I've been reading about screen circles here on the forum. Would over 4.7 per mm help correct that? The largest LCD you could use this with is a 14".
Fresnel Lens Type: Positive
Lens Application Infrared; Visible
Lens Geometry
Effective Focal Length (mm/in) 318 / 12.5
Grooves Per Millimeter (grooves per mm) 4.70
Lens Shape Square
Square Side Length (mm/in) 280 / 11
Thickness (mm) 2.30
Acrylic plastic lens, 1.491 index, 92% transmission
John
Fresnel Lens Type: Positive
Lens Application Infrared; Visible
Lens Geometry
Effective Focal Length (mm/in) 318 / 12.5
Grooves Per Millimeter (grooves per mm) 4.70
Lens Shape Square
Square Side Length (mm/in) 280 / 11
Thickness (mm) 2.30
Acrylic plastic lens, 1.491 index, 92% transmission
John