Illuminance Meter Research Articles

Quantifying the radiant exposure and effective dose in patients treated for actinic keratoses with topical photodynamic therapy using daylight and LED white light

Daylight photodynamic therapy (dl-PDT) is as effective as conventional PDT (c-PDT) for treating actinic keratoses but has the advantage of reducing patient discomfort significantly. Topical dl-PDT and white light-PDT (wl-PDT) differ from c-PDT by way of light sources and methodology. We measured the variables associated with light dose delivery to skin surface and influence of geometry using a radiometer, a spectral radiometer and an illuminance meter. The associated errors of the measurement methods were assessed. The spectral and spatial distribution of the radiant energy from the LED white light source was evaluated in order to define the maximum treatment area, setup and treatment protocol for wl-PDT. We compared the data with two red LED light sources we use for c-PDT. The calculated effective light dose is the product of the normalised absorption spectrum of the photosensitizer, protoporphyrin IX (PpIX), the irradiance spectrum and the treatment time. The effective light dose from daylight ranged from 3 ± 0.4 to 44 ± 6 J cm−2due to varying weather conditions. The effective light dose for wl-PDT was reproducible for treatments but it varied across the treatment area between 4 ± 0.1 J cm−2 at the edge and 9 ± 0.1 J cm−2 centrally. The effective light dose for the red waveband (615–645 nm) was 0.42 ± 0.05 J cm−2 on a clear day, 0.05 ± 0.01 J cm−2 on an overcast day and 0.9 ± 0.01 J cm−2 using the white light. This compares with 0.95 ± 0.01 and 0.84 ± 0.01 J cm−2 for c-PDT devices. Estimated errors associated with indirect determination of daylight effective light dose were very significant, particularly for effective light doses less than 5 J cm−2 (up to 83% for irradiance calculations). The primary source of error is in establishment of the relationship between irradiance or illuminance and effective dose. Use of the O’Mahoney model is recommended using a calibrated logging illuminance meter with the detector in the plane of the treatment area.

Toward proper evaluation of light dose in indoor office environment by frontal lux meter

The wearable Brazilian illuminance meter “OcuLux” provides the opportunity to monitor continuously pupilar illuminance for indoor environment. The device is calibrated to evaluate the illuminance in lux for the range of 0 to 3500 lux with 23% of precision. This sensor was worn for 19 days in an office room of the LESO solar experimental building at EPFL (Lausanne, Switzerland), equipped with Anidolic Daylighting System (ADS) as well as a conventional window, to assess the light dose received by a human subject (30 year old female). The results showed that: i) the light dose is lower than the recommended values for most of the time; ii) in spite of asymmetrical workstation orientation, the light dose received during the morning and in the afternoon are comparable and iii) the impact of day length and sky condition on the light dose at the pupillary level is considerable.

Brightness Uniformity Evaluation of the LED Planar Light Source using a Illuminometer

We used an illuminance meter in order to evaluate brightness uniformity of a LED planar light source inexpensively and compared with the value measured by a luminance meter. We selected two different LED planar light sources: direct-type and edge-type. The measured uniformity of edge-type is more than 0.95 irrespective of the aperture size. However, the uniformity of direct-type LED source is measured differently for aperture size. Since the uniformity of direct-type is affected by the pixel size, the pixel size should be considered in evaluating uniformity. Both the luminance meter and the illuminance meter(combined the barrel and the aperture) showed similar pattern in uniformity and the standard deviation. By improving the aperture and the barrel, the illuminance meter can measure brightness uniformity with to the luminance meter at low cost.

Performance measurement of a smoke extraction system for buildings in full-scale hot smoke test

Abstract The current inspection method for a smoke extraction system in Taiwan measures whether the air flow of the smoke vent conforms to the design value. However, this method is inapplicable to natural smoke extraction systems. As the plugholing effect is disregarded, adequate air flow cannot ensure that the system will exhaust smoke effectively during a fire. Hence, a full-scale hot smoke test for smoke extraction systems is necessary. Some international test criteria are formulated using visible smoke and alcoholic fuel which is pollution-free after combustion. The effectiveness is judged only by visually observing the smoke’s flow direction, which is indeed unscientific. This study used a string of vertical smoke layer measuring instruments composed of several approved photoelectric smoke detectors, as well as a light attenuation measuring device composed of illuminance meters to conduct tests on the effect of makeup air. The results proved that the former one uses different height induction times to judge the position of the smoke layer effectively, while the latter one uses the light attenuation rate to distinguish the smoke density instantly and accurately. The obtained experimental data were consistent with the onsite smoke distribution. The two sets of equipment designed in this study can be used for full-scale hot smoke tests to obtain performance data for a smoke extraction system.

Reflections on light monitoring: Evaluating museum lighting options for modern and contemporary art

Spectrometric handheld light meters that can provide adequate data for evaluation of replacement bulbs for contemporary art objects are now commercially available. This approach was taken to assess potential replacements for the incandescent street lamps in Chris Burden's Urban Light at LACMA, Los Angeles, USA. These meters are also useful tools for monitoring and characterizing museum lighting, which are currently done with illuminance (lux) meters. The new spectral light meters will enable conservators to tailor lighting recommendations for individual artworks, when spectral information from these meters is combined with damage function data on artists’ materials. The latter information can be obtained for some materials by a small modification to the microfade testing procedure, as exemplified by microfading colored samples Henri Matisse created during the design phase for La Gerbe.

Light diffuseness metric, Part 2: Describing, measuring and visualising the light flow and diffuseness in three-dimensional spaces

We introduce a way to simultaneously measure the light density, light vector and diffuseness of the light field using a cubic illumination meter based on the spherical harmonics representation of the light field. This approach was applied to six light probe images of natural scenes and four real scenes built in our laboratory, and the results were compared to those obtained using Cuttle’s method. We also demonstrated a way to simultaneously and intuitively visualise the global structure of the light distribution using light tubes and colour coding for the light density, light flow and diffuseness variations through the space. Together with Mury’s work, we have a complete way to describe, measure and visualise the local and global low-order properties of light distributions in three-dimensional spaces.

Testing of Illuminance Meters

If researchers measure illuminance with illuminance meters, they should apply meters appropriate quality, with known accuracy and type of uncertainties. Therefore the test measurements should be performed before carrying out experiments. Illuminance measurements applied in research require using calibrated photometric heads because sensors measure various illuminance levels due to degradation in time. Accuracy of every measurement is influenced by errors of instrument construction and of measuring procedure. During preparation of experiment and its carrying out should be these errors reduced at the most. This paper discusses influence of illuminance quality, importance of the photometric heads calibration on the Daylight Factor measurements.

Design of a CMOS Calibrated Monolithic Illumination Meter for Monitoring Solar Radiation of Tomato Crops

In this paper, a complementary metal–oxide–semiconductor (CMOS) calibrated monolithic illumination meter for monitoring solar radiation of tomato crops is newly proposed. The output signal is a pulse stream, it could be easily sent over a wide range of transmission media, such as package switch network, radio, optical, infrared, ultrasonic, and so on. Another innovation is that the proposed calibration method can reduce the nonlinear error arising from sun sensors. By collocating with a monolithic sun sensor, which has a radiation range of 68.9–188.7 W/m2, the corresponding output frequency ranges from 0.7 to 1.82 MHz. After calibration, a measured maximum frequency error is 1.63%. Measurement results have successfully verified all the functions and performance of the proposed calibrated monolithic illumination meter and confirmed it to be applied on monitoring solar radiation of tomato crops. The proposed CMOS calibrated monolithic illumination meter is suitable for measuring solar radiation devices, such as the devices for detecting solar radiation of crops.

Effects of seasonal illumination and thermal environments on sleep in elderly men

The purpose of this study was to investigate the effect of changes in the seasonal thermal environment and illuminance on sleep in older men by using actigraphy. Eight healthy male volunteers with a mean age of 64 ± 1 years served as subjects. The measurements were obtained in 4 consecutive seasons: spring, summer, autumn, and winter. The activity level and illuminance were monitored using a wrist actigraph system with illuminance meter for 5 consecutive days. Sleep parameters were determined using an actigraph-based, sleep-wake identification algorithm. The temperature and humidity in the bedroom of the subjects' homes were measured continuously for 5 days. During the actigraphic measurement, skin temperature and the temperature and humidity of the microclimate were measured continuously for 2 nights. Bedroom nocturnal Ta and humidity was significantly higher in the summer than in the other seasons. Sleep efficiency was worst in the summer due to the increased number and duration of nocturnal awakenings. However, a significant difference was not found in the subjective evaluation of sleep among the 4 seasons. The correlations between the sleep parameters and environmental factors such as temperature, humidity, and illuminance levels measured at the same time showed that increased lighting level before the sleep prolongs the bedtime and wake time after sleep onset, and became wake-up time earlier. Increased ta, humidity, and lighting level during the sleep period mount up the wake time after sleep onset and impaired the sleep efficiency index.

Influence of Instantaneous Measured Data on Evaluation Interval of Daylighting

Daylight varies during daytime and it is an important health aspect of indoor visual environmental quality. Measurements of daylighting are very complicated in natural conditions, therefore processing and evaluation of measured date requires special care. The instantaneous illuminances in one room and outside in Bratislava with 5 second time step were measured by two illuminance meters with data loggers. The first illuminance meter registered indoor illuminance and was placed on the level of the working plane inside the room in its centre. The second illuminance meter with an unscreened sensor was placed on the roof and measured exterior global horizontal illuminance. Daily illuminance courses derived from 5 sec instantaneous data and 1 min and 1 hour averages were inspected and evaluated. This paper presents results of evaluations of real measurements and the discussion focus on the influence of evaluation interval on the accuracy of daily illuminance courses.

A mobile complex for on-line studying water areas and surface atmosphere

The complex is intended to perform continuous measurements of concentrations of chlorophyll a and dissolved organic substances by the laser induced fluorescence method, evaluate a state of the photosynthetic system of phytoplankton cells, and record readings of the CO2 gas analyzer, sensors of sea water saltiness, pH, and temperature, and solar illumination meter. The mobility of the complex ensures a possibility of its operation on different ships and under stationary conditions. The configuration of the complex can be promptly changed for solving the current problem by promptly adding or replacing separate devices and sensors of the complex, as well as the software integrating all devices and data into the system. It is possible to use standard, vibration-resistant laboratory equipment, since the housing of the designed device ensures protection against the marine environment. Results of in-situ measurements performed in the Peter the Great Gulf (Sea of Japan) in 2012 are given.

Abstracts from the 28th Annual Meeting of the Engineering and Urology SocietyMay 4, 2013San Diego, CA

Abstracts from the 28th Annual Meeting of the Engineering and Urology SocietyMay 4, 2013San Diego, CA

The effect of ambient illumination on handheld display image quality.

Handheld devices such as smartphones and tablets are becoming useful in the medical field, as they allow physicians, radiologists, and researchers to analyze images with the benefit of mobile accessibility. However, for handheld devices to be effective, the display must be able to perform well in a wide range of ambient illumination conditions. We conducted visual experiments to quantify user performance for testing the image quality of two current-generation devices in different ambient illumination conditions while measuring ambient light levels with a real-time illuminance meter. We found and quantified that due to the high reflectivity of handheld devices, performance deteriorates as the user moves from dark areas into environments of greater ambient illumination. The quantitative analysis suggests that differences in display reflection coefficients do not affect the low illumination performance of the device but rather the performance at higher levels of illumination.

Comparison of Optics and Performance of a Distal Sensor High Definition Cystoscope, a Distal Sensor Standard Definition Cystoscope, and a Fiberoptic Cystoscope

To evaluate performance characteristics and optics of a new generation high-definition distal sensor (HD-DS) flexible cystoscope, a standard-definition distal sensor (SD-DS) cystoscope, and a standard fiberoptic (FO) cystoscope. Three new cystoscopes (HD-DS, SD-DS, and FO) were compared for active deflection, irrigation flow, and optical characteristics. Each cystoscope was evaluated with an empty working channel and with various accessories. Optical characteristics (resolution, grayscale imaging, color representation, depth of field, and image brightness) were measured using United States Air Force (USAF)/Edmund Optics test targets and illumination meter. We digitally recorded a porcine cystoscopy in both clear and blood fields, with subsequent video analysis by 8 surgeons via questionnaire. The HD-DS had a higher resolution than the SD-DS and the FO at both 20 mm (6.35 vs 4.00 vs 2.24 line pairs/mm) and 10 mm (14.3 vs 7.13 vs 4.00 line pairs/mm) evaluations, respectively (P <.001 and P <.001). Color representation and depth of field (P = .001 and P <.001) were better in the HD-DS. When compared to the FO, the HD-DS and SD-DS demonstrated superior deflection up and irrigant flow with and without accessory present in the working channel, whereas image brightness was superior in the FO (P <.001, P = .001, and P <.001, respectively). Observers deemed the HD-DS cystoscope superior in visualization in clear and bloody fields, as well as for illumination. The new HD-DS provided significantly improved visualization in a clear and a bloody field, resolution, color representation, and depth of field compared to SD-DS and FO. Clinical correlation of these findings is pending.

Spectral responsivity-based calibration of photometer and colorimeter standards

Several new generation transfer- and working-standard illuminance meters and tristimulus colorimeters have been developed at the National Institute of Standards and Technology (NIST) [1] to measure all kinds of light sources with low uncertainty. The spectral and broad-band (illuminance) responsivities of the photometer (Y) channels of two tristimulus meters were determined at both the Spectral Irradiance and Radiance Responsivity Calibrations using Uniform Sources (SIRCUS) facility and the Spectral Comparator Facility (SCF) [2]. The two illuminance responsivities agreed within 0.1% with an overall uncertainty of 0.2% (k = 2), which is a factor of two improvement over the present NIST photometric scale. The first detector-based tristimulus color scale [3] was realized. All channels of the reference tristimulus colorimeter were calibrated at the SIRCUS. The other tristimulus meters were calibrated at the SCF and also against the reference meter on the photometry bench in broad-band measurement mode. The agreement between detector- and source-based calibrations was within 3 K when a tungsten lamp-standard was measured at 2856 K and 3100 K [4]. The color–temperature uncertainty of tungsten lamp measurements was 4 K (k = 2) between 2300 K and 3200 K, which is a factor of two improvement over the presently used NIST source-based color temperature scale. One colorimeter was extended with an additional (fifth) channel to apply software implemented matrix corrections. With this correction, the spectral mismatch caused color difference errors were decreased by a factor of 20 for single-color LEDs.

Surface Characteristics of Anodized AZ91D with Potassium Permanganate in Alkaline by Various Time

Magnesium is demanded increasing in aerospace, electronics industry and medical field requires the surface treatment method. That allows increasing the corrosion resistance in order to put to practical use as products. The spark anodized treatment method in this study used was anodized depending on the various times to 1-4 minutes with a current density of 300 mA/cm2 in the constant-current mode that duty cycle is 50% and frequency is 125 Hz by a bipolar pulse power. And the characteristics of the film were evaluated. This treatment method is to obtain the uniform film by reducing the applied voltage on the surface by adding 0.1 M Sodium silicate (Na2SiO3) in the mixed solution of 2.0 M Sodium hydroxide (NaOH) and 0.1M Sodium phosphate (Na3PO4). It aims to express brown or dark brown color by adding Potassium permanganate, and to improve the corrosion resistance. After anodization treatment, the surface characteristics were analyzed using SEM, XRD and illuminance meter, and Vickers hardness was measured. In order to evaluate of corrosion resistance, the corrosion potential and corrosion current were measured by potentiodynamic method in 3.5 wt. % NaCl electrolyte. The critical voltage required to generate the oxidized layer could be lower depending on the addition of (Na2SiO3) and (KMnO4). The size of a pore was reduced depending on the processing time, and the thickness of the film was grown in proportion to it. As the result of XRD, a new peak of Mg0.9Mn0.1O was formed, and the peak of parent metal was reduced by the increase of the oxide. By the potentiodynamic polarization behavior, the value of corrosion potential was increased and the corrosion current density was decreased and the corrosion resistance was improved.

Quantifying the impact of road lighting on road safety — A New Zealand Study

It is well known from the literature that road lighting has significant safety benefits. The NZTA Economic Evaluation Manual (EEM) quotes a 35% reduction in crashes as the effect of upgrading or improving lighting where lighting is poor.However, no well-established dose–response relationship to lighting parameters exists from which one can deduce benchmark levels of lighting for safety.This study looked at a sample of street lighting installations spread over the urban areas of nine territorial local authorities. Standard street lighting parameters were measured in the field using a variety of instruments including illuminance meter, luminance meter and digital camera. Field measurements were related to the ratio of night-time to day time crashes as a measure of night time safety vis-a-vis daytime safety.A statistically significant dose–response relationship was found between average road luminance and safety across all traffic volume groups, with an indication that the relationship may be stronger where more serious crashes are involved.Threshold increment was also a significant variable but not so longitudinal uniformity or overall uniformity.The results related to luminance will allow practitioners to better estimate the safety benefits of different levels of lighting resulting in better targeting of expenditure.

Testing and Analysis of Intensity of Illumination of Manual Assembly Workbench Surface

the manual assembly line used for assembling a certain type of lighting panel was introduced. The manual assembly works were analyzed. The assembly workbench surface illumination of the assembly line was tested. According to the light source is linear form, the assembly workbench surface was divided into some rectangles firstly. The intensity of illumination of these rectangles centers were tested by the illuminance meter. The average illuminance was also calculated out. According to these values, the illuminance curves were draw, which were approximately parallel lines. Further, the time values of the workers complete the same assembly work in different illumination were measured. The analysis reveals that the high illumination or the low level of illumination will affect the work efficiency. The reasonable illumination interval values were found. The testing and analysis provide scientific basis for the adjustment of the workbench illuminance and the improvement of working environment lighting.

Error Analysis of the Illuminance Meter Verification System

In illuminance meter verification system, there are many factors that affect verification accuracy. If we can reduce or avoid these factors, the verification system will improve verification accuracy to meet research needs and customer requirements. This paper analyzes the factors in detail during the testing process, such as positioning accuracy and voltage fluctuation. It will help to provide theoretical basis for the future system improvements.

Detector-Based Calibration for Illuminance and Luminance Meters—Experimental Results

The connection between illuminance and luminance measurements is considered to create a traceability link among a highly accurate illuminance meter, which is considered as an internal standard of the Photometric Laboratory, University of Padova, Padova, Italy, and other illuminance meters or photometric heads and luminance meters. After an introduction on the main involved definitions and equations linking the illuminance and the luminance measurements, this paper presents the instruments to which the procedures are applied and, at the end, results regarding the absolute calibration of the instruments under test, the check of their linearity, and the analysis of their spectral responsivity within the visible range. Following this way, this paper shows the main results in the connection among instruments devoted specifically to illuminance and luminance measurements. Then, it also introduces a comparison to other photometric heads, e.g., sensors that are part of more complex systems, like an integrating sphere for luminous flux measurement. In this last case, it has no significance to evaluate the difference between the absolute outputs, but it is interesting to compare the response of the two devices considering their linearity and their relative spectral response. A special section devoted to the evaluation of the spectral response presents a new simple but effective method. The application of a detector-based method allows a significant reduction of the uncertainty in the internal calibration of the photometric instruments, granting the continuity of the Photometric Laboratory operation contemporarily.