Abstract: A dual-optical displacement sensor system includes a scanner including a first and second scanner head including optical displacement sensors providing a first and second beam having a first optical axis (OA) and a second OA. A computing device or programmed circuit is coupled to receive time versus position data from measurements involving alignment target(s) including at least one knife edge pair including a first and second knife edge oriented in a first plane of the alignment target that is essentially perpendicular to the OAs positioned between the scanner heads for interacting with the beams, and implement at least one equation to analyze the data for determining a degree of alignment of the first and second OA. Using the degree of alignment, an algorithm is for automatic alignment of the OAs or assist instructions for a user alignment of the OAs that provides guiding steps for the user for the alignment.

Abstract: A dual-optical displacement sensor system includes a scanner including a first and second scanner head including optical displacement sensors providing a first and second beam having a first optical axis (OA) and a second OA. A computing device or programmed circuit is coupled to receive time versus position data from measurements involving alignment target(s) including at least one knife edge pair including a first and second knife edge oriented in a first plane of the alignment target that is essentially perpendicular to the OAs positioned between the scanner heads for interacting with the beams, and implement at least one equation to analyze the data for determining a degree of alignment of the first and second OA. Using the degree of alignment, an algorithm is for automatic alignment of the OAs or assist instructions for a user alignment of the OAs that provides guiding steps for the user for the alignment.

Abstract: A method of implementing OFDMA systems with enhanced preamble properties is presented. The transmit power is boosted during a preamble transmission, by utilizing preambles with a low Peak-to-Average Power Ratio (PAPR) property, as opposed to higher PAPR during the data portion of the transmission. Further, sets of preambles satisfying good PAPR properties in OFDMA systems are presented. The preambles satisfy a low Peak-to-Average Power Ratio (PAPR) property for numerous subsets of the usable subcarrier set. A method for generating a hierarchical set of preambles for OFDMA communication systems is described. The method hinges on the good PAPR properties of Golay's complementary sequences, and on hierarchical construction methods of larger complementary sequences out of smaller ones.