Hi Randall,

This sounds very intriguing, but it's frustrating that the cost of 
joining IOP is not
published on the web site and must be obtained by sending them an 
E-mail message!

I hate systems like that, because it's one more probable source of 
future junk mail.

Cheers,
John

At 04:54 AM 2/26/2008, you wrote:
>With the attention so frequently given to optical-type detectors, I 
>am surprised that nobody
>has yet (to my knowledge) mentioned what I believe to be the most 
>clever invention of them
>all.
>The great R. V. Jones, who is best known and quoted in seismology 
>for his work with
>capacitive sensors, while at Aberdeen invented a modified optical 
>lever that uses Ronchi
>rulings.  Ronchi is in this modern era largely unknown, but his 
>contributions in the field of
>figure-testing of optical components was of truly great 
>significance.  Those who want to
>study Jones' system can download the following paper:
>http://iopscience.iop.org/0950-7671/38/2/301/pdf
>What is most remarkable about the coarse gratings (Ronchi rulings) 
>used for this work is that
>they work with ordinary (non-monochromatic) light from an 
>incandescent bulb.  I have for
>about two decades demonstrated to students the physics of this 
>remakable system by means of a
>spherical mirror in which the white light bulb/grating combination 
>is situated at the center
>of curvature.
>     To those who are impressed by observing displacements as small 
> as a nanometer, consider
>the following:  In the 1960 paper referenced above, Jones claims a 
>resolution of 0.1 nrad!
>It should be noted that this device is not a simple (standard) 
>optical lever where one
>typically is limited to tenths of a microradian;  Jones combined 
>Ronchi rulings with the
>optical lever to produce a whole new concept--much better for 
>seismic purposes, if anybody
>wants to try it.  In my case--so much of interest, limited time left 
>to pursue them!
>
>


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