The image on a focal plane sensor is formed by incident radiation passing directly through the optics; although in some camera systems the light is scattered, reducing the contrast of and/or obscuring the image. Veiling Glare is the phenomena where the light entering an optical system is dispersed and partially washes out the sensor. This phenomenon can arise from many sources ranging from dirt on the lens, imperfections in the lens and anti-reflection coating to poor stray light rejection in the camera body, and the corrections can range from simply cleaning the system, rejecting a poor-quality lens or redesigning the camera. Veiling Glare Index evaluations as described in the ISO 9358 standard are difficult measurements to make. Veiling Glare Index test set ups described in the standard require a large space and/or a large integrating sphere. This paper will discuss the development of and results from a novel approach to the design and construction of a Veiling Glare Index test measurement system. The test equipment requires only 12.5% of the volume to perform the test compared to the large spheres described in the standard. The new design has additional benefits of 360° orientation of the off-axis glancing light angles. The instrument has adjustable light levels and continuous monitoring of the black and white targets so the contrast level is known at the time the measurements are made. The paper will include images obtained with the system of both excellent and marginal units under test.

Date Published: 28 April 2017
PDF: 9 pages
Proc. SPIE 10209, Image Sensing Technologies: Materials, Devices, Systems, and Applications IV, 102090W (28 April 2017); doi: 10.1117/12.2262881

Published in SPIE Proceedings Vol. 10209:
Image Sensing Technologies: Materials, Devices, Systems, and Applications IV
Nibir K. Dhar; Achyut K. Dutta, Editor(s)