Patent
Tunable optical filter having beam splitter and movable film filter
Fukushima Nobuhiro,Hiroshi Onaka +1 more
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TLDR
In this paper, a beam splitting mechanism for splitting an incident signal light beam into a first beam undeviated, a second beam deflected to one side of the first beam, and a third beam intercepted by a second photodetector is used to detect the third beam.Abstract:
A tunable filter module which can automatically make the center wavelength in the passband coincident with the center wavelength of a signal light beam according to variations in wavelength of the signal light beam. The tunable filter module includes a beam splitting mechanism for splitting an incident signal light beam into a first beam undeviated, a second beam deflected to one side of the first beam; and a third beam deflected to another side of the first beam, and a multilayer film filter located so as to transmit the first, second, and third beams. A first photodetector is located so as to detect the second beam, and a second photodetector is located so as to detect the third beam. A comparator is connected to the first and second photodetectors to compare outputs from the first and second photodetectors and output a differential signal indicative of the difference between these outputs. A tilt angle of the multilayer film filter is changed according to the differential signal so that the center wavelength in the passband of the multilayer film filter comes into coincidence with the center wavelength of the signal light beam.read more
Citations
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Yeming Gu,Michael Allen Spencer,Donald A. Collins,Jeffrey Peter Treptau,Stephen J. Ames,Daniel B. Seevers,Rex A. Aleshire,Hong Tang +7 more
TL;DR: In this paper, a produce data collector with minimal spectral distortion is proposed, which includes a light pipe having entrance and exit ends through which a portion of light reflected from a produce item travels, and a spectrometer adjacent the exit end of the light pipe which splits the portion of the reflected light into a plurality of wavelengths and produces signals associated with the wavelengths for identifying the produce item.
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Spatially variable bandpass filter monitoring and feedback control of laser wavelength especially in wavelength division multiplexing communication systems
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References
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Patent
Adjustable filter for tuning multimode optical signals
TL;DR: In this paper, an apparatus and a method of filtering a MM Wavelength Division Multiplexed (WDM) signal operating in the 1548 to 1560 nm region is described.
Patent
Light sensor with an adjustable spectral characteristic
Masahito Inaba,Masami Sugiyama +1 more
Abstract: A light sensor comprises optical filters, an interference filter and a photoelectric converting element which receives and photoelectrically converts light which has passed through the optical filters and the interference filter. An incident angle of the incident light on the interference filter can be changed so as to realize a desirable spectral sensitivity in a combination of the optical filters, the interference filter and the photoelectric converting element. The incident angle can be changed by a mounting structure that can rotate about an optical axis.
Patent
Electro-optically tuned rejection filter
William J. Gunning,John M. Tracy +1 more
TL;DR: In this paper, an electro-optically tunable Fabry-Perot filter is used to remove electromagnetic energy at a wavelength λ from a beam of electromagnetic energy, with an electrooptic crystal having parallel incident and exit surfaces, a first transparent electrode on the incident surface, a second transparent electrodes on the exit surface, an incident reflecting layer, and an exit reflecting layer.
Patent
Optical path sensor including a filter
Hans Dr Dammann,Reiner Orlowski +1 more
TL;DR: In this article, a filter constructed in a simple manner with low-cost elements two phase gratings are arranged one after the other in the beam direction, only one of the gratings being movable perpendicularly to the beam directions and in that the zero-order diffraction beams are directed towards a detector.