badgers
10/07/1999, 10:26 AM
I would like to share some information with all of those who are making you own lighting systems. The following is valid regardless of the light source(MH,Compact,NO fluorescents, HO, VHO, ect).
The reflector and LENS system has a huge impact on the light on your corals.
Have you ever seen what are called deep cell parabolic lenses on fluorescent troffers? They are a specular lens in a cube pattern.
The purpose of these lenses is to provide a cutoff angle to the light. These lenses direct the light down on the surface below.
Turn the lights off in the room and then look at your tank(tank lights on). How far out from your tank does the light go? All of this light is “wasted� in that it is not helping your corals. This light exits your light fixture and goes straight for the floor. Maybe it helps some photoplankton in the water column.
With MH lights you may have to consider heat when designing with parabolic lenses(some are plastic, some are aluminum) but a 3� deep lens has a cut off angle of 25 degrees. That means that light is concentrated in a 25 degree solid angle. (these square reflectors produce a pyramid shape not a cone)
Centering the lens in the middle of the tank can keep more light in your tank, and on your corals.
Most people seem to hang the lights about 3� above the tank for heat dissipation. Adding this lens can “focus� the produced light onto your target. You can get lenses 4� deep. The deeper the higher the transmission efficiency(theoretically)
Image exert from http://scientific-lighting.com/l30.html
http://scientific-lighting.com/planl30.gif
notice the wedge shape of the reflector. Light bounces off at the angle of incidence. This is how it shapes the light. Just having straight sides or hanging a fixture above the tank with nothing but air between the fixture and the top of the tank will “loose� this light. Its not lost you found it on your floor http://216.79.36.30/ubb/smile.gif.
Also consider the reflector behind the lamp and how that directs your light. http://tucson.com/fsi/OptiCAD/demohelp/demo.html
has some info and a demo of software to design from scratch a lens/reflector combo.(PS it is hard work) http://216.79.36.30/ubb/biggrin.gif I bought the lens and did some bounce calcs for the reflector.(my way is NOT optimal)
True design views the lens/reflector as a system. But even the addition of a Parabolic lens with a sharp cutoff may help many people put more light on their corals
Just some food for thought. http://216.79.36.30/ubb/biggrin.gif
Thank you for your time and have a good day
------------------
what did the fish say when it hit a concrete wall?
DAM!
[This message has been edited by badgers (edited 10-07-1999).]
[This message has been edited by badgers (edited 10-07-1999).]
[This message has been edited by badgers (edited 10-07-1999).]
[This message has been edited by badgers (edited 10-07-1999).]
The reflector and LENS system has a huge impact on the light on your corals.
Have you ever seen what are called deep cell parabolic lenses on fluorescent troffers? They are a specular lens in a cube pattern.
The purpose of these lenses is to provide a cutoff angle to the light. These lenses direct the light down on the surface below.
Turn the lights off in the room and then look at your tank(tank lights on). How far out from your tank does the light go? All of this light is “wasted� in that it is not helping your corals. This light exits your light fixture and goes straight for the floor. Maybe it helps some photoplankton in the water column.
With MH lights you may have to consider heat when designing with parabolic lenses(some are plastic, some are aluminum) but a 3� deep lens has a cut off angle of 25 degrees. That means that light is concentrated in a 25 degree solid angle. (these square reflectors produce a pyramid shape not a cone)
Centering the lens in the middle of the tank can keep more light in your tank, and on your corals.
Most people seem to hang the lights about 3� above the tank for heat dissipation. Adding this lens can “focus� the produced light onto your target. You can get lenses 4� deep. The deeper the higher the transmission efficiency(theoretically)
Image exert from http://scientific-lighting.com/l30.html
http://scientific-lighting.com/planl30.gif
notice the wedge shape of the reflector. Light bounces off at the angle of incidence. This is how it shapes the light. Just having straight sides or hanging a fixture above the tank with nothing but air between the fixture and the top of the tank will “loose� this light. Its not lost you found it on your floor http://216.79.36.30/ubb/smile.gif.
Also consider the reflector behind the lamp and how that directs your light. http://tucson.com/fsi/OptiCAD/demohelp/demo.html
has some info and a demo of software to design from scratch a lens/reflector combo.(PS it is hard work) http://216.79.36.30/ubb/biggrin.gif I bought the lens and did some bounce calcs for the reflector.(my way is NOT optimal)
True design views the lens/reflector as a system. But even the addition of a Parabolic lens with a sharp cutoff may help many people put more light on their corals
Just some food for thought. http://216.79.36.30/ubb/biggrin.gif
Thank you for your time and have a good day
------------------
what did the fish say when it hit a concrete wall?
DAM!
[This message has been edited by badgers (edited 10-07-1999).]
[This message has been edited by badgers (edited 10-07-1999).]
[This message has been edited by badgers (edited 10-07-1999).]
[This message has been edited by badgers (edited 10-07-1999).]