Equipment developed for simplifying routine phototesting in dermatology

Some people react abnormally when exposed to sunlight by getting easily burned or develop a rash. When testing a patient's level of photosensitivity in the clinic, the UVR dose to provoke erythema is determined by the minimal erythema dose (MED) test. Subsequently, a photoprovocation test is performed to detect abnormal skin reactions by daily exposing the skin to UVR for several consecutive days. Associated problems in MED testing include choice of an even skin area for testing, patients keeping still during the test, testing with different UVR doses simultaneously, and securing clear borders of erythema. To address these issues, a MED Test Patch was developed which adheres closely to the skin to ensure sharp erythema borders and provides six irradiation fields with decremental doses of 20%. For MED testing, we constructed a solar simulator and LED lamps with peak emissions at 309 and 370 nm, small enough to be mounted directly on to the MED Test Patch and accommodate patient movements. These lamps and a 415 nm LED can also be used for provocation testing which is best performed on the back where the skin is assumed to have identical UVR sensitivity, and the area is large enough for adjacent MED and provocation test fields. Reading of erythema is still performed by visual and tactile evaluation. The UVA and UVB MED test can be performed in 1 h. The advantage of these developments is an easy-to-use, standardized test method with improved accuracy of the results.

Predictive analysis of the power spectral irradiance from blackbody radiation source using single pixel detector

Accurate spectral irradiance measurement in the near-infrared range is significant for the design and characterization of photodetector and photovoltaic cells. Approximation method is commonly used to solve for the input power using estimated spectral irradiance, where the dependency on wavelength and temperature remains uncertain. This study aims to determine the power spectrum at different radiation temperatures using a single pixel photodetector, taking into consideration factors such as transmission spectra of alumina radiator, CaF2 collimating lens, responsivity, and measured photocurrent information of photodetectors. Utilizing predictive mathematical model, five commercial photodetectors, including Silicon, Germanium, In0.53Ga0.47As, In0.73Ga0.27As, and In0.83Ga0.17As were used to solve for the power densities as a function of wavelengths at radiation temperatures of 1000 °C and 1500 °C. The spectral irradiance of photodetectors was determined with a percentage difference of <4.9 %, presenting an accurate power density estimation for the spectrum at a wide range of radiation temperatures. Power irradiance data obtained were validated in the narrow wavelength range with 1000 nm, 1400 nm, 1500 nm, and 2000 nm bandpass filters. The reported work demonstrates a simple and efficient way which could contribute to develop a cost-effective method of measuring and determining the spectrum irradiances of objects at different radiation temperatures. This predictive analysis method hopefully intensifies the progress of efforts to reduce the reliance on complex optoelectronic instruments in accurately solving power irradiance information.

Spectral comparison of diffuse PAR irradiance under different tree and shrub shading conditions and in cloudy days

Spectral Solar Photosynthetically Photon Flux Density (PPFD) (380 to 780 nm) reaching the surface of a plant in different lighting conditions has been analyzed in order to better understand the different photosynthetic performance of plants depending on their spatial situation and the vegetation surrounding. A comparison between the shadow of several trees in a sunny day and the case of a cloudy day in an open space has been studied. Three isolated trees (a palm tree, an olive tree and a shrub oleander) and a tipuana grove have been studied. The study has been developed in Valencia (Spain) during January and February 2017. A portable Asensetek Standard ALP-01 spectrometer with a measurement wavelength range of 380 to 780 nm, has been used. Conditions with higher PPFD received are found to be, apart from those of a sunny day, those for cloudy day (with a spectral maximum in the Green region of the spectrum), and those for individual trees and shrub shadows in a sunny day (with a spectral maximum in the Blue region). The case in which less amount of PPFD is received is that under the shadow of tipuana grove (with a spectral maximum in the Infrared region of the spectrum). In fact the order of magnitude in which the PPFD in a cloudy day exceeds the PPFD under the tipuana grove shade is up to 20.