Optical testing of panoramic lenses

Abstract

Here, we report for the first time the optical testing of modern 1.3, 5, and 8 megapixel panoramic lenses available on the market for security and surveillance applications. Our first test focused on the measurement of the image mapping and more particularly on the inverse of the instantaneous field of view expressed in pixels/degree (IFOV−1). This kind of measurement provides a valuable comparison parameter for the user community. The second test was a measurement of a modulation transfer function (MTF) system. All tested lenses were coupled with the same camera in order to measure the MTF system using the edge response. While this measurement is not a measurement of the MTF of the lens, it provides a basis for comparison between the different lenses. Our measurement shows that the IFOV is more robust than the MTF to manufacturing and assembly errors. This provides robustness to the unwrapping image post-processing. The MTF measurements show that all the tested lenses have an on-axis MTF of 35% at Nyquist frequency over 2 (Ny/2) for a 2.2 μm pixel pitch.