Microlens arrays

Objective

Reproducible fabrication of refractive microlenses with parameters derived from system design calculations.

 

Technology

• Mastering by direct-writing grayscale lithography or binary mask lithography and reflow
  
• Replication by UV polymer molding or
• Transfer to silicon, glass or fused silica by reactive ion etching
• AR-coating, dicing
• Integration of aperture- / filter structures
• Double-sided patterning (tandem arrays)

 

Geometry of the lens arrays

• Spherical, cylindrical or elliptical lenslets; sag up to 100 μm
• Layout and focal length varying across the array / wafer („Chirp”)
• Lens diameter: 5 μm – 3000 μm
• Resolution / lens gap: 1 μm
• High fill factor, lateral precision
• Homogeneity of focal lengths: ±1 % across wafer
• Generation of aspheres by reactive ion etching (RIE)
• 100% fill factor of arrays by RIE assisted mastering

 

Replication by UV molding

• As thin polymer layer on glass, Si, etc.
• High lateral and axial precision
• High chemical / thermal stability
• On top of processed wafers (CMOS, VCSEL)

 

Applications

• Laser / fiber collimation
• Beam forming elements, homogenizer
• Fill factor enhancement on detector arrays
• Field-of-view matching for displays
• Miniaturized imaging systems, sensors