The testing of vehicle windscreens has been tightened-up in recent times with the introduction of BS, DIN and ECE standards. These standards specify optical testing methods for parameters such as angular deviation, refractive power and optical distortion. Compliance with them is essential for windscreen manufacturers.
All of the optical test methods utilise specialist glass slides to give projected images which are then analysed. The slides themselves are manufactured by Pyser-SGI on standard 50mm x 50mm glass.
Slides with inclined lines are used in both DIN 52305 and BS 857 standards for testing angular deviation. Horizontal lines are used to test for refractive power. The test for optical distortion in ECE Regulation 43 calls for a matrix of clear dots on an opaque background to simulate oncoming headlights.
Please note that the standards products are all made to suit the traditional F90 focal length projectors. More recently these have become difficult to obtain so we also make slides for F100 focal length (please state focal length on your order).