Depth of focus increase by multiplexing programmable diffractive lenses

Area of Science:

• Optics and Photonics
• Image Science
• Display Technology

Background:

• Traditional imaging systems often suffer from a limited depth of focus (DOF), restricting their ability to capture sharp images over a range of distances.
• Achieving an extended DOF typically requires complex optical setups or specialized lens designs.

Purpose of the Study:

• To propose and experimentally validate a novel method for significantly increasing the depth of focus (DOF) of an imaging system.
• To demonstrate the effectiveness of spatially multiplexed diffractive lenses on a liquid crystal display (LCD) for enhanced DOF imaging.

Main Methods:

• Spatially multiplexing multiple diffractive lenses onto a single programmable liquid crystal display (LCD) using a random scheme.
• Calculating the Modulation Transfer Function (MTF) to evaluate image quality and comparing it with single-lens and multiplexed-lens systems.
• Obtaining experimental Point Spread Functions (PSF) and imaging an extended object under spatially incoherent monochromatic light.

Main Results:

• The axial irradiance distributions from individual lenses were overlapped to create an extended focal depth.
• Experimental results showed a high increase in the depth of focus when using multiplexed lenses compared to a single lens.
• Image quality was assessed using MTF and PSF analyses, confirming the benefits of the proposed technique.

Conclusions:

• The proposed method of spatially multiplexing diffractive lenses on an LCD effectively extends the depth of focus of imaging systems.
• This technique offers a practical and efficient approach to enhance DOF without requiring complex optical hardware.
• The experimental validation confirms the significant improvement in DOF achievable with this programmable optical element approach.