Field curvature correction method for ultrashort throw ratio projection optics design using an odd polynomial mirror...

Area of Science:

• Optics
• Optical Engineering
• Imaging Systems

Background:

• Traditional projection lenses face limitations in achieving ultrashort throw ratios (TR) and wide fields of view (FOV) while maintaining image quality.
• Field curvature is a significant challenge in designing compact projection systems, particularly those with very short TRs.

Purpose of the Study:

• To present a novel field curvature correction method for designing ultrashort TR projection lenses.
• To demonstrate the feasibility of this method through the design of a specific projection lens system.
• To analyze and compare the optical performance of the proposed lens against existing technologies.

Main Methods:

• The design incorporates refractive optical elements and a freeform odd polynomial mirror surface.
• Initial mirror surface profiles are calculated using hyperbolic segments based on ray tracing and reflection laws.
• Least-squares fitting is employed to optimize the freeform mirror surface using high-order odd polynomials.

Main Results:

• An example ultrashort TR projection lens was designed for a 50-inch screen at a 510 mm distance, achieving a 0.46 TR.
• The designed lens exhibits a modulation transfer function over 60% at 0.5 cycles/mm, an f-number of 2.0, and a 126° full FOV.
• Distortion is less than 1%, and the lens offers advantages in TR, f-number, FOV, and distortion compared to traditional and conventional short TR lenses.

Conclusions:

• The proposed field curvature correction method enables the design of high-performance ultrashort TR projection lenses.
• The designed lens achieves superior optical specifications, including ultrashort TR, wide FOV, and low distortion.
• This approach offers significant advantages over existing projection lens technologies for imaging systems.