Related Experiment Video
Updated: Oct 18, 2025
06:51
Dosimetry for Cell Irradiation using Orthovoltage 40-300 kV X-Ray Facilities
Published on: February 20, 2021
5.2K
Optical Attenuators Extend Dynamic Range but Alter Angular Response of Planar Ultraviolet-C Dosimeters
Alison Su1, Alisha Geldert1, Samantha M Grist2
1University of California, Berkeley - University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA.
Photochemistry and Photobiology
|October 1, 2021
Summary
Optical attenuators can extend the range of photochromic indicators (PCIs) for measuring UV-C dose on N95 respirators. However, ensuring accurate UV-C dose measurement requires careful consideration of the attenuator's angular response.
Area of Science:
- * Engineering
- * Photochemistry
- * Public Health
Background:
- * Effective decontamination of N95 respirators using ultraviolet-C (UV-C) light necessitates accurate dose measurement across the entire respirator surface.
- * Photochromic indicators (PCIs) are useful for measuring UV-C dose on complex surfaces but often saturate at lower doses than required for porous materials like N95s.
- * Extending the dynamic range of PCIs is crucial for validating UV-C decontamination protocols for N95 respirators.
Purpose of the Study:
- * To investigate the use of optical attenuators to enhance the dynamic range of PCIs for UV-C dose measurement.
- * To evaluate the impact of different attenuator types (specular vs. diffuse) on PCI angular response and UV-C measurement accuracy on N95 respirators.
- * To determine the critical role of near-ideal angular response for accurate UV-C dose quantification.
Main Methods:
- * Analytical modeling of optical attenuators to predict dynamic range extension and angular response.
- * Empirical testing of PCIs stacked behind specular (borosilicate) and diffuse (polytetrafluoroethylene) attenuators.
- * Characterization of the angular response of PCI-attenuator stacks and evaluation of on-N95 UV-C dose measurement accuracy within a decontamination system.
Main Results:
- * Both specular and diffuse attenuators increased PCI dynamic range by over 4×.
- * All tested attenuators introduced angle-dependent transmittance, leading to location-dependent underestimation of UV-C dose.
- * PCI-borosilicate and PCI-polytetrafluoroethylene stacks underreported UV-C dose by up to 40.8% and 19.8%, respectively, in steeply sloped locations.
Conclusions:
- * Optical attenuators can extend PCI dynamic range for UV-C dose measurement on N95 respirators.
- * The angular response of the attenuator is critical; non-ideal responses lead to significant measurement inaccuracies.
- * Verifying near-ideal angular response is essential for reliable UV-C dose validation in respirator decontamination.
Related Concept Videos
01:14UV–Vis Spectrometers
1.9K
The absorbance of UV and visible (UV–visible) radiations is measured using a UV–visible spectrophotometer. Deuterium lamps, which emit UV radiation, and tungsten lamps, which produce radiation in the visible region, are used as light sources in UV–visible spectrophotometers. A monochromator or prism is used for diffraction grating, i.e., to split the incoming radiation into different wavelengths. A system of slits is used to focus the desired wavelength on the sample cell.
1.9K
01:02Ultraviolet and Visible (UV–Vis) Spectroscopy: Overview
3.6K
Ultraviolet–visible (UV–visible or UV–Vis) spectroscopy is an analytical technique that investigates the interaction between matter and UV–Vis light within the electromagnetic spectrum. This method is widely used for its versatility, simplicity, and relatively quick data acquisition, making it valuable for both qualitative and quantitative analysis. When UV–Vis radiation passes through a material, molecules absorb light depending on the energy required for...
3.6K