In this paper we report on the technical developments of the head worn display (HWD) for DARPA’s SCENICC
program. The goal of the SCENICC program is to provide the warfighter with vision capabilities exceeding normal
human vision. This is being achieved with an advanced imaging system that is able to capture the surrounding scene
with superior visual acuity, contrast sensitivity, and wavelength sensitivity. With this increased visual information
density, intelligent image processing provides imagery to the wearer’s eyes via an advanced HWD.
The goal of this HWD is to provide digital visual information at the limits of human perception over a field of view near
the human peripheral vision limits. This represents a tremendous amount of information requiring novel concepts in
order to achieve such ambitious goals. One important concept is the use of imaging optics located directly on the eye,
moving with the eye as it changes its gaze angle. A second concept is the use of demagnification optics to convert a
large, low spatial resolution image into a smaller, high spatial resolution image. This is done in conjunction with image
processing that is constantly modifying the image presented based on real-time pupil tracking.
In addition to enabling a high performance optical system, integrating the imaging optical components into contact
lenses eliminates much of the bulky imaging optics from the HWD itself creating a high performance wearable display in
a standard protective eyewear form factor. The resulting quantum advance in HWD performance will enable HWDs to
expand well beyond their current limited roles.
A volume hologram recorded with a lens array is proposed as a transflective screen for Head Worn Display (HWD)
systems. Design, fabrication as well as proof of concept are reported. Light from a projection system, with similar
properties to one mounted on the side of an eyewear, is efficiently diffracted towards the eye with an angular spread
given by the numerical aperture of the lenses forming the lens array. Using a dual-focus contact lens, high-resolution
images can be added to the HWD user’s normal vision, as light from the surrounding environment is transmitted through
the screen with low aberrations. This screen offers the possibility for small footprint and large field of view HWD’s.
Access to digital information is critical to modern defense missions. Sophisticated sensor systems are capable of
acquiring and analyzing significant data, but ultimately this information must be presented to the user in a clear and
convenient manner. Head-Worn Displays (HWDs) offer one means of providing this digital information. Unfortunately,
conventional HWDs occupy significant volume and have serious performance limitations. To truly offer a seamless
man/machine interface, the display must be able to provide a wide array of information in a manner that enhances
situation awareness without interfering with normal vision. Providing information anywhere in the eye's field of view at
resolutions comparable to normal vision is critical to providing meaningful information and alerts. Furthermore, the
HWD must not be bulky, heavy, or consume significant power. Achieving these goals of the ideal wearable display has
eluded optical designers for decades. This paper discusses the novel approach being developed under DARPA's
SCENICC program to create a high resolution HWD based on using advanced contact lenses. This approach exploits the
radically different concept of enhancing the eye's normal focus accommodation function to enable direct viewing of high
resolution, wide field of view transparent image surfaces placed directly in front of the eye. Integrating optical
components into contact lenses eliminates all of the bulky imaging optics from the HWD itself creating a high
performance wearable display in a standard protective eyewear form factor. The resulting quantum advance in HWD
performance will enable HWD's to expand well beyond their current limited rolls.
A projector with a height of 7 mm has been developed. The projector uses a two dimensional MEMS, a red and blue
diode laser and a second harmonic green laser. This projector module is able to display images with a WVGA resolution
while consuming 1.5 W. Due to the collimated nature of laser beams, the display has a depth of focus that is virtually
unlimited. Future MEMS developments will lead to even thinner projection modules. Furthermore, this projection
technology enables additional display systems such as head-up displays for vehicles.
This paper describes the design, fabrication, and characterization of the first MEMS scanning mirror with performance
matching the polygon mirrors currently used for high-speed consumer laser printing. It has reflector dimensions of 8mm
X 0.75mm, and achieves 80<sup>o</sup> total optical scan angle at an oscillation frequency of 5kHz. This performance enables the
placement of approximately 14,000 individually resolvable dots per line at a rate of 10,000 lines per second, a record-setting
speed and resolution combination for a MEMS scanner. The scanning mirror is formed in a simple
microfabrication process by gold reflector deposition and patterning, and through-wafer deep reactive-ion etching. The
scanner is actuated by off-the-shelf piezo-ceramic stacks mounted to the silicon structure in a steel package. Device
characteristics predicted by a mathematical model are compared to measurements.
A novel MEMS actuation technique has been developed for scanned beam display and imaging applications that allows driving a two-axes scanning mirror to wide angles at high frequency. This actuation technique delivers sufficient torque to allow non-resonant operation as low as DC in the slow-scan axis while at the same time allowing one-atmosphere operation even at fast-scan axis frequencies great enough to support SXGA resolutions. Several display and imaging products have been developed employing this new MEMS actuation technique. Exceptionally good displays can be made by scanning laser beams much the same way a CRT scans electron beams. The display applications can be as diverse as an automotive head up display, where the laser beams are scanned onto the inside of the car’s windshield to be reflected into the driver’s eyes, and a head-worn display where the light beams are scanned directly over the viewer’s vision. For high performance displays the design challenges for a MEMS scanner are great. The scanner represents the system’s limiting aperture so it must be of sufficient size; it must remain flat to fractions of a wavelength so as to not distort the beam’s wave front; it must scan fast enough to handle the many millions of pixels written every second; and it must scan in two axes over significant angles in order to “paint” a wide angle, two-dimensional image. Using the new actuation method described, several MEMS scanner designs have been fabricated which meet the requirements of a variety of display and imaging applications.