Principle and Applications of Microlens Arrays

I. Fundamental Principles

Microlens arrays (MLAs) are optical components comprising numerous miniature lenses arranged in specific patterns (e.g., hexagonal close packing or rectangular grid) on substrates. Their core functionality relies on individual lenslet's light manipulation:

Beam Splitting Principle:

Each microlens acts as an independent optical channel, dividing incident beam into sub-beams that form corresponding spot arrays at the focal plane. Key parameters include:

Focal length (f)

Aperture diameter (D)

Fill factor (>90% for high performance)

Wavefront Modulation:

Precise control of lenslet profiles (spherical/aspheric) enables phase modulation, which is fundamental for Shack-Hartmann wavefront sensors.

Light Field Sampling:

In plenoptic imaging, MLAs spatially sample angular light information to enable digital refocusing and 3D reconstruction.

II. Key Specifications

Pitch size: 10μm-1mm typical

Surface accuracy: <λ/4@632.8nm

Focal length uniformity: <±2% variation

Transmission: >95% with AR coatings

III. Major Applications

Advanced Imaging

Light field cameras (e.g., Lytro)

Confocal microscopy (sub-μm resolution)

Computational imaging techniques

Optoelectronic Displays

Laser projection (speckle reduction)

AR/VR near-eye displays (eyebox expansion)

Integral imaging (true 3D displays)

Laser Engineering

Beam homogenization (diode laser coupling)

Multi-focus parallel processing

Free-space optical communications

Emerging Fields

Quantum optics (single-photon detection)

Biochips (high-throughput screening)

ToF sensor optimization

IV. Fabrication Methods

Photoresist reflow process

Gray-scale lithography

Nanoimprint lithography

Laser direct writing

V. Development Trends

Freeform array configurations

Multi-level hybrid structures

Tunable MLAs (MEMS/liquid crystal)

Metalens-based MLAs (subwavelength features)