Freeform imaging system with resolution that varies with the field angle in two dimensions.

Area of Science:

• Optical Engineering
• Biomedical Optics
• Image Science

Background:

• The human eye exhibits non-uniform resolution, with higher acuity at the center and decreasing resolution towards the periphery.
• Existing imaging systems often struggle to replicate this variable resolution characteristic, limiting their applicability in certain scenarios.

Purpose of the Study:

• To design and present a freeform imaging system that emulates the human eye's resolution distribution.
• To achieve high resolution in the center and lower resolution at the edges of the field of view.

Main Methods:

• Utilized field-dependent parameters to characterize the system's optical properties.
• Developed a direct design method for realizing the desired resolution distribution.
• Designed an off-axis reflective freeform imaging system using three freeform surfaces.

Main Results:

• The designed system achieved high center resolution and low edge resolution within a 30°×30° field of view (FOV).
• The maximum instantaneous field of view (IFOV) ratio of center-to-edge resolution was 0.47.
• Attained good image quality with simultaneous improvements in resolution and FOV for a fixed detector.

Conclusions:

• A novel freeform imaging system successfully replicates the human eye's resolution characteristics.
• The proposed direct design method enables the creation of systems with tailored, field-dependent optical properties.
• This approach offers enhanced imaging capabilities by optimizing resolution and field of view simultaneously.