The European Space Agency's space-based Darwin mission aims to directly detect extrasolar Earth-like planets using nulling interferometry. However, in order to accomplish this using current optical technology, the interferometer input beams must be filtered to remove local wavefront errors. Although short lengths of single-mode fibre are ideal wavefront filters, Darwin's operating wavelength range of 4 - 20 μm presents real challenges for optical fibre technology. In addition to the fact that step-index fibres only offer acceptable coupling efficiency over about one octave of optical bandwidth, very few suitable materials are transparent within this wavelength range. Microstructured optical fibres offer two unique properties that hold great promise for this application; they can be made from a single-material and offer endlessly single-mode guidance. Here we explore the advantages of using a microstructured fibre as a broadband wavefront filter for 4 - 20 μm.
The European Space Agency (ESA)[1] foresees several robotic missions aimed for the preparation of the future Human Exploration of Mars. To accomplish the mission objectives Imaging LIDARs are one of the identified technologies that shall provide essential information to the spacecraft Guidance, Navigation and Control (GN&C) system. ESA awarded two technology development contracts to two industrial teams for the development and demonstration of novel technologies for Imaging LIDAR sensors. Both teams designed and are manufacturing an Imaging LIDAR breadboard targeting one specific application. The objective of using novel technologies is to reduce substantially the mass and power consumption of Imaging LIDAR sensors. The Imaging LIDAR sensors shall have a mass <10kg, power consumption <60Watt, measure distances up to 5000m, with a field of view (FOV) of 20x20 degrees, range resolutions down to 2 cm, and a frame rate higher than 1 Hz.
KEYWORDS: Space operations, LIDAR, Sensors, Spatial resolution, Single photon, 3D metrology, Super resolution, Stereoscopy, 3D image processing, Detector arrays
3D LIDAR imaging is a key enabling technology for automatic navigation of future spacecraft, including landing,
rendezvous and docking and rover navigation. Landing is typically the most demanding task because of the range of
operation, speed of movement, field of view (FOV) and the spatial resolution required. When these parameters are
combined with limited mass and power budget, required for interplanetary operations, the technological challenge
becomes significant and innovative solutions must be found. Single Photon Avalanche Photodiodes (SPADs) can reduce
the laser power by orders of magnitude, array detector format can speed up the data acquisition while some limited
scanning may extend the FOV without pressure on the mechanics. In the same time, SPADs have long dead times that
complicate their use for rangefinding. Optimization and balance between the instrument subsystems are required. We
discuss how the implementation of real-time control as an integral part of the LIDAR allows the use of SPAD array
detectors in conditions of high dynamics. The result is a projected performance of more than 1 million 3D pixels/s at a
distance of several kilometers within a small mass/power package. The work is related to ESA technology development
for future planetary landing missions.
We offer an approach to the analysis of measurements performed by the laser beam analyzers. The proposed criterion for accuracy of the laser power distribution measuring apparatus can be used for assessing the potential ability of laser beam analyzers for high accuracy evaluation of linear dimensions. The criterion takes into account the quality of the optics and scanning system, detector performance, and the method of measurement. The test setup allows testing of errors in the full power assessment and diameter measurement. These errors are connected to real physical values and therefore can be used to compare the performance of arbitrary laser beam analyzers. The key point is that the process of measurement is considered totally in the spatial frequency domain. This allows us to put the method specifics of the measurement in comparable terms, extract some important features of the measurement crosses, and create a base for comparing instrument accuracy.
The paper deals with dependence between the parameters of laser microprocessing system, used to scribe a microchannel on the floppy disk magnetic layer, and the parameters of the channel caused `missing pulse' information error, generated while reading the disk. The results are used to precise the laser microprocessing aimed at ensuring that both precise microchannel and information pulse.
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