Martin Popp, Beat De Coi, Markus Thalmann, Radoslav Gancarz, Pascal Ferrat, Martin Dürmüller, Florian Britt, Marco Annese, Markus Ledergerber, Gion-Pol Catregn
KEYWORDS: Quantum efficiency, Distance measurement, Sensors, Light emitting diodes, Photonics, System on a chip, Analog electronics, Signal detection, System integration, Reflectivity
We present for the first time a fully integrated system-on-chip (SoC) for pixel-based 3D range detection suited for
commercial applications. It is based on the time-of-flight (ToF) principle, i.e. measuring the phase difference of a
reflected pulse train. The product epc600 is fabricated using a dedicated process flow, called Espros Photonic CMOS.
This integration makes it possible to achieve a Quantum Efficiency (QE) of >80% in the full wavelength band from
520nm up to 900nm as well as very high timing precision in the sub-ns range which is needed for exact detection of the
phase delay. The SoC features 8x8 pixels and includes all necessary sub-components such as ToF pixel array, voltage
generation and regulation, non-volatile memory for configuration, LED driver for active illumination, digital SPI
interface for easy communication, column based 12bit ADC converters, PLL and digital data processing with temporary
data storage. The system can be operated at up to 100 frames per second.
The restricted field of view of traditional camera technology is increasingly limiting in many relevant applications such
as security, surveillance, automotive, robotics, autonomous navigation or domotics. Omnidirectional cameras with their
horizontal field of view of 360° would be ideal devices for these applications if they were small, cost-effective, robust
and lightweight. Conventional catadioptric system designs require mirror diameters and optical path lengths of several
centimeters, often leading to solutions that are too large and too heavy to be practical. We are presenting a novel optical
design for an ultra-miniature camera that is so small and lightweight that it can be used as a key navigation aid for an
autonomous flying micro-robot. The catadioptrical system consists of two components with a field-stop in-between: the
first subsystem consists of a reflecting mirror and two refracting lens surfaces, and the second subsystem contains the
imaging lens with two refractive surfaces. The field of view is 10°(upward) and 35°(downward). A field stop diameter of
1 mm and a back focal length of 2.3 mm have been achieved. For
low-cost mass fabrication, the lens designs are
optimised for production by injection moulding. Measurements of the first omnidirectional lens prototypes with a high-resolution
imager show a performance close to the simulated values concerning spot size and image formation. The total
weight of the optics is only 2 g including all mechanical mounts. The system's outer dimensions are 14.4 mm in height,
with a 11.4 mm × 11.4 mm foot print, including the image sensor and its casing.
CSEM presents a highly integrated ultra-miniature camera module with omni-directional view dedicated to autonomous
micro flying devices. Very tight design and integration requirements (related to size, weight, and power consumption)
for the optical, microelectronic and electronic components are fulfilled. The presented ultra-miniature camera platform is
based on two major components: a catadioptric lens system and a dedicated image sensor. The optical system consists of
a hyperbolic mirror and an imaging lens. The vertical field of view is +10° to -35°.The CMOS image sensor provides a
polar pixel field with 128 (horizontal) by 64 (vertical) pixels. Since the number of pixels for each circle is constant, the
unwrapped panoramic image achieves a constant resolution in polar direction for all image regions. The whole camera
module, delivering 40 frames per second, contains optical image preprocessing for effortless re-mapping of the acquired
image into undistorted cylindrical coordinates. The total weight of the complete camera is less than 5 g. The system's
outer dimensions are 14.4 mm in height, with a 11.4 mm x 11.4 mm foot print. Thanks to the innovative PROGLOGTM, a
dynamic range of over 140 dB is achieved.
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