Luminance Measurements Research Articles

The Photometric Testing of High-Resolution Digital Cameras from Smartphones—A Pilot Study

Luminance is the fundamental photometric quantity representing the technical meaning of brightness. It is usually measured from a distance using a matrix sensor, which is the basis of the professional instrument. However, specific technical requirements must be fulfilled to achieve accurate results. This paper considers whether modern high-resolution smartphone cameras are suitable for luminance measurements. Three cameras from high-end smartphones were evaluated on a dedicated laboratory stand. The sensors’ output characteristics showed relatively good linearity of the individual R, G, and B channels. Unfortunately, the spectral sensitivities were unfavorable, as the minimum error achieved was about 17%. This device is classified outside the generally accepted quality scale for photometric instruments. The presented investigation confirmed that none of the high-resolution smartphone cameras tested was suitable for use as a universal luminance camera. However, one of the test devices can be developmental if restrictively calibrated and used only in a specialistic laboratory stand. Using a smartphone (or only its camera) for luminance measurements requires proper advanced calibration. It is possible, but it limits us to only dedicated applications. The pilot study presented in this paper will help create a suitable test stand for spectacle vision systems, e.g., virtual reality equipment.

Characterization of developed integrating sphere photometer system for total luminous flux measurements

This research focuses on characterizing a developed integrating sphere photometer system for measuring total luminous flux at the National Institute of Standards (NIS) in Egypt. The research examines factors such as the efficiency of the integrating sphere across different wavelengths, the sphere photometer calibration factor (SPCF), and temperature variations in the photometer system during measurement days. One setup utilizes a spectroradiometer with an uncertainty of 4.7% and a 2.5-meter integrating sphere to measure the spectral responsivity of the sphere photometer. Another setup involves a 2.5-meter big-integrating sphere and NIS-photometer, along with NIS- luminous flux standard lamps calibrated at (NPL) with an uncertainty of 0.8%, to determine the SPCF. The overall uncertainty of the final (SPCF) ranges from 0.03% to 0.05%, while the temperature variation during measurements ranges from 0.045% to 0.07%.

Daylighting Through Electrochromic Glazing Under Overcast Skies: Impacts on Visual Task Performance and Perception

ABSTRACT Electrochromic (EC) glazing allows modulating the intensity of visual and solar transmission by dynamically switching between bleached (clear) and tinted (colored) states, leading to changes in spectral power distribution (SPD), correlated color temperature (CCT), and illuminance of the incoming daylight. In this experimental study, we investigated the impact of spectral composition of daylight filtered through a 6-pane EC façade on visual task performance and visual perception. In a semi-controlled test room, 19 subjects were exposed to five setting scenarios of the EC façade (fully bleached, mixed setting after fully bleached, fully tinted, mixed setting after fully tinted, and user-controlled). Test subjects performed a series of visual tasks, and their assessments of the indoor environment and of the outside view were collected along with luminous and spectral measurements under each condition. The analysis provided statistical evidence that the changes in spectral composition of daylight do not have a practically relevant effect on visual task performance in terms of visual acuity and color naming accuracy. However, the daylight filtered through the fully tinted glazing had a substantive impact on visual perception, evoking negative responses to the color rendering of the indoor environment and of the outside view. A mixed settings of the EC façade could improve a natural assessment of the incoming light compared to the fully tinted state, achieving better ratings in terms of perception of the indoor and outdoor environments. When given control of the EC glazing, subjects expressed higher acceptance and satisfaction compared to the tinted and mixed scenarios.

57‐2: Invited Paper: Reproducible Characterization of Automotive Full Area Local Dimming (FALD) LCDs

We research measurement conditions that allow omitting stray light blocking masks in camera‐based halo measurements of FALD LCDs. The stray light induced error is reduced by using high magnifications and stray light optimized hardware and test patterns. Our findings simplify halo measurements and enable simultaneous peak luminance and uniformity measurements.

In Vitro Digestion-In Situ Absorption Setup Employing a Physiologically Relevant Value of the Membrane Surface Area/Volume Ratio for Evaluating Performance of Lipid-Based Formulations: A Comparative Study with an In Vitro Digestion-Permeation Model.

The aim of this study is to establish and test an in vitro digestion-in situ absorption model that can mimic in vivo drug flux by employing a physiologically relevant value of the membrane surface area (S)/volume (V) ratio for accurate prediction of oral drug absorption from lipid-based formulations (LBFs). Three different types of LBFs (Type IIIA-MC, Type IIIA-LC, and Type IV) loaded with cinnarizine (CNZ), a lipophilic weak base with borderline permeability, and a control suspension were prepared. Subsequently, a simultaneous in vitro digestion-permeation experiment was conducted using a side-by-side diffusion cell with a dialysis membrane having a low S/V value. During digestion, CNZ partially precipitated for Type IV, while it remained solubilized in the aqueous phase for Type IIIA-MC and Type IIIA-LC in the donor compartment. However, in vitro drug fluxes for Type IIIA-MC and Type IIIA-LC were lower than those for Type IV due to the reduced free fraction of CNZ in the donor compartment. In pharmacokinetic studies, a similar improvement in in vivo oral exposure relative to suspension was observed, regardless of the LBFs used. Consequently, a poor correlation was found between in vitro permeation and areas under the plasma concentration-time curve (AUCoral) (R2 = 0.087). A luminal concentration measurement study revealed that this discrepancy was attributed to the extremely high absorption rate of CNZ in the gastrointestinal tract compared to that across a dialysis membrane evaluated by the in vitro digestion-permeation model, i.e., the absorption of CNZ in vivo was completed regardless of the extent of the free fraction, owing to the rapid removal of CNZ from the intestine. Subsequently, we aimed to predict the oral absorption of CNZ from the same formulations using a model that demonstrated high drug flux by employing the physiologically relevant S/V value and rat jejunum segment as an absorption sink (for replicating in vivo intestinal permeability). Predigested formulations were injected into the rat intestinal loop, and AUCloop values were calculated from the plasma concentration-time profiles. A better correlation was found between AUCloop and AUCoral (R2 = 0.72), although AUCloop underestimated AUCoral for Type IV due to the precipitation of CNZ during the predigestion process. However, this result indicated the importance of mimicking the in vivo drug absorption rate in the predictive model. The method presented herein is valuable for the development of LBFs.

Psychological and Visual Perception of Campus Lightscapes Based on Lightscape Walking Evaluation: A Case Study of Chongqing University in China

The creation of lightscapes in colleges and universities are of great significance in enhancing the perception of the campus environment, improving physical and mental health, and shaping humanistic connotations. This research aims to examine lightscape perceptions and impacts of different campuses. At Chongqing University A and B Campuses, lightscape walking experiments, subjective questionnaires, objective luminance measurements, and HDR picture processing were used to examine lightscape perception and factors. The relevance and differences in the perception of circadian lightscapes in the two campuses were analyzed using SPSS software. The study found: (1) natural lightscapes such as sky light, cloud shadow, and lake water reflection were the most popular during the daytime, while artificial lightscapes, such as decorative lighting of buildings, were positively evaluated at night; (2) the frequency of visits by a crowd directly impacts the ambiance of the environmental area; (3) males showed strong emotional awareness and social interaction skills in daytime, leading to increased social activity and stronger emotional responses, but no differences in nighttime; (4) optimal nighttime luminance enhances the overall perception satisfaction of the illumination; (5) the amount and arrangement of outdoor space, vegetation, minor landscape design, and service facilities all affect the perception of circadian lightscapes. In conclusion, design concepts and proposals of landscapes were suggested to optimize college and university lightscapes.

Development of a Competitive Chemiluminescent Assay for Quantitative Determination of TP53 Fusion Protein Using Reagent Strips.

Recent studies have shown that almost half of all cancers occur due to DNA damage. For the early diagnosis of cancer, a highly sensitized and swift identification for TP53 is needed since the corresponding TP53 protein is effectively recognized as "the guardian of the genome." To improve the detection sensitivity, numerous analytical methods were previously used for the determination of the TP53 protein, including denaturing high-performance liquid chromatography and enzyme-linked immunosorbent assay (ELISA). Currently, immunochromatographic tests (ICTs) that are simple to use, stable over time, and show low interference are regarded as valuable tools for the quick screening of food and environmental monitoring along with clinical diagnosis. ICTs often have limited sensitivity even if a variety of novel reporters possessing optimum photostability and improved brightness are used as signal-intensity reporters. Compared with N-(4-aminobutyl)-N-(ethylisoluminol) or luminol, a novel luminescent probe, 2',6'-diMethyl-4'-(N-succiniMidyloxycarbonyl) phenyl-10-sulfopropylacridiniuM-9-carboxylate (NSP-DMAE-NHS) has achieved a much higher efficiency, improvement in the biosensor's performance, and amplification of the signal without causing any damage to the biomolecule in terms of its biochemical activity. In this study, the reagent strip method was initially used to detect TP53 fusion protein by combining the advantages of NSP-DMAE-NHS and immunochromatography. In our experiment, the control and study lines on the strips were immobilized through HRP-conjugated goat anti-rabbit IgG and TP53 antigen, respectively. The optimized concentration of the anti-TP53 antibody-NSP-DMAE-NHS immunoconjugates was then added to the TP53 antigen samples. After, the test strips were inserted and left in the aforementioned buffer solution for an additional 20 min. Finally, a lab-made luminous measurement device was used to analyze the corresponding control and study lines on the strips. Under optimized conditions, this method was found to be ultrasensitive, with a wide range of linear responses from 0.0008 ng mL-1 to 1 µg mL-1 and a limit of detection of 0.0008 ng mL-1 (0.013 pM). Thus, a novel competitive chemiluminescent assay based on reagent strips was established for the determination of the TP53 fusion proteins. The strategy has potential applications for ultrasensitive detection in the early diagnosis of cancer.

Utility of Intraprocedural Luminal Diameter and Distensibility Measurements During the Esophageal Peroral Endoscopic Myotomy Procedure.

Through evaluation of the lower esophageal sphincter immediately before and after myotomy using an endoluminal functional lumen imaging probe (EFLIP), our study aimed to determine the clinical response to peroral endoscopic myotomy (POEM) and the incidence of postprocedure reflux. Achalasia is a rare esophageal motility disorder characterized by impaired relaxation of the lower esophageal sphincter (LES) and diminished peristalsis. POEM is a therapeutic option for durable management of achalasia. However, symptomatic acid reflux and esophagitis are well-known adverse effects of the procedure. Electronic medical records of 168 patients who underwent POEM for achalasia at 2 tertiary care referral centers from May 2014 to May 2021 were reviewed. EFLIP was used at a range of catheter fill volumes to assess LES dynamics. Preprocedure and postprocedure Eckardt Symptom Scores were recorded. Significant clinical improvement from POEM was sustained in over 94% of patients after 1 year. EFLIP changed intraprocedural management 5% of the time by means of myotomy extension. In patients with reflux>1 year following POEM, there was no significant difference in post-POEM LES diameter or change in LES diameter compared with those without reflux. However, post-POEM LES distensibility index (DI) was significantly higher in patients with reflux after 1 year compared with those without reflux. POEM is a safe and increasingly effective therapy for patients with symptomatic achalasia. Intraprocedural EFLIP measurements suggest that post-POEM reflux may be correlated more with DI than LES diameter. Yet, more data is needed to substantiate these outcomes.

Reducing Glare on Building Facade by Implementing Vertical Greenery Shading – user-sensation vs luminance-measurement

The user of high-rise office building usually feel discomfort glare because of high luminance from glass facade. This experimental research has an objective to find out how vertical greenery can reduce the sensation of glare. Using here a cubicle that represent one person workstation in 2m x 4m x 3.45m dimension with opening from clear glass, WWR 50%. The base case was the condition without vegetation compared to condition with Vernonia elliptica plant LAI 0.75 and LAI 1.5 which implemented as shading. The result found that vegetation LAI 1.5 can reduce luminance 54.3-56.1% compared to without vegetation. The sensation of glare from Uncomfortable becomes Perceptible (for direct light); from Perceptible-Acceptable becomes Imperceptible-Perceptible (for diffuse light). Vegetation LAI 0.75, for direct light, can reduce luminance 35.3-53.6% compared to condition without vegetation. The glare sensation vote becomes Acceptable. Whilst for diffuse light, although the luminance measurement was increase because of the reflected glare from surroundings, the natural aesthetic and green colour of leaves was relaxing, so that the sensation of glare still at the same vote, between Perceptible-Acceptable compared to without vegetation. This result proof that for biotic shading, besides the quantitative, the qualitative variables play the role.

Testing the record of climate-related cyclicity in microbial lamination: An example from Miocene oncolites in the Ebro Basin, Spain

This work tests the relationship between quasi-periodic climate-linked parameters and cyclicity recorded through microbial lamination using spectral analysis of time series based on lamina thickness and luminance, as well as C and O stable isotope data. Three oncolites of the Ebro Basin were used: specimens C4-1 and C4-31 from a lacustrine bed dated at 13.8 My, and specimen VD-13 from a fluvial bed whose age is younger than 12 My. Lamination consists of alternating light and dark calcite laminae, which correspond to crystal size and porosity variations. Composite light and dark laminae can be seen by the naked eye. Spectral analysis based on the thickness and luminance measurements of simple light–dark lamina couplet successions revealed that the three specimens had recurrent periods of 2.5, 3 and 10–13. On the hypothesis that each simple light–dark lamina couplet represents a 1-year duration, the 2.5 and 10–13 periods can be related to the 2.5-year quasi-biennial oscillation and the 11-year Schwabe sunspot cycle, respectively. Other less frequent periods present around 5 and 7, together with period 3, could be related to the most typical modes of the North Atlantic Oscillation and/or El Niño Southern Oscillation. The periods at 19–23, present in specimen C4-31, can be correlated with the 22-year Hale sunspot cycle. The 10–13 and 19–23 periods were also detected using the δ13C and δ18O values of successive laminae in specimen C4-31. These data suggest that solar irradiance variations influenced the characteristics of the oncolite laminae, through temperature and precipitation. Although the studied oncolites do not present an optimal thickness lamination pattern for spectral analysis, their lamination is capable of registering periodic climatic variations, and these results provide further evidence that microbial laminations can serve as high-resolution records of climate and climate-linked cycles over different time scales.

Laboratory Assessment of In-Pavement Airport Lamp’s Luminous Intensity Distribution

The luminous intensity measurements of airport navigational lighting should be performed in accordance with the recommendations of the European Aviation Safety Agency (EASA), which allows for the determination of the possibility of further operation or the need to replace particular lamps. This article presents a device and method for measuring the light main beam of in-pavement airport lamps used on runways and taxiways. During the measuring process in the laboratory dark room, the proposed system automatically prepares reports as heatmaps presenting angular relationships of light distribution. Photometric measurements were made using a BH1750 illuminance sensor, which was compared to a certified Sonopan L-200P luxmeter. The measurement stability of different BH1750 modes was investigated for different airport lamp power source thresholds. Due to distortions in spectral characteristic of BH1750, polynomial corrections were proposed. The functionality of the device was presented for the exemplary assessment of used and refurbished runway in-pavement airport lamps to compare their parameters change. The research results and device implementation were possible through scientific cooperation with the Poznań-Ławica Airport.

Analysis of Luminance Contrast Values at Illuminated Pedestrian Crossings in Urban Conditions

Lighting pedestrian crossings play an important role in ensuring the safety of pedestrians on the road, especially at night or in conditions of reduced visibility. Currently functioning normative and formal requirements, which are the basis for the design of lighting for pedestrian crossings, are described by criteria of lighting intensity. Each of the existing solutions operates in an urban environment, and at the stage of design and operation, the obtained values of the produced luminance contrast of the pedestrian silhouette and its background are not known. The main purpose of the article is to compare, based on luminance parameters, the three lighting solutions used at pedestrian crossings. This article presents and describes the method of determining the luminance contrast based on luminance measurements of the pedestrian silhouette and its background. Detailed results of measurements of luminance parameters at selected pedestrian crossings are presented. An analysis of the results was made with a breakdown of typical lighting solutions used in urban conditions. The differences between standard lighting were discussed, as well as supplementary and dedicated lighting. The obtained ranges of luminance contrast levels occurring in urban conditions for individual solutions were determined. The energy indicator for each solution was determined.

Energy audit on lighting system for 7-storey educational building – Energy saving opportunity

An energy audit is an important process for determining a building’s energy efficiency. This process includes verification, monitoring and analysis of energy usage and recommending ways to improve energy consumption. This paper presented a study on energy balance, utility system description, methodology to calculate the energy consumption, load apportioning and room data survey on luminance for a 7-storey educational building. The resulting data is then analysed to assess energy performance, identify opportunities for improvement without compromising safety, usability and comfort levels, and suggest potential energy savings measures that can be implemented later. As a result, it shows that the building consumed a total of 669,840.84 kWh of energy over the year of 2016 and 53.64% of the energy usage comes from lighting system. The proposed energy saving measure on lighting system for this building were expected to give 167,873.28 kWh reduction of energy per year by retrofitting an 18 watt and 36 watt of fluorescent lamp to 10 watt and 18 watt of light emitting diode lamp. The room data survey on luminance measurement also shows that 69% of the interior space is overlit, and delamping can result in a total energy savings of 45,550.08kWh per year. Lastly, the total energy saving can also contribute to 116.50 ton/year of CO2 reduction.

On-site road properties evaluation for dry and wet asphalt roads using an imaging luminance measurement device

A method was developed to investigate the reflected properties of LED and HPS-lighted wet roads using on-site measurement of luminance images. An ILMD was used to obtain high observation angles by placing it at a close distance to the ROI. The luminance images were analyzed to derive a distribution of reflected luminance as a function of deviation, incidence, and observation angles. Furthermore, an investigation of the reflected characteristics of a dry asphalt road illuminated by LED lighting was conducted, employing on-site measurements of the images of luminance and the distribution of illuminance. The results provide valuable insights for designing lighting systems and mitigating the adverse effects of glare and specular reflection on road safety.

Computed tomographic laryngotracheal dimensions in adult domestic rabbits (Oryctolagus cuniculus) are positively associated with body weight and the laryngotracheal lumen is narrowest at the level of the thyroid cartilage.

This retrospective study aimed to measure rabbit laryngotracheal dimensions at different locations on computed tomography (CT), assess the relationship of these measurements with rabbit body weight, determine the most common narrowest measurement and assess its relationship with endotracheal tube (ETT) size and body weight. 66 adult domestic rabbits (Oryctolagus cuniculus) of different breeds and body weights. CT laryngotracheal luminal height, width, and cross-sectional area measurements were made at the rostral thyroid cartilage at the level of the arytenoids, caudal thyroid cartilage/rostral cricoid cartilage, caudal cricoid cartilage/cranial trachea, and trachea at the level of the fifth cervical vertebra. The data for every measurement of luminal airway dimensions revealed robust positive associations with body weight (P < .001). The narrowest laryngotracheal measurement was the width at the level of the caudal thyroid cartilage/rostral cricoid cartilage, and the smallest cross-sectional area was at the rostral thyroid cartilage at the level of the arytenoids. There was a strong association between body weight and the likelihood of appropriate ETT fit. To have at least an 80% chance of appropriate ETT fit with a 2.0, 2.5, and 3.0 mm ETT, the rabbits' weight predicted by the model (lower 95% confidence limit) were at least 2.99 (2.72) kg, 5.24 (4.65) kg, and 5.80 (5.21) kg, respectively. The laryngotracheal lumen was narrowest at the level of the caudal thyroid cartilage in rabbits, which indicates this location may be the limiting factor in determining ETT size in rabbits.

The Influence of a Photometric Distance on Luminance Measurements

Luminance measurements are the least frequent of all photometric measurements. This article characterizes and systematizes the various methods of luminance measurement. In particular, the method of direct luminance measurement using modern luminance meters (ILMD) is described in detail. This paper presents the results of the study on the influence of the measurement distance on the luminance measurement results. Two ILMD meters (laboratory and portable) and a luminance standard were used in this study. The conducted research showed that an incorrectly chosen measuring distance can lead to significant measurement errors of up to several tens of percent. In addition, the possible impact of incorrect measurements on the design of an interior lighting installation was presented. It was shown that the selected interior lighting installation can consume more than 40 percent more electricity compared to the installation based on the correct luminance measurements of the luminaires with diffuse shades. In the final stage of the study, the definition of the photometric test distance for luminance measurements using ILMD was proposed. The test results can be particularly useful for the luminance measurements of OLEDs or the luminaires with diffuse luminous character. However, these results can also be used for luminance measurements of other light sources and luminaires.

Method for characterizing small-spot luminance in medical virtual reality headsets

We present an experimental method that utilizes a conic probe attached to an integrating sphere for characterizing the small-spot luminance of virtual reality (VR) head-mounted displays (HMDs). This allows for the measurement of relative luminance in virtual scenes and the assessment of VR displays for visualizing grayscale medical images. We characterized the relative luminance of the VIVE Pro and Oculus Rift by displaying test patterns with a circular dark spot of varying diameter in the bright field and compared the probe performance with commercially available systems. Compared to a conventional flat-panel display, the results show a significant level of veiling glare in the HMDs using both a customized conic probe with improved optical performance and an advanced imaging photometer. We also found no significant change in the relative luminance response with the probe’s working distance for the HMDs due to their unique optical architecture for near-eye viewing conditions. Our results highlight the issue of high veiling glare in HMDs and the importance of small-spot luminance measurements to adequately evaluate the technical performance of HMDs for emerging medical applications.

Characterization of Spectroradiometric Based Luminous Flux Measurements for LED Luminaires at BRIN Indonesia

Light Emitting Diode (LED) luminaires are known to have higher efficacy compared to other types of light sources. Therefore, this type of luminaire has been deployed to replace existing conventional types of light sources as means of energy-saving around the world. LED efficacy is commonly measured using a photometer mounted in a goniophotometer or an integrating sphere system. However, due to the different spectral properties of the LEDs compared with the source used in the photometer calibration, mismatch correction needs to be applied in the measurement process. Due to the arduous process of obtaining the correction, the measurement of luminous flux using a spectroradiometer is proposed in this study. By utilizing this device, the mismatch correction does not need to be applied. The measurements of several commercially available LED and energy-saving compact fluorescent luminaires (CFL) show that current LED has twice the efficacy of the CFLs. The LED shows efficacy in the range of 114 lumen/watt. The measurement uncertainty associated with the efficacy of the LED is 4.2%. It is expected that the quality assurance and the accuracy of LEDs luminaires measurement and testing in Indonesia can be improved by using the integrating sphere with the spectroradiometer measurement method.

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