Naohisa Mukohzaka

Bio: Naohisa Mukohzaka is an academic researcher from Hamamatsu Photonics. The author has contributed to research in topics: Spatial light modulator & Liquid crystal. The author has an hindex of 14, co-authored 37 publications receiving 876 citations.

Diffraction efficiency analysis of a parallel-aligned nematic-liquid-crystal spatial light modulator.

Abstract: An optically addressed parallel-aligned nematic-liquid-crystal spatial light modulator is developed for applications in optical information processing and interferometry. Its performance, including diffraction efficiency, is measured, and a theoretical analysis of diffraction efficiency is performed. A comparison between the experimental results and the theoretical analysis shows good agreement. The diffraction efficiency of near-sinusoidal gratings written on the device is of the order of 30%, which is close to theoretical maximum.

High Efficiency Electrically-Addressable Phase-Only Spatial Light Modulator

Abstract: To realize a high efficiency electrically addressable phase-only modulator, we have coupled a liquid crystal display (LCD) to an optically addressed parallel-aligned nematic liquid crystal spatial light modulator (PAL-SLM) with a set of lenses. Phase modulation exceeding 3ϖ at 532 nm wavelength was obtained. We obtained linear transfer characteristics for phase modulation at various desired phase levels after calibration and adjustment of the transfer characteristics of the PAL-SLM and the LCD. Diffraction efficiency of 40% for binary phase grating and of 90% for 8-level blazed phase grating, which were very close to the simulation values, were observed. The power loss of the readout light was caused when passed through a half mirror, therefore, we examined a setup using an oblique readout light at the modulator. Very high diffraction efficiency was obtained from the setup by optimizing the polarization direction and optical path for this light, and the orientation of liquid crystals. Since the modulator can perform at better than 90% diffraction efficiency and at nearly 100% reflectivity, various high efficiency systems utilizing such modulators are expected.

Individual identification apparatus for selectively recording a reference pattern based on a correlation with comparative patterns

Abstract: The individual identification apparatus is provided for comparing a target pattern of an arbitrary person with a recorded reference pattern of a specific person, thereby judging whether the arbitrary person is the specific person. The apparatus has a calculation processing portion 60. In order to previously record a pattern of the specific person as a reference pattern, the portion 60 calculates correlations between the pattern of the specific person and comparative patterns which belong to other people. The portion 60 records the pattern of the specific person as a reference pattern only when the correlations between the pattern of the specific person and the comparative patterns are equal to or lower than a threshold. The portion 60 refuses to record, as a reference pattern, such a pattern that provides high correlations with regards to the other people's patterns and therefore that has a high similarity with regards to the other people's patterns. There is a small possibility that the apparatus will erroneously judge a match between an arbitrary person and the specific person when the arbitrary person is different from the specific person.

Selective image extraction by synthesis of the coherence function using two-dimensional optical lock-in amplifier with microchannel spatial light modulator

Abstract: A novel optical information processing system by synthesis of the coherence function is built up to extract a two dimensional image from a three-dimensional object at a tenable depth with neither mechanical scanning nor digital calculation. In this system, a two-dimensional optical lock-in amplifier with the microchannel spatial light modulator is developed to detect selectively the coherence component, so that the limitation to the depth resolution introduced by the holographic detection which was used in our previous systems is overcome. Selective image extraction Is demonstrated successfully.

Optical associatron: a simple model for optical associative memory

Abstract: A new neural network architecture for optical computing is proposed. This architecture can be used for implementing a simple system based on a modified theory of the associative memories. It is shown that the memorized patterns can be recalled perfectly by an experimental system using two microchannel spatial light modulators. The modified theory and principle of operation of the optical associatron system are discussed, and the system itself and basic experimental results are also described.

Femtosecond pulse shaping using spatial light modulators

Abstract: We review the field of femtosecond pulse shaping, in which Fourier synthesis methods are used to generate nearly arbitrarily shaped ultrafast optical wave forms according to user specification. An emphasis is placed on programmable pulse shaping methods based on the use of spatial light modulators. After outlining the fundamental principles of pulse shaping, we then present a detailed discussion of pulse shaping using several different types of spatial light modulators. Finally, new research directions in pulse shaping, and applications of pulse shaping to optical communications, biomedical optical imaging, high power laser amplifiers, quantum control, and laser-electron beam interactions are reviewed.

Information record infrastructure, system and method

Abstract: A method of maintaining digital medical records, comprising a step of receiving a medical transaction record (102), encrypted with a key in accordance with a patient-file association. Also comprising a step of accessing the encrypted medical transaction record according to a patient association with the record (111). And further comprising a step of re-encryption of the encrypted accessed medical transaction record with a key associated with an intended recipient of the medical record. The system and method according to the present invention presents a new business model for creation, maintenance, transmission, and use of medical records. The invention also allows financial burdens to be reallocated optimally and equitably, resulting in decreased overall societal cost and providing a successful business model for a database proprietor. Secure entrusted medical records are held in trust by an independent third party on behalf of the patient (113), and serve the medical community at large. Separately encrypted record elements may be aggregated as an information polymer.

System and method for secure three-party communications

Abstract: A system and method for communicating information between a first party and a second party, comprising the steps of receiving, by an intermediary, an identifier of desired information and accounting information for a transaction involving the information from the first party, transmitting an identifier of the first party to the second party, and negotiating, by the intermediary, a comprehension function for obscuring at least a portion of the information communicated between the first party and the second party. The data transmission may be made secure with respect to the intermediary by providing an asymmetric key or direct key exchange for encryption of the communication between the first and second party. The data transmission may be made secure with respect to the second party by maintaining the information in encrypted format at the second party, with the decryption key held only by the intermediary, and transmitting a secure composite of the decryption key and a new encryption key to the second party for transcoding of the data record, and providing the new decryption key to the first party, so that the information transmitted to the first party can be comprehended by it.

Adaptive pattern recognition based control system and method

Abstract: An adaptive interface for a programmable system, for predicting a desired user function, based on user history, as well as machine internal status and context. The apparatus receives an input from the user and other data. A predicted input is presented for confirmation by the user, and the predictive mechanism is updated based on this feedback. Also provided is a pattern recognition system for a multimedia device, wherein a user input is matched to a video stream on a conceptual basis, allowing inexact programming of a multimedia device. The system analyzes a data stream for correspondence with a data pattern for processing and storage. The data stream is subjected to adaptive pattern recognition to extract features of interest to provide a highly compressed representation that may be efficiently processed to determine correspondence. Applications of the interface and system include a video cassette recorder (VCR), medical device, vehicle control system, audio device, environmental control system, securities trading terminal, and smart house. The system optionally includes an actuator for effecting the environment of operation, allowing closed-loop feedback operation and automated learning.