Speckle reduction and maintaining contrast in a LASER pico-projector using a vibrating symmetric diffuser

Area of Science:

• Optics and Photonics
• Display Technology

Background:

• Speckle noise is a significant issue in laser-based projection systems, degrading image quality.
• Achieving high contrast ratios and maintaining system efficiency alongside speckle reduction presents a technical challenge.

Purpose of the Study:

• To propose and evaluate a novel design for a laser pico-projector with reduced speckle contrast.
• To maintain high contrast ratios and system efficiency in the proposed pico-projector design.

Main Methods:

• Utilized a combination of two diffusers and a Voice Coil Motor (VCM) oscillator for speckle contrast reduction.
• Investigated two categories of diffusers: circular symmetric and elliptically scattering.

Main Results:

• Category 1 (circular symmetric diffuser): Speckle contrast reduced to 2.80%, contrast ratio 1200:1-1300:1, with a 1.50% decrease in system efficiency.
• Category 2 (elliptically scattering diffuser): Speckle contrast reduced to 6.50%, contrast ratio 1300:1-1400:1, with only a 1.00% decrease in system efficiency.

Conclusions:

• The proposed design effectively reduces speckle contrast in laser pico-projectors.
• The choice of diffuser impacts the trade-off between speckle reduction, contrast ratio, and system efficiency, with Category 2 offering a better balance.