diffraction Focusing light with a lens Geometric Optics – Wavelength small compared to other dimensions. No Diffraction. Light focuses to a point. Wave Optics – Wavelength can be comparable to other dimensions. Diffraction MUST be considered. Light focuses to a minimum spot size. oo

8. Diffraction of light through an aperture

9. Sample Problem

10. Fresnel Diffraction Fraunhofer Limit

11. Error in Focusing

12. Simple demonstrations of Improved Focusing Squinting If you use corrective glasses, take off your glasses. Use your fingers to make a small aperture and look through the aperture. As the aperture gets small, the quality of the image improves! Better in focus. Pin hole camera – for a pin hole, depth of focus is large so that you can generate an image of a scene WITHOUT a lens.

13. 4-f imaging system

14. Spatial Filters

15. Image Quality with Wave Optics

16. Near-Field Imaging

17. THz Near-Field Imaging John F Federici et al 2002 Phys. Med. Biol. 47 3727

18. Hints for Problem 4.2-3