<HTML><HEAD> <META content="text/html; charset=Windows-1252" http-equiv=Content-Type></HEAD> <BODY dir=ltr> <DIV dir=ltr> <DIV style="FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: 12pt"> <DIV>Andy,</DIV> <DIV> </DIV> <DIV>If the phosphor simply absorbed the photons that hit it, and did not re-emit them, the brightness of the hole would be the same as the brightness of the phosphor surface – even though the emittance of the hole is much smaller than the total emittance of the phosphor surface. </DIV> <DIV> </DIV> <DIV>[This is the usual version of the brightness theorem.]</DIV> <DIV> </DIV> <DIV>---------------------------------------------</DIV> <DIV>What is special about the aperture lamp is the the photons that do not immediately go out the hole are not wasted, but eventually get out – and into the same transverse phase space as the photons that got out on the first try.</DIV> <DIV> </DIV> <DIV>In this case, more photons/sec emerge from the hole than we expected from a more ordinary lamp.</DIV> <DIV> </DIV> <DIV>And, the brightness is thereby increased.</DIV> <DIV> </DIV> <DIV>------------------------------</DIV> <DIV>When multiple bunches are injected into a storage ring, we don’t succeed in putting them into the same region of phase space.  Rather, they are put into adjacent regions (phase-space painting).   This increases the number of particles in the circulating bunch, but the brightness of that bunch is not increased.</DIV> <DIV> </DIV> <DIV>Whereas, the the aperture lamp, a photon goes into the same region of phase space not matter how many tries it takes to get there.</DIV> <DIV> </DIV> <DIV>--Kirk</DIV> <DIV> </DIV> <DIV>PS  Your comments have sharpened my thinking about this interesting process.   As a result, I’ve updated my note, with new footnotes 6, 9 and 25.</DIV> <DIV><A title=http://puhep1.princeton.edu/~mcdonald/examples/lamp.pdf href="http://puhep1.princeton.edu/~mcdonald/examples/lamp.pdf">http://puhep1.princeton.edu/~mcdonald/examples/lamp.pdf</A></DIV> <DIV> </DIV> <DIV>Thanks for prompting me in this way.</DIV> <DIV> </DIV> <DIV> </DIV> <DIV> </DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"> <DIV style="FONT: 10pt tahoma"> <DIV><FONT size=3 face=Calibri>                                </FONT></DIV> <DIV style="BACKGROUND: #f5f5f5"> <DIV style="font-color: black"><B>From:</B> <A title=amsessler@lbl.gov href="mailto:amsessler@lbl.gov">Andrew Sessler</A> </DIV> <DIV><B>Sent:</B> Thursday, December 20, 2012 12:51 PM</DIV> <DIV><B>To:</B> <A title=kirkmcd@Princeton.EDU href="mailto:kirkmcd@Princeton.EDU">Kirk T McDonald</A> </DIV> <DIV><B>Cc:</B> <A title=MAP-l@lists.bnl.gov href="mailto:MAP-l@lists.bnl.gov">MAP-l@lists.bnl.gov</A> </DIV> <DIV><B>Subject:</B> Re: [MAP] Light recycling; Piccione lip</DIV></DIV></DIV> <DIV> </DIV></DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"> <DIV dir=ltr> <DIV> <DIV> <DIV> <DIV>Thursday<BR></DIV>Dear Kirk,<BR><BR></DIV>I think I would say it differently and I would appreciate your comment: "Wrong!, Okay, Partially."<BR><BR></DIV>The photon number doesn't increase at each reflection, so the only effect is that the photon is bounced back and forth until it hits the hole and gets out. So, the effect is simply reducing the emittance from 4 pi (the whole sphere) to the area of the hole. Even simple to calculate the amplification. So, my view is not a re-using of photons, but a change in desired emittance.<BR><BR></DIV>Andy<BR></DIV> <DIV class=gmail_extra><BR><BR> <DIV class=gmail_quote>On Wed, Dec 19, 2012 at 8:36 PM, Kirk T McDonald <SPAN dir=ltr><<A href="mailto:kirkmcd@princeton.edu" target=_blank>kirkmcd@princeton.edu</A>></SPAN> wrote:<BR> <BLOCKQUOTE style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class=gmail_quote> <DIV style="WORD-WRAP: break-word" dir=ltr> <DIV dir=ltr> <DIV style="FONT-FAMILY: 'Arial'; FONT-SIZE: 10pt"> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>Folks,</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>I have become fortuitously aware of an old trick in the lamp industry that is now sometimes called “light recycling” – with the goal of enhancing the optical brightness of light sources.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>Remember, brightness = power / area in transverse phase space</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>(although the opticians don’t generally say it this way, perhaps using the buzzword “etendue” instead of “area in transverse phase space”)<BR></FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>In our project, we try to increase the brightness by “cooling”/shrinking the area in transverse phase space.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>The opticians’ trick is to “recycle” the light so that one photon gets counted many times in the same area in phase space, effectively increasing the power, while leave the emittance the same.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>The historical way of doing this (dating back at least to 1936) involves a cylindrical cavity lined with a phosphor (i.e., a fluorescent lamp) with a small slit in the phosphor to let light out.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>A photon has only a small probability P to escape out the slit directly after being emitted by the phosphor.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>Generally, the photon hits another region of the phosphor, is absorbed, and then re-emitted.  [The cavity can be lined with a reflector to assist in this process.]</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>On average, the photon bounces around N = 1 / P times before it escapes through the slit.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>Hence, the steady-state emission of photons by the phosphor surface is N times greater than if the photons flew away on their first emission – as holds for an ordinary fluorescent lamp.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>The net effect is that the light coming out of the slit is N times brighter than the light from an ordinary fluorescent bulb of the same output power.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>The brightness has been enhanced N-fold (with no emittance reduction) to the extent that the absorption and re-emission involves no losses.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>[I think the lamps in Xerox machines and scanners are of this type.]</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>I’ve written up a pedagogic note on this:</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><A title=http://puhep1.princeton.edu/~mcdonald/examples/lamp.pdf href="http://puhep1.princeton.edu/~mcdonald/examples/lamp.pdf" target=_blank>http://puhep1.princeton.edu/~mcdonald/examples/lamp.pdf</A></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>--------------------------------------</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>This trick seems different from what we do to enhance the brightness of particle beams.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>However, a comment by Fred Mills, dated 9/98, near the bottom of my web page</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial><A title=http://puhep1.princeton.edu/~mcdonald/mumu/physics/ href="http://puhep1.princeton.edu/~mcdonald/mumu/physics/" target=_blank>http://puhep1.princeton.edu/~mcdonald/mumu/physics/</A></FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>has me wondering if part of the effect of the “Piccione lip” seen on p. 4 of</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><A title=http://puhep1.princeton.edu/~mcdonald/mumu/physics/lichtenberg_mura-110.pdf href="http://puhep1.princeton.edu/~mcdonald/mumu/physics/lichtenberg_mura-110.pdf" target=_blank>http://puhep1.princeton.edu/~mcdonald/mumu/physics/lichtenberg_mura-110.pdf</A><FONT face=Arial> </FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>was to use multiple scattering in the “lip” to kick some particles into a desired area of phase space.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>That is, perhaps we can say that ionization cooling also includes a small effect equivalent to the opticians’ trick of “light recycling”.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>What do you think?</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>--Kirk</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>PS  The opticians are after big game = use of such tricks to make better solar energy concentrators for photovoltaic energy generation (or even just heating water).</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>In the past, such efforts have not involved brightness enhancement, but only clever rearrangement of light in phase space (as in Winston cones).</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>The next generation of brightness enhancement schemes uses materials with differing absorption and emission spectra to play additional “tricks”.   New engineered optical materials, called photonic band gap materials, could play a key role here.</FONT></DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial></FONT> </DIV></DIV> <DIV> <DIV style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT face=Arial>If these solar brightness-enhancement schemes pay off, they will be able to fund all of high energy physics....</FONT></DIV></DIV></DIV></DIV></DIV><BR>_______________________________________________<BR>MAP-l mailing list<BR><A href="mailto:MAP-l@lists.bnl.gov">MAP-l@lists.bnl.gov</A><BR><A href="https://lists.bnl.gov/mailman/listinfo/map-l" target=_blank>https://lists.bnl.gov/mailman/listinfo/map-l</A><BR><BR></BLOCKQUOTE></DIV> <DIV> </DIV></DIV></DIV></DIV></DIV></BODY></HTML>