| Tucker_9966 |
hello, at the moment I am building the MK IV enclosure from www.diylabs.org/ for my lcd projector. I am at the stage were I need to building the lcd tray. I bought a split fresnel lens that is 15.5"x15.5". I don't know how to put in the split fresnel. Should I have one tray with the bottom fresnel and then stack another tray with the top fresnel right on top. So basically, should the two trays be touching or should I have a few inches between them?
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| Guy Grotke |
The short focal length fresnel goes in the tray so the smooth side is facing the lamp. Then you can put the longer focal length fresnel right on top of the other one, with the smooth side facing the LCD. (It is important that the centers of both are aligned with the center of the light path between the lamp and the LCD.) Mount the tray about an inch below the LCD and the lower fresnel's focal length from the lamp.
Or you might want to try using the fresnels in the split formation: Then you use a second fresnel tray about an inch above the LCD. Put the longer length fresnel in that tray with the smooth side facing away from the LCD. |
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