A simple experiment to measure the inverse square law of light in daylight conditions

Vera, Francisco; Rivera, Rodrigo; Ortíz, Manuel

doi:10.1088/0143-0807/35/1/015015

Cited by 15 publications

(10 citation statements)

References 2 publications

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“…As the lightbox provided therapy at the bedside, patients can freely change their position in bed or adjust the bedframe angle to dull their bright light exposure. Patients who are outside the lightbox’s therapeutic range risk diluting the intended high-intensity light exposure needed to elucidate any biological effect BLT may have [ 21 ]. It is possible that unsuccessful application of the intervention accounts for the lack of difference seen between cohorts.…”

Section: Discussionmentioning

confidence: 99%

Prospective Randomized Controlled Pilot Study of High-Intensity Lightbox Phototherapy to Prevent ICU-Acquired Delirium Incidence

Zhang¹,

Pelleg²,

Hussain³

et al. 2021

Cureus

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Background This study aimed to evaluate the role of disturbed circadian rhythm in potentiating intensive care unit (ICU)-acquired delirium.Previous studies have demonstrated bright light therapy (BLT) as an effective modality to improve sleeping patterns and cognitive function in non-critically ill patients. However, its benefit in the ICU has not been clearly established. In this study, we aimed to evaluate the application of daily high-intensity phototherapy at the bedside to deter ICU delirium incidence and duration. Methodology This was a single center, prospective study conducted in ICUs at the Carilion Roanoke Memorial Hospital in Roanoke, VA. Adults patients admitted to the ICU from July 9, 2018 to March 20, 2020 were included in the study. The patients were subjected to 30-minute BLT session (10,000 lux) at the bedside starting at 0700 while in the ICU. Patients were randomized into either the control group (standard hospital lighting) or phototherapy group. Data were analyzed using Wilcoxon rank sum test for continuous variables, Pearson chi-square test for categorical variables, and logistic regression for multivariable analysis that examined significant risk factors for ICU delirium. Results Delirium incidence between BLT (18%) and control (17.5%) groups was non-significant. Total number of delirium-free, coma-free days, as determined by Confusion Assessment Method for the ICU, demonstrated no differences between groups with a median of 28 days (p = 0.516). In multivariable analysis, patients with a Sequential Organ Failure Assessment Score >3 also showed no significant change in ICU delirium incidence when provided bedside BLT compared to those with standard hospital lighting (odds ratio: 0.08; 95% confidence interval: 0.002-1.40; p = 0.867). Conclusions In this randomized control pilot study, daily morning 10,000 lux BLT of 30-minute duration alone was not associated with a significant decrease in ICU-acquired delirium incidence or duration compared to standard hospital lighting. Future studies should consider a nuanced approach to better elucidate the role of disturbed circadian rhythm in influencing ICU-acquired delirium by not only undertaking BLT during the day but also minimizing nighttime light exposure.

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Section: Discussionmentioning

confidence: 99%

Prospective Randomized Controlled Pilot Study of High-Intensity Lightbox Phototherapy to Prevent ICU-Acquired Delirium Incidence

Zhang¹,

Pelleg²,

Hussain³

et al. 2021

Cureus

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“…However, at a far enough distance, the LED illuminance will be diffused with that of the surrounding environment, causing incorrect measurement. Therefore, the illuminance of the LED operates at maximum power at a distance of 1cm (E max LED (1) ) will first be measured, and the maximum illuminance at any other distance will be calculated according to the formula of the inverse square law [18]:…”

Section: Figure 3 Experiments Stepsmentioning

confidence: 99%

A low-cost IoT - enabled smart lighting system for energy efficiency in domestic use

2023

jsthaui

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Regarding current domestic lighting systems, there are two development pathways: the first is integrating Internet of Things (IoT) technology for the convenience and comfortability of users, and hence, enhancing the quality of life. The second one is pushing for a more energy-efficient lighting system to reduce energy consumption, which is a crucial task in the ongoing struggle against climate change. This research addresses these two problems by developing a lighting system that will automatically adjust the light's intensity in domestic use based on the surrounding environment condition to achieve high energy efficiency. A low-cost intelligent lighting instrumentation and automation system are developed based on IoT technology. The system collects and stores environmental data on the cloud, as well as being able to remotely control via the Internet and voice controllable by virtual assistance. This can be conducted by utilising light sensors, an Arduino-based microcontroller, and a cloud platform to facilitate communication between elements of the system.. An experiment will then be conducted to demonstrate that the proposed system can achieve energy-saving in comparison to a conventional scheme.

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“…It can be seen from Eq. 6 that irradiance from a point source has both inverse square law relationship [ 13 , 25 ] and cosine dependence [ 13 , 23 ]. Since radiant intensity remains same in all directions, hence Eqs.…”

Section: Mathematical Modelingmentioning

confidence: 99%

Theoretical Simulation for Evaluating Error in Irradiance Measurement Using Optical Detectors Having Different Cosine Responses

Vijeta

Kapri

Saha

et al. 2021

MAPAN

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Cosine response is an important characteristic of an optical detector for irradiance measurements. The non-ideal cosine response of a detector may lead to errors in irradiance measurements. In this paper, a theoretical simulation of irradiance generated due to isotropic point light sources is carried out for different illumination conditions. Simulation results show that the errors in irradiance measurements due to the cosine error of detectors become significantly high at the edges and corners of the floor when a light source is placed at the center of the roof. Further, it is observed that the errors are more in the enclosures having a height smaller than the floor dimensions. Even calibrated detectors measure erratic values of irradiance for a wider angle of incidence. Therefore, cosine errors in irradiance measurements are of great importance especially during the current scenarios of the COVID-19 pandemic, for ensuring the correct dose of Ultraviolet Germicidal Irradiation (UVGI).

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A simple experiment to measure the inverse square law of light in daylight conditions

Cited by 15 publications

References 2 publications

Prospective Randomized Controlled Pilot Study of High-Intensity Lightbox Phototherapy to Prevent ICU-Acquired Delirium Incidence

Prospective Randomized Controlled Pilot Study of High-Intensity Lightbox Phototherapy to Prevent ICU-Acquired Delirium Incidence

A low-cost IoT - enabled smart lighting system for energy efficiency in domestic use

Theoretical Simulation for Evaluating Error in Irradiance Measurement Using Optical Detectors Having Different Cosine Responses

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