Optical design of athermalised dual field of view zoom lens in long wave infrared (8μm - 12μm) spectral band using benefits of paraxial optics

This paper presents a methodology for designing an athermalised dual field of view zoom lens in long wave infrared (8μm - 12μm) spectral band by using the benefits of paraxial optics. By using this design methodology the optical designer can develop many types of complex optical systems in a straightforward way. The key feature of this design methodology relies on utilization of paraxial optics for defining the initial positions of the optical elements. The optical design is based on moving a single lens for changing the optical system’s FOV thereby reducing the number of moving parts and simplifying the assembly procedure of the system. The optical design begins with optimization process using paraxial optics. Then the optical design using paraxial optics is used as a template for designing the final optical system by lens material selection for compensating the shift in system’s focus due to thermal effects and lens thickness tuning.