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Chang C.-C.,National Taipei University of Technology | Chen C.-C.,National Taipei University of Technology | Kurokawa U.,NanoLambda, Inc. | Choi B.I.,NanoLambda, Inc.
IEEE Sensors Journal | Year: 2011

As a variety of light-emitting diode (LED) applications rapidly develops, accurate specifications of LED characteristics are increasingly important. In this work, we present a method for accurate measurement of LED spectra using a novel low-cost filter-array spectrum sensor. The measurement accuracy is further enhanced using particle swarm optimization. As a result, the proposed sensing method not only matches the performance of a professional optical spectrometer, but also is suitable for low-cost consumer applications, wherever the precise spectrum (or color) measurement is demanded. © 2011 IEEE.


Kurokawa U.,NanoLambda, Inc. | Choi B.I.,NanoLambda, Inc. | Chang C.-C.,National Taipei University of Technology
IEEE Sensors Journal | Year: 2011

Miniature spectrometers provide a cost and size advantage over traditional spectrometers. However, unlike traditional spectrometers in which appropriate dispersive optics and/or interferometric devices are well-developed, miniature spectrometers usually do not have ideal (or close to ideal) wavelength-specific filtering mechanism to resolve the power of the input spectrum at specified wavelengths. Hence, the raw outputs from the filtering mechanism may not be adequate to represent spectra of measured objects. The nonideal filtering mechanism makes reconstruction process necessary. In this work, the method of Tikhonov regularization for stabilizing the solution of inverse problems is applied to a prototype filter-based nano-optic spectrum sensor from nanoLambda. L-curve criterion and generalized cross validation (GCV) criterion for adaptively selecting the regularization parameter are examined. Satisfactory results are obtained by exploiting non-negative constraints on the reconstructed spectrum, with the regularization parameter being selected by the L-curve criterion. As a result, low-cost miniature spectrometer on-a-chip can be realized. © 2010 IEEE.


Chang C.-C.,National Taipei University of Technology | Chen C.-C.,National Taipei University of Technology | Kurokawa U.,NanoLambda, Inc. | Choi B.I.,NanoLambda, Inc.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Peak wavelength and full-width-half-maximum (FWHM) are the two important parameters to characterize the spectra of monochromatic LED lights. In this work, a low-cost miniature filter-array spectrum sensor for accurate LED measurement is proposed. For mapping the data from the outputs of the filter-array spectrum sensor to the measurement parameters of peak wavelength and FWHM, Gaussian curves are used as the basis functions to facilitate the estimation. In addition, particle swarm optimization (PSO) is utilized for searching the optimal center locations and the widths of the Gaussian basis functions. The resulting measurement accuracy is competitive to a professional optical spectrometer. © 2011 SPIE.


Chang C.-C.,National Taipei University of Technology | Su Y.-J.,National Taipei University of Technology | Kurokawa U.,NanoLambda, Inc. | Choi B.I.,NanoLambda, Inc.
IEEE Sensors Journal | Year: 2012

With the recent development of solid-state lighting (SSL) technologies, visible light communication (VLC) systems using light-emitting diodes (LEDs) has been a promising technology to complement wireless communication. While LEDs offers advantageous properties such as high brightness, lower power consumption, long lifetime, and short transient time for high transmission rates, few researches have been exploited on the receiver side. Conventionally, photoelectric-diodes are implemented to convert optical signals into electronic signals. Since conventional photoelectric-diodes cannot distinguish inputs of different spectra, using conventional photoelectric-diodes have the disadvantage that the system is vulnerable to interference, and that it is hard to achieve wavelength-division-multiplexing (WDM) for light sources of different wavelengths. In this work, a spectrum sensor array is proposed to be implemented on the receiver side to achieve interference rejection. Due to recent advances in semiconductor technologies, spectrum sensors with different spectral transmission properties can be integrated into a chip-scale sensor-array. By proper design of the weightings for individual spectrum sensor, the effective output signal-to-interference ratio (SIR) can be maximized. Following the concept of coherent multi-antenna communication systems, signal fusion algorithms are presented. Our simulation is conducted based on the specification of a prototype filter-array spectrum sensor from nanoLambda. Simulation results demonstrate that robust interference rejection is possible using the low-cost spectrum sensor array. © 2001-2012 IEEE.


Chang C.-C.,National Taipei University of Technology | Su Y.-J.,National Taipei University of Technology | Kurokawa U.,NanoLambda, Inc. | Choi B.I.,NanoLambda, Inc.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

The visible light communication (VLC) systems using light emitting diodes (LEDs) has been a promising transmission technology to complement wireless communications. In this work, a spectrum sensor array is proposed to be implemented on the receiver side. Following the concept of multi-antenna communication systems, signal fusion algorithm is presented. By proper design of the weighting for each individual spectrum sensor, the effective output signal to interference ratio (SIR) can be maximized and hence make interference rejection possible. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).


Patent
NanoLambda, Inc. | Date: 2012-09-07

A spectrum sensing method includes (a) receiving an incident radiation simultaneously through a filter array composed of multiple bandpass filters, (b) digitizing spectral responses of the filter array, and (c) generating an estimate of spectral profile of the incident radiation based on digitized spectral responses of the filter array.


Patent
NanoLambda, Inc. | Date: 2010-03-19

A device such as a filter or reflector includes a conductive layer including a periodic pattern of elements. The elements have shapes and sizes configured such that a transmittance or reflectance spectrum of the conductive layer has a drop at a long-wavelength end. The elements have a period configured such that the spectrum has a dip at a Plasmon mode resonant wavelength. The spectrum further includes a peal- between the dip and the drop.


Patent
NanoLambda, Inc. | Date: 2011-09-22

Miniature spectrometers produce low resolution spectral data due to their size limitations. A method for processing these spectral data is proposed. The spectral data from a low resolution spectrometer is enhanced to a higher resolution, or processed to be in the wavelength domain. This process is called spectrum reconstruction, and can be used in low cost and miniature spectrometers with limited spectral resolution. The proposed method is noise robust, adapts to input spectrum, and can be used across many types of spectrometric devices without any manual adjustment of parameters.


Grant
Agency: National Science Foundation | Branch: | Program: STTR | Phase: Phase II | Award Amount: 100.00K | Year: 2011

NanoLambda, Inc has requested support for a one year membership to the Agile Innovation System that was recently selected as the recipient of the Economic Development Administrations Region 1 i6 award. In collaboration with the "Agile Innovation Process" project team, this proposal will complete the monolithic fabrication of the nano-optic filter array structure directly onto the CMOS detector array on a wafer scale, to form a spectrometer-on-a-chip. The proposed ultra-compact and low-cost spectrometer-on-a-chip can be used in various applications such as mobile/wearable health monitoring and high-resolution color sensing. As part of a winning team for the i6 Challenge Award program, Innovation Works and Carnegie Mellon University will collaborate with NanoLambda to more effectively move federally funded research towards successful technology product commercialization. The proposed ultra-compact and low-cost spectrometer-on-a-chip can be used in various applications such as mobile/wearable health monitoring and high-resolution color sensing. Consumer electronics manufacturers and portable medical device vendors can be potential customers. Considering the manufacturability of the proposed technology and the readiness of the markets, it is feasible to commercialize the technology within 2 years. The proposed activities will contribute to not only ensuring the high quality of color in the consumer electronics industry but also advancing personalized point-of-care, environmental monitoring, and homeland security. The proposed project will also contribute to the maturation of the "Agile Innovation Process" project of the i6 challenge winning team in the region.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: STTR PHASE II | Award Amount: 100.00K | Year: 2011

NanoLambda, Inc has requested support for a one year membership to the Agile Innovation System that was recently selected as the recipient of the Economic Development Administrations Region 1 i6 award.

In collaboration with the Agile Innovation Process project team, this proposal will complete the monolithic fabrication of the nano-optic filter array structure directly onto the CMOS detector array on a wafer scale, to form a spectrometer-on-a-chip. The proposed ultra-compact and low-cost spectrometer-on-a-chip can be used in various applications such as mobile/wearable health monitoring and high-resolution color sensing.

As part of a winning team for the i6 Challenge Award program, Innovation Works and Carnegie Mellon University will collaborate with NanoLambda to more effectively move federally funded research towards successful technology product commercialization.

The proposed ultra-compact and low-cost spectrometer-on-a-chip can be used in various applications such as mobile/wearable health monitoring and high-resolution color sensing. Consumer electronics manufacturers and portable medical device vendors can be potential customers. Considering the manufacturability of the proposed technology and the readiness of the markets, it is feasible to commercialize the technology within 2 years. The proposed activities will contribute to not only ensuring the high quality of color in the consumer electronics industry but also advancing personalized point-of-care, environmental monitoring, and homeland security. The proposed project will also contribute to the maturation of the Agile Innovation Process project of the i6 challenge winning team in the region.

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