for makiing a video projector?
I mean, if I want to build something compact, which parts can I use?
Regards
I mean, if I want to build something compact, which parts can I use?
Regards
Parts useable
WEll if changing light source then...................
OHP objective lens assmebly (VERY $ to make- so worth used)
First surface mirror in that assembly.
The boom and the focus arm.
The stage (fresnel sandwhich)
By useing the stage (dont split unless HAVE to) the lenses and mirror you have a very nice match of optics that cost the OHP co. some serious $ to both buy and figure out (R&D research and development) which is usually the most $ aspect of projectors. Design and layout. A ohp is actually pretty compact for what we are doing. To go smaller means smaller LCD which means harder to get light through-smaller image projected over throw distance-lower res. Unless your rich, then 3- high res stamp size monochrome panels with a prism and color filtering mirrors can be shoe box size and match any comercial unit. Bulb will be expensive too from being so small and bright. Only cheap bright bulbs are large-and the reason being material and manufacturing costs. THis will change in about 50 years LOL.
WEll if changing light source then...................
OHP objective lens assmebly (VERY $ to make- so worth used)
First surface mirror in that assembly.
The boom and the focus arm.
The stage (fresnel sandwhich)
By useing the stage (dont split unless HAVE to) the lenses and mirror you have a very nice match of optics that cost the OHP co. some serious $ to both buy and figure out (R&D research and development) which is usually the most $ aspect of projectors. Design and layout. A ohp is actually pretty compact for what we are doing. To go smaller means smaller LCD which means harder to get light through-smaller image projected over throw distance-lower res. Unless your rich, then 3- high res stamp size monochrome panels with a prism and color filtering mirrors can be shoe box size and match any comercial unit. Bulb will be expensive too from being so small and bright. Only cheap bright bulbs are large-and the reason being material and manufacturing costs. THis will change in about 50 years LOL.
Thanks, Altec
If you don't mind me asking (I have not researched this subject thoroughly), what does it mean, to split the fresnel lens?
Also, what causes the OHP to make a rainbow on the screen? Is this a defect to look out for?
Lastly, what makes the OHP lose light in the corners of the image?
Can these issues be overcome?
If you don't mind me asking (I have not researched this subject thoroughly), what does it mean, to split the fresnel lens?
Also, what causes the OHP to make a rainbow on the screen? Is this a defect to look out for?
Lastly, what makes the OHP lose light in the corners of the image?
Can these issues be overcome?
OHP problems
I can't say for sure but both the rainbow and losing the corners could be from the bulb being out of focus. There is an optimum distance that the bulb must be from the stage (fresnel) If it is too close you get the reduced corners with a rainbow effect arround the edges, if too far away you get reduced light output.
I'm sure this explaination is way too simplified but I have a projector that has a knob to focus the bulb and these are the results that I get when adjusting it. I also have a 3M 9550 and the bulb assembly can be adjusted by loosening a screw inside and moving the whole assembly.
Hope this helps.
I can't say for sure but both the rainbow and losing the corners could be from the bulb being out of focus. There is an optimum distance that the bulb must be from the stage (fresnel) If it is too close you get the reduced corners with a rainbow effect arround the edges, if too far away you get reduced light output.
I'm sure this explaination is way too simplified but I have a projector that has a knob to focus the bulb and these are the results that I get when adjusting it. I also have a 3M 9550 and the bulb assembly can be adjusted by loosening a screw inside and moving the whole assembly.
Hope this helps.
buckster is 100% correct. The KEY to any projection is to have the bulbs reflector AND the strage tuned to the hight of the objective lens. The F1's must match. THis is important. To tune start at bulb. Move the reflector till it beams the cone of light mainly into the ohp objectves. The Ref is actually the same as a magnifying glass. it bends light the same-just not passive. So it has a Focal length just like any lense does. THe rainbow will be gone when aligned. it comes from the bulb being offset from the lens and your picking up the light rays refracted to harshly to be used at edges of lense assembly. Double lense do this. Triplets dont. so badly. THen align you stage if need be. Nice bright image will result.
"what does it mean, to split the fresnel lens?"
I dont advise you do it if going with all ohp parts as it screw up the focal lengths. Some do it though. There are two that are glued back to back on a OHP-seperate them put on before LCD and on after. Like I said though easier to buy another small one and use stage as it was designed as it is needed to aim light just right into the lenses.
"Lastly, what makes the OHP lose light in the corners of the image"
Welp after tuning -it comes down to OHP's being very unadvanced. IE they havent changed in nigh on 30 years much other than bulb tech. The ref in them SUCK and dont grab hardly any light. Perfect would be to use a parabolic eliptical reflector where 1/8 radious is = to center of bulb for froward thrown light. Move bulb inward more and you get a laser beamish type cone-hehe.
"what does it mean, to split the fresnel lens?"
I dont advise you do it if going with all ohp parts as it screw up the focal lengths. Some do it though. There are two that are glued back to back on a OHP-seperate them put on before LCD and on after. Like I said though easier to buy another small one and use stage as it was designed as it is needed to aim light just right into the lenses.
"Lastly, what makes the OHP lose light in the corners of the image"
Welp after tuning -it comes down to OHP's being very unadvanced. IE they havent changed in nigh on 30 years much other than bulb tech. The ref in them SUCK and dont grab hardly any light. Perfect would be to use a parabolic eliptical reflector where 1/8 radious is = to center of bulb for froward thrown light. Move bulb inward more and you get a laser beamish type cone-hehe.
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