Mark C. Sanson

MWIR continuous zoom with large zoom range

Multiple fields of view are achieved by two methods. The system can have optical groups that flip in and out to change the field of view, and/or optical groups that move axially to change the field of view. For flip in systems, the fields of view are discreet and they may have greatly different fields of view. A zoom system can have a continuous change in the field of view, but is often limited in the field of view range that can be achieved. Corning Incorporated has developed a thermal imaging zoom system with greater than 30X zoom range. With a solid fundamental design and appropriate selection of moving group focal lengths, the zoom system provides continuous changes in the field of view from the narrow field of view to the wide field of view. Corning accomplished this result in a short package with just two moving groups. The system is for the MWIR band.

Localized slope errors and their impact on image performance requirements

The performance effect of localized slope errors in an optical system will vary based on the system location as well as their magnitude. This paper looks at a method to model and analyze such errors.

Understanding product cost vs. performance through an in-depth system Monte Carlo analysis

The manner in which an optical system is toleranced and compensated greatly affects the cost to build it. By having a detailed understanding of different tolerance and compensation methods, the end user can decide on the balance of cost and performance. A detailed phased approach Monte Carlo analysis can be used to demonstrate the tradeoffs between cost and performance. In complex high performance optical systems, performance is fine-tuned by making adjustments to the optical systems after they are initially built. This process enables the overall best system performance, without the need for fabricating components to stringent tolerance levels that often can be outside of a fabricator’s manufacturing capabilities. A good performance simulation of as built performance can interrogate different steps of the fabrication and build process. Such a simulation may aid the evaluation of whether the measured parameters are within the acceptable range of system performance at that stage of the build process. Finding errors before an optical system progresses further into the build process saves both time and money. Having the appropriate tolerances and compensation strategy tied to a specific performance level will optimize the overall product cost.

Scanning Pupil Tolerancing

The tolerancing of lens systems has become more complex as system performance requirements tighten. The tolerancing of just the center thicknesses, surface radii, and surface irregularity are no longer sufficient for optical elements. This paper focuses on a new method to tolerance optical surfaces. There have been many papers written about different methods to tolerance optical surfaces which look to limit the artifacts left by different fabrication processes. The method proposed in this paper focuses on tolerancing to meet system performance, not the fight against the surface fingerprint of a particular fabrication process.

Development of MWIR continuous zoom with large zoom range

A thermal imaging zoom system has been developed for the mid wave infrared band with greater than 30X zoom range. The zoom system provides continuous changes in the field of view from the narrow field of view to the wide field of view. Athermalization was also a key feature included in the design. An active thermal compensation approach is being used to cover a broad thermal range. A preloaded rail approach is used to maintain boresight and vibration requirements. The final optical layout and mechanical design resulted in a system suitable for tactical and other harsh environments. The current design is very compact for the extremely large zoom range but, the lens layout also provides adequate space for folding. In this way the zoom system can be easily configured for applications with compact space claims such as small turrets or gimbals. The fundamental optical design has also been found to be capable of accommodating different camera formats (focal plane array size and F number).

Use of advanced sensitivity approach to novel optical compensation methods

Understanding the sensitivity of optical systems thoroughly can lead to improved tolerancing and compensation. An examination into a complex sensitivity analysis is shown. This analysis is used to improve the overall tolerancing and compensation of an optical system. We have developed a tool to facilitate this method of sensitivity analysis. An example of a novel compensation method is presented.