Microlens arrays

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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