Zhenbo REN

zhenbren_{at}_eee.hku.hk

Digital Holography

1. Extended Focused Imaging and Depth Map Reconstruction

In this work, based on pixel-wise entropy minimization, an extended focused image and a depth map of the recorded 3D object are reconstructed. Comparison result with multiple focus metrics is also presented.

2. Autofocusing

In this work, autofocusing is achieved with focus metric of entropy minimization. It works successfully for intensity-only objects with multiple sections.

Autostereoscopic Display

In this project, we design and fabricate a prototype of autostereoscopic display system under LED illumination using a cylindrical diffractive optical elements sheet as the optical steering element. 8times 8 square plates are precisely stitched into a glass substrate with the size of 576 mm times 576 mm to obtain the sheet. The prototype has a 1.33 m^2 display panel, 384 times 144 resolution and a horizontal field of view of 60^{circ}.

My main work includes:

  1. Design and calculate the holographic optical element used for autostereoscopic display;

  2. Plot two sets of masks used for subsequent lithography and etching;

  3. Help with the fabrication of the optical element on 4 inch quartz substrates, with stepper exposure, inductive coupled plasma combined with ion beam etching, and measure the 4-level element with stylus profiler (KLA-Tencor P6);

  4. Help with the test of the prototype.

 

Step height measurement with stylus profiler.

Computer-Generated Holography

In this work, I mainly achieved two things:

  1. Use point-cloud algorithm and ray-tracing to compute the hologram of a 3D object.

  2. Use GPU to accelerate the computation speed of the generation of a hologram.

 

Animation of 3D rotating ring model.

 

Optical reconstruction of a rotating ring.