Some people are seeing the texture of an AN glass in copies of their film. So I did a real life test by taking a photo from a strip of 120 film, with and without AN glass, and comparing them.
Photo 1 - With AN glass
Photo 2 - Without AN glass
Camera: Pentax K5_II
Lens: Pentax-A 50mm f/2.8 Macro @ f/8.
Distance ring: Pentax Auto Nr.3, 25mm
Remote: Cable + Mirror up in advance
Light panel: Kaiser Slimline LED
AN glass: For Kaiser System V, 100x72.5 mm, 2mm thick, nr 4434.
Copied film: 120, HP5 plus
Photo 1 - With AN glass
The AN glass is taped to the light panel with the textured surface up, and the film strip is taped to the glass with the emulsion side facing the lens.
Photo 2 - Without AN glass
The photo without AN glass actually has the AN glass plate (2 mm thick) reversed with the textured surface facing the light panel, to get the same distance between film and the surface of the light panel as in photo 1. The film strip is taped to the glass with the emulsion side facing the lens.
The photo's are shown at 100% zoom, a screen dump was made, which was copied to a new image 400x400 pixels. Hence what you see is a crop from the 100% images.
The width of the photographed area is 24mm (0.945"), and the sensor of the APS-C camera is 4928x3264 pixels,
which gives a calculated scan resolution of about 4928/0.945 = 5200 dpi.
The sample from the film is an overexposed area, but it still has some density (hence the grain). An additional photo was taken with the film at 35mm distance from the light panel on a sheet of perspex, to be sure the grain was not an artefact from the surface of the light panel or the reversed AN glass. The result is identical to the photos above (photo 3).
Photo 3 - At 35mm distance from the light panel on perspex
Care was taken the film was perfectly flat against the AN glass, taped all around.
A cross was drawn on the emulsion side of the film with a black marker pen as a focusing aid (the black area in the photos). The viewfinder was extended with an angle finder at 2x for better focusing (manual).
Conclusion: The texture of an AN glass placed behind a film at the backside is not visible in a copy.