Husserl talk

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Shows a connection between Husserl's phenomenology and problem solving in optical design

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Husserl talk

  1. 1. Optical Design and Husserl’s Phenomenology David Shafer David Shafer Optical Design USA
  2. 2. Founder of Phenomenology <ul><li>PhD in mathematics </li></ul><ul><li>Became professor of </li></ul><ul><li>philosophy at University of </li></ul><ul><li>Gottingen, later at Freiburg </li></ul><ul><li>One of the most influential </li></ul><ul><li>philosophers of the 20 th </li></ul><ul><li>century </li></ul>
  3. 3. Husserl’s insights <ul><li>Perception depends on what is out there (reality)+ what we bring to it </li></ul><ul><li>With practice we can see what we have added, like hidden assumptions and interpretations </li></ul><ul><li>If subtracted off, then we are left with reality </li></ul>
  4. 4. The Goal <ul><li>Remove from an optical design problem hidden assumptions, false choice options, unnecessary constraints, etc. </li></ul><ul><li>Result = the true problem </li></ul>Very hard to do, because we see things that are not really there. It is just human nature.
  5. 5. An example - we easily see faces that are not there
  6. 6. It is very hard to resist this
  7. 8. But seeing face depends on orientation
  8. 9. Even animals make these perceptual overlays on reality <ul><li>A bird outline is moved across the sky </li></ul><ul><li>above baby geese. </li></ul><ul><li>When moving in one direction it looks like an adult goose </li></ul><ul><li>When moved in the opposite direction it looks like a hawk, and represents danger </li></ul><ul><li>It is the exact same shape, only the motion is different </li></ul>
  9. 10. Baby geese and danger Hawk Goose
  10. 11. How to reduce what we bring to a design problem (so as to discover what the real problem is) <ul><li>Change coordinate system or orientation of diagrams </li></ul><ul><li>Question hidden assumptions in any diagrams/drawings </li></ul><ul><li>Restate design problem in terms of goals, without stating the means to those goals. </li></ul><ul><li>Try to identify limited choice assumptions </li></ul>
  11. 12. <ul><li>Change coordinate system or orientation of diagrams </li></ul>Try to quickly say the colors of the letters of these words Then try again with them turned upside down Being able to read is a handicap here, so turn upside down
  12. 13. Copying (forging) a signature Herman Darvick You will tend to write in your own style – hard to avoid Only copy shapes, not letters Upside down To be copied
  13. 14. Confusing – what is this? Good – have an open mind about what you are seeing
  14. 15. Rotated picture Here we use familiar sights to interpret and understand the picture, But the picture has not changed. Our perception has changed Bad – we see much more, like intended use of the water, than is really there. It is just water – the swimming use is what we bring to it.
  15. 16. This view is more reality-based
  16. 17. Optical design goal <ul><li>Minimize what I bring to a problem </li></ul><ul><li>Look for hidden assumptions </li></ul><ul><li>Question all assumptions </li></ul><ul><li>Look for alternate choices </li></ul><ul><li>Be smart in solving the problem but “stupid” </li></ul><ul><li>in understanding it (i.e., don’t assume anything) </li></ul>
  17. 18. Dec 2007 / Slide Laser Fusion Questioning assumptions in a drawing
  18. 19. Highly aspheric lens Conic mirror Target pellet Early Laser Fusion Experiments Laser input Laser input
  19. 20. Dec 2007 / Slide Target pellet filled with tritium gas
  20. 21. Dec 2007 / Slide Target ignition at 100 million degrees
  21. 22. Conventional lens picture from textbook – light stops at focal point : film, detectors, etc.
  22. 23. Less common view = light keeps on going
  23. 24. Insight <ul><li>Target pellet is not part of optical system </li></ul><ul><li>Hidden assumption – rays are stopped by </li></ul><ul><li>target pellet, as system drawing shows </li></ul><ul><li>New Idea </li></ul><ul><li>Remove target pellet and only consider the optics. What happens then? </li></ul><ul><li>Then rays hit two mirrors instead of one </li></ul><ul><li>Consider a new design with two reflections </li></ul>
  24. 25. Only one ray shown, with target removed Rays sees two reflections, then leaves system
  25. 26. Only one half is traced here Now is aspheric, not conic New design, with two reflections before hitting target
  26. 27. Slower speed lens, much less asphericity, better ghost images, less lens heating, lower cost Original design New, better design
  27. 28. Further insight <ul><li>New hidden assumption - rays are stopped by </li></ul><ul><li>target after two reflections </li></ul><ul><li>Consider three reflection design </li></ul><ul><li>Result is even better system – all reflective, </li></ul><ul><li>no lens heating or ghost images </li></ul>
  28. 29. Simple telescope example Hole in mirror image
  29. 30. Insight <ul><li>Hole in mirror is not part of optics </li></ul><ul><li>Don’t assume a hole </li></ul><ul><li>Consequence – light reflects again at primary mirror </li></ul><ul><li>Explore opportunities to use that </li></ul>
  30. 31. Corrected for spherical aberration, coma, and astigmatism Final image First image
  31. 32. Path of a single ray Image
  32. 33. Corrected for spherical aberration, coma, and astigmatism (with two conic mirrors) Final image first image
  33. 34. Further insight <ul><li>If no hole in secondary mirror then get another reflection there. </li></ul><ul><li>don’t assume holes in mirrors </li></ul><ul><li>Investigate multiple reflection systems with just two mirrors </li></ul>
  34. 35. Two spheres, four reflections 3.33X Corrected for spherical aberration, coma, astigmatism, and Petzval curvature, with just two spheres.
  35. 36. / Slide Stereo paintings viewer
  36. 37. “ natural ” way to think – right eye sees image on right, left eye sees image on left “ Unnatural” way to think Equally useful alternate arrangement – but must switch paintings positions
  37. 38. Dec 2007 / Slide Effect on viewer of reverse stereo
  38. 39. Try to identify assumptions about limited choices
  39. 40. New type of stereo viewer Arrangement when not in use and folded up Works both ways, but having crossed lines of sight gives more room for eyes and larger field of view. Crossed lines of sight Ray path does not give usual color or distortion of prisms
  40. 41. Door Hole Viewer
  41. 42. Eye pupil Outside of door Door viewer optics – strong negative power Extremely wide angle rays Inside of door
  42. 43. Eye outside door looking in Can’t see inside because of extreme vignetting – rays miss the eye Can only see a very narrow angle through the optics Optics pupil is inside the system, where eye can’t get at it
  43. 44. Used by police and firemen. Also spies and voyeurs But there is a sneaky way around this!
  44. 45. Actual system Door hole viewer eye Peephole Reverse Viewer Door width
  45. 46. Binocular or monocular optics Unfolded light path Prisms equivalent eye eye
  46. 47. <ul><li>Hidden assumption about binoculars/monoculars </li></ul><ul><li>We are supposed to look through one end but not the other one </li></ul><ul><li>But that is what we, humans, bring to the optical device – it is not part of it </li></ul><ul><li>Insight </li></ul><ul><li>You can look through it backwards too and maybe find a new use for it. </li></ul>
  47. 48. Optics used backwards eye eye Relayed image of eye
  48. 49. eye Move these optics towards right and match up pupils That effectively then puts eye completely to right of the door viewer, and inside the room Relayed image of eye Door width
  49. 50. <ul><li>Next - </li></ul><ul><li>Another example of questioning hidden assumptions in a drawing or diagram </li></ul><ul><li>Results - a new type of perfect optical </li></ul><ul><li>system, with no aberrations </li></ul>
  50. 51. Maxwell’s Fish Eye (1854) a gradient index ball Every point on surface of ball is imaged perfectly to opposite point on ball Ray paths inside ball are arcs of circles n = 3.0 at center, 1.5 at outer rim
  51. 52. Hidden assumption in this drawing Rays stop at point #2 But in reality they would total internal reflect there and continue on Point #1 Point #2
  52. 53. Actual ray path Reflects here at surface of ball Starts here Returns here, reflects again, and goes around forever
  53. 54. New Idea <ul><li>Cut ball in half and put reflecting coating on </li></ul><ul><li>outside surface </li></ul>It can be proven that then every point on flat diameter surface is imaged perfectly back onto that same surface <ul><li>First new perfect optical system in over 50 years </li></ul><ul><li>The only perfect system that forms a flat real image of a flat real object </li></ul>
  54. 55. Known perfect optical systems <ul><li>Flat mirror flat and real flat and virtual </li></ul><ul><li>Aplanatic surface curved and real curved and virtual </li></ul><ul><li>Maxwell fish eye curved and real curved and real </li></ul><ul><li>Luneberg lens collimated curved and real </li></ul><ul><li>New design flat and real flat and real </li></ul>Object image
  55. 56. How to reduce what we bring to a design problem <ul><li>Change coordinate system or orientation of diagrams </li></ul><ul><li>Question hidden assumptions in any diagrams/drawings </li></ul><ul><li>Restate design problem in terms of goals, without stating the means to those goals. </li></ul><ul><li>Try to identify limited choice assumptions </li></ul>

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