| Popis: |
Dual field of view sensors form the basis of many current IR systems. Emerging scenarios, however, are beginning to call for a wide range of field coverage, and are stretching the capabilities of dual field systems beyond the point where a comfortable balance of fields is obtainable. Provision of a 3rd field of view opens up an extended range of operational possibilities, and in many scenarios offers a sufficient level of functional availability when weighted against the cost of additional on-board FLIRs. The design evolution of a lightweight and compact triple field optical system is described. The system features a novel, optimum geometry carousel, which enables provision of 3 fields with a single mechanism. The design is modular and flexible, offering ratios up to 20:1 between the widest and narrowest field. Hybrid optical element assist in achieving performance with minimum element count, and a variant of the design featuring special materials (GaAs/KRS5) offers extended temperature capability and athermalization for specific applications. Configuration constraints are defined, limitations of alternative approaches explored, and characteristics of the preferred design are presented. Opto-mechanical design features are described which take advantage of the novel FOV change concept to produce a stable, balanced system which can offer advantages compared with a zoom in the operational environment. The modular nature of the configuration, which permits field of view and scanner interfacing to be readily tailored to suit any specific application while retaining commonality of main structural components and mechanisms, is also illustrated. |
