Traditional high dynamic range (HDR) photography is performed by capturing multiple images of the same scene with different exposure times, which are then digitally combined to produce an image with great detail in both its light and dark areas. However, this method is not viable for moving subjects since the multiple exposures are not captured simultaneously. Recently an alternative method has been developed in which beamsplitters are utilized to simultaneously record the same image on three identical sensors at different illumination levels. This process enables single-shot HDR photography as well as continuous HDR video. This paper describes the design of a 2.5x zoom lens for use in this application. The design satisfies the challenging working distance and ray angle constraints imposed by the placement of two beamsplitters between the lens and the image plane. The particular importance of first-order layout when designing a retrofocus zoom lens is also discussed.
*email@example.com Design study for a 16x zoom lens system for visible surveillance camera Anthony Vella*, Heng Li, Yang Zhao, Isaac Trumper, Gustavo A. Gandara-Montano, Di Xu, Daniel K. Nikolov, Changchen Chen, Nicolas S. Brown, Andres Guevara-Torres, Hae Won Jung, Jacob Reimers, Julie Bentley The Institute of Optics, University of Rochester, Wilmot Building, 275 Hutchison Rd, Rochester, NY, USA 14627-0186 ABSTRACT High zoom ratio zoom lenses have extensive applications in broadcasting, cinema, and surveillance. Here, we present a design study on a 16x zoom lens with 4 groups (including two internal moving groups), designed for, but not limited to, a visible spectrum surveillance camera. Fifteen different solutions were discovered with nearly diffraction limited performance, using PNPX or PNNP design forms with the stop located in either the third or fourth group. Some interesting patterns and trends in the summarized results include the following: (a) in designs with such a large zoom ratio, the potential of locating the aperture stop in the front half of the system is limited, with ray height variations through zoom necessitating a very large lens diameter; (b) in many cases, the lens zoom motion has significant freedom to vary due to near zero total power in the middle two groups; and (c) we discuss the trade-offs between zoom configuration, stop location, packaging factors, and zoom group aberration sensitivity.
The capacity to measure nanoscale features rapidly and accurately is of central importance for the monitoring of manufacturing processes in the production of computer integrated circuits. Parameters of interest include, for example, trench depth, duty cycle, wall angle and oxide layer thickness. The measurement method proposed here uses focused beam scatterometry, in which the illumination consists of a focused field with a suitably tailored spatially-varying polarization distribution. In an analysis that is analogous to classical off-null measurements as well as weak measurements in quantum mechanics, we predict that four or more parameters can be measured and distinguished with an accuracy consistent with the needs laid out in the semiconductor roadmap.
It is known that far-field scattered light requires <i>a priori</i> sample information in order to reconstruct nm-scale information such as is required in semiconductor metrology. We describe an approach to scatterometry that uses unconventional polarization states in the pupil of a high NA objective lens. We call this focused beam scatterometry; we will discuss the sensitivity limits to this approach and how it relates to micro-ellipsometry as well as low-NA scatterometry.