Husserl talk

Optical Design and Husserl’s Phenomenology David Shafer David Shafer Optical Design USA

Founder of Phenomenology PhD in mathematics Became professor of philosophy at University of Gottingen, later at Freiburg One of the most influential philosophers of the 20 th century

Husserl’s insights Perception depends on what is out there (reality)+ what we bring to it With practice we can see what we have added, like hidden assumptions and interpretations If subtracted off, then we are left with reality

The Goal Remove from an optical design problem hidden assumptions, false choice options, unnecessary constraints, etc. Result = the true problem Very hard to do, because we see things that are not really there. It is just human nature.

An example - we easily see faces that are not there

It is very hard to resist this

But seeing face depends on orientation

Even animals make these perceptual overlays on reality A bird outline is moved across the sky above baby geese. When moving in one direction it looks like an adult goose When moved in the opposite direction it looks like a hawk, and represents danger It is the exact same shape, only the motion is different

Baby geese and danger Hawk Goose

How to reduce what we bring to a design problem (so as to discover what the real problem is) Change coordinate system or orientation of diagrams Question hidden assumptions in any diagrams/drawings Restate design problem in terms of goals, without stating the means to those goals. Try to identify limited choice assumptions

Change coordinate system or orientation of diagrams 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

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

Confusing – what is this? Good – have an open mind about what you are seeing

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.

This view is more reality-based

Optical design goal Minimize what I bring to a problem Look for hidden assumptions Question all assumptions Look for alternate choices Be smart in solving the problem but “stupid” in understanding it (i.e., don’t assume anything)

Dec 2007 / Slide Laser Fusion Questioning assumptions in a drawing

Highly aspheric lens Conic mirror Target pellet Early Laser Fusion Experiments Laser input Laser input

Dec 2007 / Slide Target pellet filled with tritium gas

Dec 2007 / Slide Target ignition at 100 million degrees

Conventional lens picture from textbook – light stops at focal point : film, detectors, etc.

Less common view = light keeps on going

Insight Target pellet is not part of optical system Hidden assumption – rays are stopped by target pellet, as system drawing shows New Idea Remove target pellet and only consider the optics. What happens then? Then rays hit two mirrors instead of one Consider a new design with two reflections

Only one ray shown, with target removed Rays sees two reflections, then leaves system

Only one half is traced here Now is aspheric, not conic New design, with two reflections before hitting target

Slower speed lens, much less asphericity, better ghost images, less lens heating, lower cost Original design New, better design

Further insight New hidden assumption - rays are stopped by target after two reflections Consider three reflection design Result is even better system – all reflective, no lens heating or ghost images

Simple telescope example Hole in mirror image

Insight Hole in mirror is not part of optics Don’t assume a hole Consequence – light reflects again at primary mirror Explore opportunities to use that

Corrected for spherical aberration, coma, and astigmatism Final image First image

Corrected for spherical aberration, coma, and astigmatism (with two conic mirrors) Final image first image

Further insight If no hole in secondary mirror then get another reflection there. don’t assume holes in mirrors Investigate multiple reflection systems with just two mirrors

Two spheres, four reflections 3.33X Corrected for spherical aberration, coma, astigmatism, and Petzval curvature, with just two spheres.

/ Slide Stereo paintings viewer

“ 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

Dec 2007 / Slide Effect on viewer of reverse stereo

Try to identify assumptions about limited choices

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

Eye pupil Outside of door Door viewer optics – strong negative power Extremely wide angle rays Inside of door

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

Used by police and firemen. Also spies and voyeurs But there is a sneaky way around this!

Actual system Door hole viewer eye Peephole Reverse Viewer Door width

Binocular or monocular optics Unfolded light path Prisms equivalent eye eye

Hidden assumption about binoculars/monoculars We are supposed to look through one end but not the other one But that is what we, humans, bring to the optical device – it is not part of it Insight You can look through it backwards too and maybe find a new use for it.

Optics used backwards eye eye Relayed image of eye

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

Next - Another example of questioning hidden assumptions in a drawing or diagram Results - a new type of perfect optical system, with no aberrations

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

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

Actual ray path Reflects here at surface of ball Starts here Returns here, reflects again, and goes around forever

New Idea Cut ball in half and put reflecting coating on outside surface It can be proven that then every point on flat diameter surface is imaged perfectly back onto that same surface First new perfect optical system in over 50 years The only perfect system that forms a flat real image of a flat real object

Known perfect optical systems Flat mirror flat and real flat and virtual Aplanatic surface curved and real curved and virtual Maxwell fish eye curved and real curved and real Luneberg lens collimated curved and real New design flat and real flat and real Object image

How to reduce what we bring to a design problem Change coordinate system or orientation of diagrams Question hidden assumptions in any diagrams/drawings Restate design problem in terms of goals, without stating the means to those goals. Try to identify limited choice assumptions

Husserl talk

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Husserl talk