LED for hyperspectral imaging – a new selection method

2018 ◽  
Vol 63 (5) ◽  
pp. 529-535 ◽  
Author(s):  
Tobias Heimpold ◽  
Frank Reifegerste ◽  
Stefan Drechsel ◽  
Jens Lienig
Keyword(s):  
Hyperspectral Imaging ◽  
Power Distribution ◽  
Spectral Power ◽  
Selection Process ◽  
Selection Method ◽  
Light Emitting ◽  
Spectral Power Distribution ◽  
Forward Current ◽  
Efficient Selection ◽  
Selection Of

AbstractHyperspectral imaging (HSI) has become a sophisticated technique in modern applications such as food analyses, recycling technology, medicine, pharmacy and forensic science. It allows one to analyse both spatial and spectral information from an object. But hyperspectral cameras are still expensive due to their extended wavelength range. The development of new light-emitting diodes (LED) in the recent past enables another approach to HSI using a monochrome camera in combination with a LED-based illumination. However, such a system has a lower spectral resolution. Additionally, the growing supply of LED on the market complicates the selection of LED. In this paper, we propose a new time efficient selection method for the design process of an illumination. It chooses an optimised LED combination from an existing database to match a predefined spectral power distribution. Therefore, an algorithm is used to evaluate various LED combinations. Furthermore, the method considers the spectral behaviour of each LED in dependence of forward current and temperature of the solder point. Our method has already shown promise during the selection process for even spectral distributions which is demonstrated in the study. Additionally, we will show its potential for HSI illuminations.

scholarly journals Influences of Spectral Power Distribution on Circadian Energy, Visual Comfort and Work Performance

2021 ◽  
Vol 13 (9) ◽  
pp. 4852
Author(s):  
Jack Ngarambe ◽  
Inhan Kim ◽  
Geun Young Yun
Keyword(s):  
Light Source ◽  
Power Distribution ◽  
Work Performance ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Essential Element ◽  
Visual Comfort ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Spectral Power Distribution

Spectral power distribution (SPD) is an essential element that has considerable implications on circadian energy and the perception of lit environments. The present study assessed the potential influences of SPD on energy consumption (i.e., considering circadian energy), visual comfort, work performance and mood. Two lighting conditions based on light-emitting diode (LED) and organic light-emitting diode (OLED) were used as proxies for SPDs of different spectral content: dominant peak wavelength of 455 nm (LED) and 618 nm (OLED). Using measured photometric values, the circadian light (CL), melatonin suppression (MS), and circadian efficacy (CE) of the two lighting sources were estimated via a circadian-phototransduction model and compared. Additionally, twenty-six participants were asked to evaluate the said lit environments subjectively in terms of visual comfort and self-reported work performance. Regarding circadian lighting and the associated energy implications, the LED light source induced higher biological actions with relatively less energy than the OLED light source. For visual comfort, OLED lighting-based conditions were preferred to LED lighting-based conditions, while the opposite was true when considering work performance and mood. The current study adds to the on-going debate regarding human-centric lighting, particularly considering the role of SPD in energy-efficient and circadian lighting practices.

Indoor Lighting Workplaces

2021 ◽  
pp. 243-258
Author(s):  
David Baeza Moyano ◽  
Roberto Alonso González Lezcano
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Working Environment ◽  
Office Work ◽  
Light Emitting ◽  
Spectral Power Distribution ◽  
Indoor Lighting ◽  
New Criteria

Office work has so far been carried out in company buildings and was largely based on the use of paper on a horizontal surface. Due to multiple reasons, more workers are working in their homes with electronic devices. As a result, both the working environment and personal tools are changing. Since the discovery about 20 years ago of the non-visual ways of light absorption, it was known that apart from the image forming effects (IF) of light from which the criteria for correct lighting have been developed, non-image forming effects (NIF) of light exist. The discovery of NIF has enhanced researcher belief in the importance of daylighting and has raised new criteria to be taken into account for proper interior lighting. Due to all the factors mentioned above, the parameters to be met by a luminaire and its environment for proper lighting of the workstation have been modified and expanded. The rapid advance in the development of new light-emitting diode (LED) luminaires with which the spectral power distribution (SPD) can be practically created opens the door to a genuine technological revolution comparable to the invention of electric lighting around 150 years ago. The authors of this study will review the latest published studies on the importance of light in our lives, IF and NIF effects of light, the parameters which from these effects are suggested to be taken into account for a correct indoor lighting, the regulations in force on indoor lighting workplaces, and proposals to improve indoor lighting and therefore the quality of life of workers.

scholarly journals LED LAMP FOR APPLICATION IN MEDICAL CENTERS – DESIGN AND THERMAL MANAGEMENT

2017 ◽  
Vol 3 ◽  
pp. 207
Author(s):  
Petko Mashkov ◽  
Hristo Beloev ◽  
Berkant Gyoch ◽  
Tamara Pencheva
Keyword(s):  
Circadian Rhythm ◽  
Power Distribution ◽  
Spectral Power ◽  
Experimental Studies ◽  
Spectral Composition ◽  
Light Sources ◽  
Artificial Lighting ◽  
Spectral Power Distribution ◽  
Medical Centers ◽  
Selection Of

The goal of this work is research and development of light sources suitable for use in hospitals, nursing homes, hospices and other similar institutions. During the day spectral power distribution (SPD) of this type luminaire needs to simulate natural day light that affects the natural circadian rhythm of humans. Maintaining the natural circadian rhythm impacts positive on human health, improves mood, prevents the development of depression and helps to overcome them. In the late afternoon increase light in the red-orange part. Light of this kind of spectral composition doesn’t inhibit melatonin production and the human body naturally prepares for rest and sleep. At night artificial lighting should be in the red - orange area to enable patients to sleep and staff to fulfill their obligations. Theoretical analysis and selection of suitable LEDs for the realization of the luminaire with the desired characteristics are made. Performed experimental studies make possible achieving the desired characteristics of light and appropriate LEDs’ modes of operation.

Modeling and Parametric Study of Light Scattering, Absorption and Emission of Phosphor in a White Light-Emitting Diode

2015 ◽  
Author(s):  
Jiaqi Wang ◽  
Jeffery C. C. Lo ◽  
S. W. Ricky Lee ◽  
Feng Yun ◽  
Mian Tao
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Optical Parameter ◽  
Optical Parameters ◽  
Peak Wavelength ◽  
Spectrum Prediction ◽  
Light Emitting ◽  
Spectral Power Distribution ◽  
Radiant Power

In this study, we proposed and demonstrated an effective approach to model and predict spectral power distribution (SPD) for a phosphor-converted light emitting diode (pc-LED). For emission and excitation, broadband diffuse transmittances of 1 mm YAG:Ce phosphor plates with different concentrations were measured by a spectrophotometer. For emission, it was found that transmittance for all wavelengths was almost identical. This result indicates that emission spectrum prediction could be simplified by simulating the radiant power of the peak wavelength only. At the peak wavelength (560 nm), our simulation results, in which optical constants were calculated by the Lorenz-Mie theory, agreed well with our measurements. For excitation, a novel transmittance measurement setup based on an LED goniophotometer was proposed to obtain the absorption coefficient. By adjusting the optical parameter in our ray-tracing model to fit measured transmittances, accurate absorption coefficients were determined. Based on our calculation and measured optical parameters, we simulated the radiant power of the blue light and yellow light of commercial white LED packages. By expanding the total blue and yellow power into linear combinations of wavelengths in both regions, we successfully predicted the SPD of our LED package. Our predicted SPD has good agreement with the measured results.

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