A CRT based RPTV screen is made up of two screens. The inner screen is called the fresnel and the purpose is to focus the light into a narrow beam to enhance the brightness output of the display. This creates what is called the beam effect which is what you see when you look at the image and move up and down or left to right and see the brightness level change. Without this screen the light would be far more scattered with a significant reduction in light output making a dark room necessary for decent results.
The outside screen is called the lenticular. It is a grooved screen and is what makes an RPTV in medium brightness room work. The purpose is to reflect external light from the screen while allowing the light on the other side to pass through. It is also excels at reducing or removing glare. This also adds to the beamy character of these displays in the left to right viewing positions as the groove in the screen reduces light output at these angles.
How many grooves are in the lenticular screen is called screen pitch. If you count how many grooves there are in an inch and then take that number times the width of the screen you will have the bandwidth of the screen. As an example if a spec states .52mm screen pitch that means every .52m there is a groove. With this info and some conversion you can determine the bandwidth of the screen without even measuring it.
RPTV's in general are bandwidth limited to about 1200 lines for various reasons and this is one of them. The Mits 65" screen has a bandwidth of about 2000 lines using a .72mm screen pitch. If you displayed 1920 on such a screen you would get artifacts because the two frequencies would optically beat against each other causing moire. The old Toshiba true 1920X1080 LCoS RPTV (out of production and abandoned by Toshiba) has a screen pitch of .1mm on a 57" screen. Plenty of bandwidth for 1920 lines.
On most of the newer RPTV displays there is yet another screen on the outside covering the lenticular screen called the screen protector and in most cases is permanent and not optional. Unfortunately this screen creates all kinds of glare and defeats the benefit of the lenticular screen. Many ISF calibrators will remove the protector or restack the screen assembly to remove this artifact.
Richard Fisher