Proceedings Article | 24 October 2000
KEYWORDS: Wavefronts, Ray tracing, Point spread functions, Optical design, Monochromatic aberrations, Sensors, Image quality, Glasses, Solids, Charge-coupled devices
Different wavefront description possibilities are today available to the optical designer, usually in the form of polynomial fitting (seidel, Zernike, monomials...). This kind of representations have the general drawback of being based merely in the geometrical shape of the wavefront considered, calculated as a distribution of optical path differences, without taking into account the energetic distribution present in the wavefront. As a consequence, optimization of optical systems is carried on based only on geometrical criterions, while applications tend to rely more on energetic properties of the wavefront (detection on CCD arrays or photodiodes, image formation, etc.). In this paper we are proposing a new type of wavefront descriptor which includes its energetic distribution. The description is based on classical ray tracing procedures, in such a way that in each surface normal to the axis of the optical system, information on the position (z,y) and the director cosines (w.v) of the ray are known, together with the energy flux assigned to each ray (F). This allows obtaining the energetic distribution in any plane in the optical system together with the classical wavefront description based in OPD calculations, allowing to obtain complementary wavefront information. This complementary wavefront description has been applied to some simple optical systems (a large diameter cemented achromatic doublet, and a Cookes' triplet) showing how even in these very simple case the differences in the energetic distribution and the geometrical shape at the exit pupil plane are relevant. Such a fact is demonstrated by least- squares fitting of the surfaces to a monomial representation, allowing the determination of the different primary aberration coefficients. Finally, differences in the geometrical PSF and the energetic distribution calculated are plotted, to show they may achieve maximum deviations of up to 11% of the PSF value for the doublet, and 25% for the triplet. In addition, the deviations may be seen not to be a mere scaling factor, but a distribution depending on the image plane position. The wavefront descriptor presented is aimed to provide energy-based lens optimizations, as part of a global project named ROSA (Real Optical System Analysis) under current development in the Center for the Development of Sensors, Instrumentation and Systems (CD6) in the Universitat Politecnica de Catalunya.
