One way glass?

[oklahoman]

<p>I saw an article about a proposed method for concentrating solar energy for solar cells, andit used what looked like a wedge shaped piece of plastic with a coating that allowed light in but would not let it out.</p><p>Is there any physical phenomina that would allow this to happen, or is this a scam?</p>http://cleantechnica.com/2008/09/04/new-concentrated-solar-tech-simple-cheap-and-efficient/<p>&nbsp;</p> <div class="Discussion_UserSignature"> </div>

 

[emperor_of_localgroup]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I saw an article about a proposed method for concentrating solar energy for solar cells, andit used what looked like a wedge shaped piece of plastic with a coating that allowed light in but would not let it out.Is there any physical phenomina that would allow this to happen, or is this a scam?http://cleantechnica.com/2008/09/04/new-concentrated-solar-tech-simple-cheap-and-efficient/ <br /> Posted by oklahoman</DIV><br /><font size="2">Thanks for the link. The link led me to Live Science and&nbsp; more interesting articles on how quantum mechanics and nano-tubes can be used in solar cells. One guy even suggested&nbsp; multiple existence of electrons as seen in double slit experimen can also be used to improve efficiency in solar cells. Solar cell's current limitation is very disappointing, I'm happy to see searchers are moving ahead in good pace.</font> <div class="Discussion_UserSignature"> <font size="2" color="#ff0000"><strong>Earth is Boring</strong></font> </div>

 

[Founding_Father]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I saw an article about a proposed method for concentrating solar energy for solar cells, andit used what looked like a wedge shaped piece of plastic with a coating that allowed light in but would not let it out.Is there any physical phenomina that would allow this to happen, or is this a scam?http://cleantechnica.com/2008/09/04/new-concentrated-solar-tech-simple-cheap-and-efficient/ <br />Posted by oklahoman</DIV></p><p>&nbsp;</p><p>It amazes me that with necessity comes innovation.&nbsp; Isn't this how it has always been?&nbsp; I have a question about how much energy the photon has, and why preventing it from escaping matters much.</p><p>&nbsp;</p><p><br /><br />&nbsp;</p>

 

[oklahoman]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Thanks for the link. The link led me to Live Science and&nbsp; more interesting articles on how quantum mechanics and nano-tubes can be used in solar cells. One guy even suggested&nbsp; multiple existence of electrons as seen in double slit experimen can also be used to improve efficiency in solar cells. Solar cell's current limitation is very disappointing, I'm happy to see searchers are moving ahead in good pace. <br /> Posted by emperor_of_localgroup</DIV></p><p>I see a lot of articles about some new ideas, and I mostly understand them.</p><p>Sadly the company website and the articles i have found for this particular idea say nothing at all about how the glass is supposed to let light in but not out. </p> <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I see a lot of articles about some new ideas, and I mostly understand them.Sadly the company website and the articles i have found for this particular idea say nothing at all about how the glass is supposed to let light in but not out. <br /> Posted by oklahoman</DIV></p><p>I used to work for a sign company that made illuminated glass signs.</p><p><br /> <img src="http://sitelife.space.com/ver1.0/Content/images/store/0/12/00627cde-0885-40a8-bc9b-cdfa57726959.Medium.jpg" alt="" /><br />&nbsp;</p><p>When light enters the glass at the edge, it stays inside the glass until it hits another edge. If you etch something in the glass, the light illuminates only the edges of the glass and whatever you etched. If you don't etch anything, the edges of the glass are very bright indeed. It seems like these guys might be working on this principle and concentrating the light onto solar cells along the edge.&nbsp;</p> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[why06]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I used to work for a sign company that made illuminated glass signs. &nbsp;When light enters the glass at the edge, it stays inside the glass until it hits another edge. If you etch something in the glass, the light illuminates only the edges of the glass and whatever you etched. If you don't etch anything, the edges of the glass are very bright indeed. It seems like these guys might be working on this principle and concentrating the light onto solar cells along the edge.&nbsp; <br /> Posted by SpeedFreek</DIV></p><p>Did the glass your company made use nanotubes? How did it work? </p> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[a_lost_packet_]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Did the glass your company made use nanotubes? How did it work? <br /> Posted by why06</DIV></p><p>I imagine the photons were quite content to bounce around off the smooth surface of the glass yet when they hit the etched portion, they scattered. </p> <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I saw an article about a proposed method for concentrating solar energy for solar cells, andit used what looked like a wedge shaped piece of plastic with a coating that allowed light in but would not let it out.Is there any physical phenomina that would allow this to happen, or is this a scam?http://cleantechnica.com/2008/09/04/new-concentrated-solar-tech-simple-cheap-and-efficient/ <br />Posted by oklahoman</DIV></p><p>The answer is yes, sort of.&nbsp; You can arrange the geometry to focus quite a bit of light through a relatively small hole into a cavity.&nbsp; That cavity heats up a radiates through the hole as a black body.&nbsp; It is not quite the same thing as a one-way filter for photons, but it does concentrate solar energy.&nbsp; </p><p>Just such a scheme was proposed and patented for use in a solar thermal rocket.<br /></p> <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I imagine the photons were quite content to bounce around off the smooth surface of the glass yet when they hit the etched portion, they scattered. <br /> Posted by a_lost_packet_</DIV></p><p>Yup, and if you use black paint or tape to seal the edges, the light bounces around until it can escape. In that picture above, if you taped up the edges of the glass, the etched area would get brighter. </p> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[centsworth_II]

<font color="#333399"><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>...if you use black paint or tape to seal the edges, the light bounces around until it can escape.</font> <font color="#333399">In that picture above, if you taped up the edges of the glass, the etched area would get brighter. <br /> Posted by SpeedFreek</DIV><br /></font>Wouldn't black paint absorb the light, not affecting the brightness of the letters?&nbsp; I think you would have to coat the edges with something reflective to brighten the letters. <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Wouldn't black paint absorb the light, not affecting the brightness of the letters?&nbsp; I think you would have to coat the edges with something reflective to brighten the letters. <br /> Posted by centsworth_II</DIV></p><p>Yes, come to think of it, you might be right - when the edges were sealed it was black on the outside and shiny on the inside. </p> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[oklahoman]

<p>My undestanding is that the light at those edges is not really concentrated, there is not really any more energy there than anywhere else in the glass, but there is just the illusion that there is because more of the light comes to your eyes from there.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> </div>

 

[why06]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Yes, come to think of it, you might be right - when the edges were sealed it was black on the outside and shiny on the inside. <br /> Posted by SpeedFreek</DIV></p><p>Oh I see. And I suppose if you mirrored the edges it would be possible to funnel the light to a point or edge. Pretty neat. </p> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[centsworth_II]

<p><font color="#333399"><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>My undestanding is that the light at those edges is not really concentrated, there is not really any more energy there than anywhere else in the glass, but there is just the illusion that there is because more of the light comes to your eyes from there.&nbsp; <br /> Posted by oklahoman</DIV></font><br />That's true. The point is that if the light is kept from escaping the edges, it will only be able to escape through the ground glass lettering and the letters will be brighter. The light is not directly funneled to the letters, it's just that the overall light level within the glass goes up if it is not allowed to escape through the edges.&nbsp; With a higher light level in the glass, more will escape through the letters.<br /></p> <div class="Discussion_UserSignature"> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That's true. The point is that if the light is kept from escaping the edges, it will only be able to escape through the ground glass lettering and the letters will be brighter. The light is not directly funneled to the letters, it's just that the overall light level within the glass goes up if it is not allowed to escape through the edges.&nbsp; With a higher light level in the glass, more will escape through the letters. <br />Posted by centsworth_II</DIV></p><p>The phenenoma involved in the sign is total internal reflectioin, the same thing that makes diamonds sparkle.&nbsp; Light hitting a boundary at less than a critical angle is completely reflected back into the material.&nbsp; At the edges the angle of incidence permits light to escape, unless you mirror the edges or put tape on them or some such sort of thing.&nbsp; At the ground letters the geometry is locally rough and some of the light hits the rough local surface at something greater than the critical angle and escapes, so you see the letters as illuminated.</p><p>This is the same effect that is used in optical fibers to keep the light in the fiber pipe until it gets to the end of the fiber, even going around smooth curves.&nbsp; But it does not provide a very effective means of concentrating extermal light to obtain power.&nbsp; </p> <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

<p>So what about if the face of the glass that light entered through was a lot larger than the face it exits through - i.e. a wedge shape? And if the top surface was coated such that light could enter, but not get back out through the larger face?</p><p>Would there be any benefit in taking the light falling on, say, a 10cm x 10cm area and concentrating it onto a solar cell only 1cm x 1cm, rather than simply having solar cells spread across the whole 10cm x 10cm area?&nbsp;</p> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[why06]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>So what about if the face of the glass that light entered through was a lot larger than the face it exits through - i.e. a wedge shape? And if the top surface was coated such that light could enter, but not get back out through the larger face?Would there be any benefit in taking the light falling on, say, a 10cm x 10cm area and concentrating it onto a solar cell only 1cm x 1cm, rather than simply having solar cells spread across the whole 10cm x 10cm area?&nbsp; <br /> Posted by SpeedFreek</DIV></p><p>Well yeah. I suppose its like catching an ant on fire with a magnifying glass. Even though the photoelectric cells may only produce electricity for certain frequencys of light. If one was to collect the frequencies that do power the cell over say a 100ft area and focus them into a 10ft area the solar cell should produce the powere output of a solar array ten times its size </p> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[a_lost_packet_]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Well yeah. I suppose its like catching an ant on fire with a magnifying glass. Even though the photoelectric cells may only produce electricity for certain frequencys of light. If one was to collect the frequencies that do power the cell over say a 100ft area and focus them into a 10ft area the solar cell should produce the powere output of a solar array ten times its size Posted by why06</DIV></p><p>It would all depend upon the efficiency and capabilities of the cell, wouldn't it?&nbsp; After all, the total solar energy isn't being increased.&nbsp; It's only the density being increased, right?&nbsp; If the system was designed to support that, then it would surely benefit from it.&nbsp; If not, it would probably be better to use that extra area for more solar cells. </p> <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>It would all depend upon the efficiency and capabilities of the cell, wouldn't it?&nbsp; After all, the total solar energy isn't being increased.&nbsp; It's only the density being increased, right?&nbsp; If the system was designed to support that, then it would surely benefit from it.&nbsp; If not, it would probably be better to use that extra area for more solar cells. <br />Posted by a_lost_packet_</DIV></p><p>Yes, and add in the relative cost of the collection sytem vs a larger array of solar cells.&nbsp; Economics is part of the issue too.<br /></p> <div class="Discussion_UserSignature"> </div>