Date

2022-7

Author

Aslan, Serhat Hasan

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Infrared lens design has many aspects similar to visible lens design. Optical aberration types and calculations, tolerancing procedures are applied in the same way in infrared lens design as in the visible lens design. However, there are many design aspects in infrared lens which are very different from visible lens design. One of these aspects is the narcissus effect in infrared lenses utilizing cooled infrared detectors. Narcissus effect is a very well known phenomenon in infrared lens with cooled detectors designed for high performance military electro-optical systems. It is the retroreflection of the cooled detector onto itself from refractive lens surfaces and seen as a dark spot at the center of the infrared image. It highly degrades the quality of the infrared image if it is not controlled in infrared lens design stages. Narcissus is controlled by two very important paraxial parameters in infrared lens design. While one of these paraxial parameters control the amplitude of the narcissus distribution, the other controls the variation of the narcissus distribution across the detector. Narcissus performance of an infrared lens is generally analysed at the far end of the optical lens design at which the main architecture of the optical layout, lens numbers and materials are already determined. If the narcissus performance of the designed lens is not satisfactory, very time consuming and inefficient iterations are needed in order to achieve a satisfactory optical performance from both optical aberrations and narcissus perspective. In this thesis, a narcissus control technique which enables optical designers to control narcissus effect in the early stages of the infrared lens design is constructed. Conventional paraxial narcissus control parameters are transformed into two narcissus control metrics which are used as a new type of aberration similar to the Seidel aberration coefficients. Narcissus performance of a lens can be taken into consideration in the early design stages beside optical aberrations with the help of the proposed thin lens narcissus model.

Subject Keywords

Infrared lens design, optical aberrations, narcissus effect, cooled infrared detectors

URI

https://hdl.handle.net/11511/98142

Collections

Graduate School of Natural and Applied Sciences, Thesis