CAMBRIDGE, MA—Electronic holography is highly experimental today, but Draper engineer Gregg Favalora says he’s got evidence that the radical new technology already shows promise for improving glasses-free 3D displays. Through work with fellow engineers, Favalora has demonstrated holographic projection from a surface-emitting optical modulator that can be designed into a tablet-like display of the future.
It’s a promising data point, but a lot of questions remain about electroholography. The technology is extremely expensive and bulky today, requiring teams of experts to design and operate. Mainstream use of truly holographic 3D displays is still likely years away, with several breakthroughs required to unlock the promise of this radically different way of displaying an image.
Favalora believes that the many applications of holographic displays will drive their development past these hurdles. 3D displays are important for more than whiz-bang images in Hollywood movies. They can enhance a person’s retention and situational understanding, and help groups of people of different backgrounds come to consensus and make decisions by providing a common reference.
“3D displays leverage your perceptual machinery for a wide range of applications,” Favalora said. “For instance, if you have to comprehend something spatially, you remember it better if it is presented to you holographically than if you are interpreting a flat map. This could be helpful for soldiers who have to understand a complex terrain, or a medical radiation physicist who needs to create a complex treatment plan for external-beam cancer therapy.”
Draper’s holographic modulator for 3D display is notable because it is surface-emitting, can be scaled in area and field of view and requires fewer electrical inputs than an edge-emitting variant. The demonstrated modulator is composed of a lithium niobate substrate, optical waveguides, interdigital electrodes and a subwavelength backside grating that enables the device to carry 8 mm-long hologram segments. Unlike edge-emitting modulators, surface-emitting modulators can be configured to look like a computer tablet.
The modulator is also novel because it was designed with manufacturability in mind. “As we continue to develop and improve a suite of enabling components and processes, we can report the first demonstration, to our knowledge, of a scalable, monolithic surface-emitting electronic holographic modulator—an element of a 3D display that is made using standard microfab techniques,” Favalora said.
Last year Draper announced an earlier version of the holographic modulator that emits multi-perspective light in a column from its edge. The modulators of the earlier configuration can be stacked side-by-side in an array, creating a true holographic display. One advantage of the current version is that it provides holographic imagery directly from its surface, enabling compact tablet-like or desktop display.
Favalora, who is Group Leader of Sensors and Imaging Systems at Draper, is serving as a chair for the 2020 Stereoscopic Displays and Applications Conference (SD&A). As part of IS&T's International Symposium on Electronic Imaging, the SD&A event, January 27-29, brings together inventors, engineers and scientists to share the latest on stereoscopic 3D imaging, from capture to 3D display, to processing and perception.
Draper’s capabilities used in the development of the 3D display include microsystems, microfabrication, image and data analytics and integrated optics.