[General] Verification of Light Interactions

[robert hudgins]

Dear Chip,

   To have our SPIE  presentation, with its data, receive a broad, non-specific and vocal rejection from many attendees was personally confusing.  From our perspective, those results (and ideas) had been thoroughly tested, retested and reconciled with current literature. The openness you indicated by your intent to try replicating some our results felt refreshing.

What follows are some pointers about possible ways to work-around the problem of short wavelength intervals:

The standing wave frequency is 1/2 the wave length of the light used.  Consequently, some method of expansion is usually required for clear visualization of a standing wave pattern.   Many investigators use Otto Wiener's 1890 method or some variation.  Recently, a simplified classroom demonstration procedure was published.

http://scitation.aip.org/content/aapt/journal/ajp/77/8/10.1119/1.3027506

Standing waves of light in the form of optical lattices are currently a workhorse for manipulating ultra-cold bosons and fermions.  The atoms are trapped between the oscillating potentials. 













 For a review:  Bloch, I., "Ultracold quantum gases in optical lattices", Nature Physics 1, 23-30
(2005)





Another important standing wave/interference demonstration is the 1837 Lloyd's mirror experiment.  













Tischmarsh, T. S.,   “Lloyds single-mirror interference fringes,”
Proc Phys Soc 53, 391-403, (1941)





For our study we used a precision 15 X 5cm mirror.  A laser beam was reflected a shallow angle and the resulting interference pattern was examined after expanding its image.  This was accomplished with a convex mirror placed near the end of the reflection zone.  We did this experiment to demonstrate that a mirror reflection would substitute for one of the beams in a two crossing-beam interference pattern, and that the null zones in the crossed-beam interference behaved as mirror--like reflection zones.   

The set-up we use for our interference studies is very simple.   It requires only two components; a laser and a variable density filter.  The variable density filter becomes a beam splitter when the laser beam is reflected from both the front and the back (partially mirrored) surface.  Adjusting the relative intensities and phases of the emerging beams is accomplished by changing the reflection angle and the point where the beam strikes the splitter.  Proper adjustment should give two clearly separated, and independent beams.   This system gives clear, unambiguous results.

We began our pursuit as a search for the "cancelled" energy of light interference.  It was quickly obvious that all the light energy in the beams emerging from the beam splitter was detectable in the interference patterns, that formed at some distance from the splitter.   (Well after the beams had merged.)  Although interference confined the light to a smaller area, (compressed the light) we found no evidence of "cancelled" light waves (energy) or of photodetector limitations.       





















Hudgins, W. R., Meulenberg, A., Ramadass, S.,
“Evidence for unmediated momentum transfer between light waves,” Paper 8121-39,
Proc. SPIE 8121 (2011) Hudgins, W., R., A. Meulenberg, A., Penland, R. F.
“Mechanism of wave interaction during interference,” SPIE (2013) Paper 8832-7, in The
Nature of Light: What are Photons? 



  

Please let us know if you were successful, or not, with your testing.

Bob     




 		 	   		  
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