Microlenses are very small lenses. ‘Small’ means that they are less than 1mm in diameter, and sometimes as small as 10µm. According to an entry in Wikipedia, microlenses “can give good optical quality but sometimes unwanted effects arise due to optical diffraction as small features”.
Microlenses are used in different sectors and for different purposes. We used Mergeflow to find out more, and here are some examples of what we found:
Microlenses for medical use
The goal of Presbia, a medical device company based in Ireland, is to correct presbyopia. Presbyopia is an age-related focus dysfunction that results in the gradual loss of near vision. Presbia’s custom lenses are implanted into a patient’s non-dominant eye, in the hopes of helping the patient see near objects more clearly. To place the microlens into a patient’s eye, a small pocket is created in the cornea using a femtosecond laser. Following the implantation, the pocket seals naturally and the lens sits at the center of the visual axis.
You can see how Presbia’s system works in this YouTube video.
Microlenses for food testing
Timothy Swager’s lab at MIT has devised tiny microlenses from complex liquid droplets. These microlenses are comparable in size to the width of a human hair. Each droplet consists of an emulsion, or combination of two liquids, one encapsulated in the other, so-called Janus emulsions. The researchers decided to explore using Janus droplets as sensors because of their unique optical properties. If you are curious to know how they turn the droplets into sensors, you can read a more detailed description.
Thanks to these droplets, they found a new approach to identifying foodborne pathogens like Escherichia coli and other harmful bacteria. Such pathogens cause around 73,000 illnesses and 60 deaths every year in the USA. The new MIT test consists of an interaction between liquid droplets and bacterial proteins, which can be detected either by the naked eye or by a smartphone. Unlike existing approaches using expensive machines that require a 2-3 days process, MIT’s new technology does not require specialized instruments or technical training. The idea is to adapt the new technology into arrays of small wells, each containing droplets customized to detect a different pathogen and linked to a different QR code. This innovative idea could enable people e.g. in factories to easily scan and test the food before shipping it.
Microlenses for virtual reality
Lytro is an American company that develops light-field cameras. Light-field photography (also known as plenoptic photography) captures information about the intensity of light in a scene, and also information about the direction that the light rays are traveling in space. Lytro’s light field sensor uses an array of microlenses placed in front of a conventional image sensor that then captures intensity, color, and directional information.
Beyond making microlens-based devices, Lytro’s goal is to enable artists, scientists, and innovators to pursue their goals with an unprecedented level of freedom and control. One of their recent projects is Lytro Immerge. Lytro Immerge blends live action and computer graphics, using light field data captured by Lytro cameras. This technology is the first professional solution for cinematic virtual reality, and it seems to provide true presence for live action VR through six degrees of freedom. If you want to get more into details, you can find more information here.