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htguy1
Joined: 30 Jul 2008
Posts: 99
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| Posted: Mon Sep 26, 2011 2:09 am Post subject: Any body ever try directly coupling Lense w/o a c-element? |
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HI,
Ok so I know this sounds like a silly idea, but it seems to me that the extra plastc and air gap in our LC machines leads to ore light scatter lower contrast ratings etc. I was thinking that if I siliconed the lense edge between lense and the black plastic outer shell and then found a rubber bellows to fit between lense and tube housing I could ditch the c -element.
Anyone ever try this? It just seems like it could lead to some nice benefits if I can find the right parts to try it.
Thanks
God bless...
Mark
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zGman
Joined: 22 May 2006
Posts: 599
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| Posted: Mon Sep 26, 2011 3:19 am Post subject: |
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Well - That is interesting - however you may want to consider the possibility that the c-element
is in fact an optical element, and the lens' parameters depend on its presence in the optical path.
ie. the refraction of light occurs at the interface of elements with different refractive index. The
index is pretty well matched between the tube glass and glycol and glycol to c-element, the big
change is the c-element to air and the curvature is precise. The c-element is actually the
first element in the lens.
G
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Axatax
Joined: 01 Nov 2006
Posts: 403
TV/Projector: Sony VPH-G70Q (aka Barco Cine8 Onyx)
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| Posted: Mon Sep 26, 2011 9:00 am Post subject: |
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Fail.
The C-element is the first optical element in the lens. You can't "remove" it without re-engineering the entire lens assembly.
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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htguy1
Joined: 30 Jul 2008
Posts: 99
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| Posted: Mon Sep 26, 2011 3:01 pm Post subject: |
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Hi,
Well, glad I asked before I tried it  Thanks guys.
God bless...
Mark
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Mon Sep 26, 2011 9:35 pm Post subject: |
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It's not just the c-element you have to consider. The liquid between the tube face and the c-element make up the first "lens" in the path. If you had a empty chamber (no coolant) it would not focus.
_________________
Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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zGman
Joined: 22 May 2006
Posts: 599
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| Posted: Mon Sep 26, 2011 11:55 pm Post subject: |
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Yes the glycol is needed for index matching but the glycol itself does not "bend" light - refraction
occurs at the interface of different refractive index materials -the index of the tube glass is
approx 1.5, the glycol is approx 1.4 and the acylic in the c-element is about 1.4, so there
is a pretty good match. The actual 'lens' is at at the interface of the c-element to air (index ~ 1.0 )
The diagram Tom posted is pretty good to see the ray tracing at work...
G
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Tue Sep 27, 2011 3:57 am Post subject: |
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| zGman wrote: | Yes the glycol is needed for index matching but the glycol itself does not "bend" light - refraction
occurs at the interface of different refractive index materials -the index of the tube glass is
approx 1.5, the glycol is approx 1.4 and the acylic in the c-element is about 1.4, so there
is a pretty good match. The actual 'lens' is at at the interface of the c-element to air (index ~ 1.0 )
The diagram Tom posted is pretty good to see the ray tracing at work...
G |
G, Your reading to much into this. The liquid IS the lens. The tube face dictates the shape of one side of the lens and the c-element dictates the other. The fact that the first element Is liquid allows for infinate mechanical focus adjustment. This is where AmPro failed. They tried to vary the relationship of the lens to the c-element. The rest of the crt community changed the relationship of the c-element to the tube face (the way it was intended). A liquid coupling is nothing more or less then a lens that you have the ability to change the shape of.
_________________
Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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zGman
Joined: 22 May 2006
Posts: 599
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| Posted: Tue Sep 27, 2011 3:02 pm Post subject: |
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OK - That is a good way of looking at it - thanks for explaining.
G
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