Parabolic reflector shape

Aston

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Joined
Mar 29, 2023
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6
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united kingdom
Hi all, I'm hoping to make a spotlight that will send a beam of light into the sky on a small budget, for my reflector i was going to use a satellite dish covered in Mirror Vinyl Wrap, however the focal point of my dish seems too far away (527mm (aprox 20")), so that got me thinking, what is the ideal depth of a parabolic reflector for an anti aircraft search light or Hollywood type spot/ searchlight? Thank you
 

LEDphile

Enlightened
Joined
Mar 8, 2021
Messages
301
For an omnidirectional source (typical lamp), deeper reflectors capture and focus more of the output from the lamp and give you less spill in the beam (so are more efficient at making a beam). You can get away with a shallower reflector if you use a directional source (think Cassegrain reflector)
 

Aston

Newly Enlightened
Joined
Mar 29, 2023
Messages
6
Location
united kingdom
For an omnidirectional source (typical lamp), deeper reflectors capture and focus more of the output from the lamp and give you less spill in the beam (so are more efficient at making a beam). You can get away with a shallower reflector if you use a directional source (think Cassegrain reflector)
Yes, I think my dish is too big and too shallow so I've bought a parabolic shaped fire pit, I think this will suit my needs better, thank you
 
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