A micro lense improves the performance of a camera and solar cells. This is achieved as light is concentrated into the most sensitive areas of a device. They are extensively used in the latest smartphone cameras in order to enhance the sensitivity and imaging speed when the light is low. Micro lens arrays are the key components in the coming generation of 3D imaging system as it presents certain useful optical properties like large field of view angles, low aberration & distortion, elevated temporal resolution and infinite depth of field. The latest advancements in digital photography, micro-lens fabrication technology, and computer hardware have led to the emergence of a multitude of commercially available, ready-to-use cameras.

The ultimate micro-lens array is obtained by replication technologies, including injection molding, hot embossing, and UV (ultra violet) molding.

  • Injection molding: a manufacturing process in which parts are manufactured by injecting molten material into a mold.
  • Hot embossing: a fabrication technique in which heat and force to press a master mold into polymers and plastics.
  • UV molding: a cost-effective technique of producing micro-optics on water scale. In this technique, a liquid polymer resin is UV (ultra violet)-cured between a substrate such as a glass and a transparent molding tool within a contact mask aligner.

Parameters

In order to describe the distinctive nature of microlenses, it is essential to measure certain parameters, including the focal length and quality of the transmitted wavefront. Out of the order techniques have been developed and new definitions have been proclaimed. For instance, locating the principal planes of such small lenses is practically not possible. Thus, measurements are usually made w.r.t. the lens or substrate surface.

Applications of Microlense Arrays

  • Microlens arrays are used in optical appliances, including light collection on CCD arrays, optical microscope, light-field camera, 3D Imaging & Displays, and LiDAR sensors.

  • Single microlenses are used to integrate light with optical fibers whereas micro-lens arrays are oftentimes used to enhance the light collection efficiency of CCD Arrays. They accumulate and focus light to prevent it from falling onto the non-sensitive areas of the CCD.
  • A micro-lens array used in tandem with a CCD array can make the core of a Shack-Hartmann Wavefront Sensor. Shack-Hartmann Wavefront Sensors can be used to describe the performance of an optical system. They are also used in applications where in near-real time monitoring of the wavefront is employed to regulate an adaptive optic so as to eliminate the wavefront distortion prior to creating an image.