VerLASE extends Colour Conversion Patent
VerLASE Technologies has announced that US Patent No. 9,354,366 has been issued, extending aspects of its Chromover colour conversion technology.
The technology is a new approach for efficiently converting colours from inexpensive, widely available blue/violet light sources such as LEDs or laser diodes to any colour in the visible spectrum, in particular to the greens and reds needed for the ideal projection of images, whether in Near Eye Displays (NEDs) for Virtual (VR) and Augmented Reality (AR) applications, or in larger projectors.
Not only can the colour of the output light be tailored, but also spectral characteristics and directionality. Devices can be designed as a laser, directional LED, or in-between, depending on the application, according to the company.
The technology is suited for integrating with microLED displays for the next generation of NEDs needed in AR applications. The light sources and microdisplay technologies used today have many drawbacks, whether in colour quality, resolution, brightness, efficiency, or longevity, or a combination of all these.
MicroLEDs, with individually addressable pixels, would be preferred for higher brightness and efficiency leading to longer battery life and very compact physical forms, but they are typically only monochrome (blue /violet) emitters. Phosphors or Quantum Dots have not been shown to work with microLEDs; moreover, many AR approaches use diffractive or holographic waveguide optics which are sensitive to the input angles and spectral width of the input source light.
NEDs and their associated systems and software promise exciting new ways for users to interact with computers, mobile devices and their environments. A key challenge, however, surrounds the light sources needed for realistic colour projection of images onto a person's field of view, whether superposed 2D or full colour 3D holographic images, or even directly projected onto a user's retina using so-called Virtual Retinal Displays (VRDs).
VerLASE's Chromover technology is a wafer scale, inorganic thin film structure consisting of a novel resonator cavity around semiconductor Quantum Wells (QWs) engineered to downconvert light to a desired colour.
Input light sources can be monochrome (blue /violet) MicroLED displays, low cost LEDs or available laser diodes, depending on application. The resonant structure dramatically increases light absorption for high efficiency, and can be designed to emit in a controlled cone angle as spontaneous LED light, or to lase in stimulated mode as an optically pumped VCSEL, or in-between with tailored spectral properties including control of coherence to mitigate speckle, a big problem in projecting images with lasers.
"We can generate multiple colours on a single downconverting chip, whether a pixelated colour converting frontplane for emerging microLED displays, or an optically pumped RGB VCSEL array for VRDs using cheap laser diodes," said Ajay Jain, VerLASE's chief technical officer and inventor of the technology, adding that "both schemes make ultra small form factors possible for HMDs of the near future."
The company says it has been working with players in the VR /AR space to better define market requirements, leading to solutions that will enable more stylish, unobtrusive realisations of HMDs and NEDs.
Spun out of Vermont based Versatilis LLC in 2013 with an investment by Wakley Limited, a Hong Kong based private investment group, VerLASE focuses on technology development for VCSELs, LEDs, and optoelectronic devices involving novel materials, structures and processes.
