Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
2000-08-19
2003-06-10
Pascal, Leslie (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200, C359S199200
Reexamination Certificate
active
06577417
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of optical data processing.
Homodyne and heterodyne detection is one of the most important concepts in information processing theory. Several other concepts are associated with it, such as phase-sensitive detection, lock-in detection, frequency and time-division demultiplexing and base-band demodulation, time-integrative correlation, and many other devices, which can be fined the literature; see A. B. Carlson),
communication systems: An introduction to signal and noise in electrical communication,
2
Edition
(MaGraw-Hill, New York 1975)
These concepts have been used extensively in designing many electronic devices. For example the lock-in amplifier is used routinely in many microscopic and tomographic systems, see “Kyuman Cho, David L. Mazzoni and Cristopher C. Davis” Measuring of the local slope of the surface by vibrating-sample heterodyne interferometery: new method in scanning microscopy, Kyuman Cho, David L. Mazzoni and Cristopher C. Davis)(for as a data acquisition tool, further they are often used in pulling the signal which is embedded in very high noise environment (reference in noise reduction within signals) (M. L. Mead, Lock in amplifier: Principles and applications, (Peregrinus, London 1983). Lock-in detection is also used in controlling machine vibrations, and components within servo systems for tracking CD, DVD and magneto-optics disk; references problems of tracking: Casimer Maurice DeCusatis, Lawrence Jacobowitz, “Active Tracking system for optical disk storage,” U.S. Pat. No. 5,793,718. See also Hubert Song et al. Non-contact servotrack writing with phase sensitive detection,” U.S. Pat. No. 5,991,112. Time integrative correlators are used in pattern recognition devices; e.g. applications involved in identifying a specific optical bit pattern for header recognition or code-division demultiplexing, or data base search in high speed optical communication systems or soft ware applications. See Jun Shan (Optical bit pattern recognition by use dynamic grating in erbium doped fiber) Optics letters, Volume 22, 1757-1759 (1997) Frequency and time-division, base band demodulators are also some of the most important components used for constructing telecommunications systems, networking, cable TVs. See A. B. Carlson, communication systems: An introduction to signal and noise in Electrical communication, 2 Edition (MaCraw-Hill, New York 1975).
In the recent years much attention has been devoted to the use of wavelength division demultiplexer as one of the main components for telecommunication systems base on fiber optics. See for example Optical Networking Volume 1 Januray 2000). See also the following U.S. patents: Optical Add-Drop multiplexer compatible with very dense WDM optical communication systems. U.S. Pat. No. 5,982,518 Nov. 9, 1999; Li “Wavelength and Bandwidth tuneable optical system,” U.S. Pat. No. 5,841,918. This patent discloses a tunable Bragg cell; see also Daniel J. Fritz, Timothy J. Bailey and Mass Gary, “All Fibre wavelength selective optical switch,” U.S. Pat. No. 5,446,809.
Wavelength division demultiplexing not only important for telecommunication but it has significant applications in other areas including biomedical applications, remote sensing, multispectra and hyperspectra pattern recognition and fiber sensors. Wavelength division demultiplexers can employ a Fabry-Perort interferometer, including MEMS structures, Bragg Grating either in fiber, volume holographic materials, or fabricated structure for layers of Electro-optic materials, and a Mach_Zender interferometer. See the following material in Optical Society of America: Handbook of Optics, volume I and II. For enhancing the capability of transferring the data in telecommunication systems, most recently it was proposed to combine either wavelength division multiplexing (WDM), with either time (TDM) or frequency multiplexing (FDM). In the receiving end it was proposed that the wavelength demulteplexing is done optically and time or the frequency division demultiplexing is done electronically.
I believe that up until now, no one optical device is present in the prior art which can do both of these operations simultaneously. I introduce a new device concept herein that can be utilized for combining both WDM and FDM or TDM demulteplexing on the same device. I name the new device HTWDM (heterodyne time wavelength division demultiplexing), because the new device not only combines WDM with FDM or TDM, but it can combine other homodyne detection functionality with wavelength division demulteplexing functionality. In more general terms my invention can combines K-vector demultiplixing with heterodyne detection (k vector division demultiplexing will be illustrated further through the text of this invention). This combined functionality has enormous significance for many applications.
I introduce herein a general concept for homodyne and heterodyne detection based on K-vector tunable optical cells. An important application is use of the optical cells as wavelength-division demultiplexers (or in more general terms K vector division demultiplexers and mixing for homodyne heterodyne detection or time division demultiplexing will be performed in accordance with the present preferred inventive emdodiments on a single optical component. This component can operate as a low pass filter if the modulation is very fast. This is in contrast with the distributed Bragg reflector laser structure of U.S. Pat. No. 5,020,153 of Choa et al. whose invention is limited to WDM (not K-vector demultiplixing) and heterodyne detection, without any consideration for time division demultiplixing. Further in the Choa patent, each of the operations of WDM and heterodyne detection were performed in separate components within the integrated device. The Chao grating was used for WDM, whereas the heterodyne signal detection was produced by mixing the signal being detected with an external beat signal. In contrast with Chao, who discloses using distributed bragg grating within his device, the K vector selector can take numerous forms as will be illustrated. Thus the present invention can have numerous application in variety of areas ranges from telecommunication, tracking in CD and DVD, fluorescent microscopy; see M. Schrader and S, W. well, S. W. Hell, H. T. M. Van der Voort, “Three-dimensional super-resolution with 4-PI-confocal microscopes using image restoration,” Journal of applied physics, 84, 4033-4041 (1998) or in Foliage averaging; see Part 1: Foliage Attention and Back scatters Analysis of SAR images, J. G. Fleischman, S. Ayasli, E. M. Adams, D. R. Gosselin. IEEE transaction on aerospace and electronic systems, Vol.32, No 1 January 1996 P 135-144; or for applications in Lidar (light wave radar); see J. G. Fleischman, S. Ayasli, E. M. Adams, D. R. Gosselin Part III: Multi channel Whitened of SAR imagery IEEE transaction on aerospace and electronic systems, Vol.32, No 1 January 1996 P 156-164). In this invention also I propose a gratings to be tunable over wide range, these grating can be integrated within the structure of distributed feed back laser or vertical cavity lasers for enhancing the range of tunabiliy. It can also serve as part of add/drop demultiplexer. Other uses of the present invention include microscopic and tomographic sytems, multispectra and hyperspectra pattern recognition, non-destructive testing instruments, atmospheric turbulence correction devices, remote sensing systems and velocity measuring devices.
The significance of the present invention in connection with various applications can be understood as follows: (1) In Telecommunication for increasing the channel capacity of LAN (Local area net work and WAN (wild area net work), TV Cables, Telemetry systems. (2) In all forms of homodyne and heterodyne microscopy and tomography imaging for enhancing sensitivity, which can be achieved by averaging the measurement at various wavelengths. (3) In nondestructive testing, for controlling the operation of several machines, in which each wa
Nathans Robert
Pascal Leslie
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