When using a high-resolution Fourier transform spectrometer (FTS) in a cube-corner configuration, subharmonic ghosts are observed in the spectrum. These ghosts are attributable to parasitic diffuse reflections on the mirrors of the FTS arm. The reflected beams skip a part of the interferometer and travel a different path from the main beam thus experiencing a smaller optomechanical gain. These reflections are present in the reference laser channel as well as on the measurement channel, and each affect the estimated spectrum differently. The sampling grid generated by the reference laser has periodic errors that are synchronized with the fringe signal. The measured spectrum can therefore exhibit sampling jitter ghosts at submultiples of the reference laser wavenumber in addition to its own additive subharmonics. The diffuse reflection experiencing the nominal optomechanical gain, such as in a plane-mirror configuration, will impact directly on the instrument line shape and on the radiometric accuracy of the spectrometer since some radiation is not propagating at the expected angles in the instrument.
A novel laser trimming technique, fully compatible with conventional CMOS processes, is described for analogue and mixed microelectronics applications. In this method, a laser beam is used to create a resistive device by melting a silicon area, thereby forming an electrical link between two adjacent p-n junction diodes. These laser diffusible resistances can be made in less than a second with an automated system and their values can be in the range of 100Ω to a few MΩ, with an accuracy of 50ppm, by using an iterative process. In addition, these resistances can also be made to possess a thermal coefficient close to zero. We present the method used to create these resistances, the main device characterization and some insight on the process modeling.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.