Emerson 609 projection TV

[old_tv_nut]

Originally Posted by Titan1a

Fresnel lens. Used to magnify the picture.

Yes, a Fresnel lens. But since magnification/projection is done by the mirror optics, part of this Fresnel's purpose is to direct the light out to the viewers (preventing the effect of looking down a tunnel where only one viewing position is good, or only part of the picture can be seen from any position). It controls the spread of the light such that multiple viewers can see it, yet it is not spread over a whole hemisphere to extreme angles where no viewers would be located.

I don't know how many layers the screen has and how much general diffusion is there in addition to the Fresnel. It would be interesting to check. Can you try looking at the picture from extreme right and left and extreme high and low, and see how far the viewing angle goes?

[Phil Nelson]

Originally Posted by old_tv_nut

I don't know how many layers the screen has and how much general diffusion is there in addition to the Fresnel. It would be interesting to check. Can you try looking at the picture from extreme right and left and extreme high and low, and see how far the viewing angle goes?

The screen appears to be a single layer, with a pattern of light horizontal lines (like extremely fine sandpaper scratches) on its rear surface and the pattern of concentric grooves on the front.

I looked at the screen from various angles, and tried to take some photos, and even a video, but the pics don't show anything very quantifiable, beyond "Yup, looks brighter head-on."

The brightness and contrast are clearly the best when you are looking head-on. The image looks quite good if you remain within an angle of about 45 degrees from the left or the right (or up or down). Beyond that, the picture is still coherent, but shown in shades of gray rather than vivid white & black.

Regards,

Phil