Ultraviolet Germicidal Irradiation (UVGI) is a proven method of disinfection for both bacterial and viral pathogens. Since the acceleration of the COVID-19 pandemic caused by SARS-CoV-2, the industry has witnessed significant technological innovation and an influx of UV-C LEDs, devices, and disinfectant enclosures. To ensure germicidal efficacy, UV-C LEDs and associated devices need accurate characterization of their optical power and irradiance. When UV-C sources are installed in enclosures and rooms, additional challenges arise that need to be evaluated to ensure germicidal efficacy is maintained. These challenges include 1) under- and over-dosing due to non-uniformity of UV-C dosage, 2) poorly understood room/chamber dynamics and reflectance, 3) shadowing, and 4) sensor, material, and source degradation. Here, we introduce a new detector portfolio that is calibrated at critical UV-C wavelengths, such as 265 nm, and enables real time UV-C Irradiance measurements at near-field and far-field. Temporal monitoring of irradiance allows for real time dosage calculation. Seasoned optical components ensure accurate detector performance and enable source output degradation monitoring. An adaptable API, network capability, and a dashboard facilitate simultaneous monitoring of multiple detectors and easy integration with existing installation infrastructure. With a proprietary cosine diffuser, these detectors include an exceptional f2 directional response making them ideal for deployment in rooms, enclosures, and HVAC systems.
Building on our experience with solid-state tunable light sources, Labsphere has developed an ultra-tunable spectral radiance calibration sources that uses a continuous-spectrum light source and polychromator technology to offer incomparable control of generated spectral waveforms. These Sources can reproduce complex spectral features with a precision that enables high-resolution simulation of standard illuminants as well as natural or synthetic sources and emissions. These sources provide uniform flat field radiance of optical sensors characterization and can be adapted with optical light guides and collimators for directional spectral illumination. During this demonstration we will walk you through examples of how easy it is to upload a spectrum from a data file and reproduce it using the UT-1000. We even make it easier with an accessory that allows one to measure light from an illumination source or reflected light off a surface and reproduce it with UT-1000. The measured spectrum is fed into the UT-1000 which reproduces the measured spectrum in a highly uniform spectral radiance almost instantaneously. A reference light source that can produce any imaginable visible spectrum... Imagine the possibilities!
Sintered PTFE is an extremely stable, near-perfect Lambertian reflecting diffuser and calibration standard material that has been used by national labs, space, aerospace and commercial sectors for over two decades. New uncertainty targets of 2% on-orbit absolute validation in the Earth Observing Systems community have challenged the industry to improve is characterization and knowledge of almost every aspect of radiometric performance (space and ground). Assuming “near perfect” reflectance for angular dependent measurements is no longer going to suffice for many program needs. The total hemispherical spectral reflectance provides a good mark of general performance; but, without the angular characterization of bidirectional reflectance distribution function (BRDF) measurements, critical data is missing from many applications and uncertainty budgets. Therefore, traceable BRDF measurement capability is needed to characterize sintered PTFE’s angular response and provide a full uncertainty profile to users. This paper presents preliminary comparison measurements of the BRDF of sintered PTFE from several laboratories to better quantify the BRDF of sintered PTFE, assess the BRDF measurement comparability between laboratories, and improve estimates of measurement uncertainties under laboratory conditions.
Integrating sphere (IS) based uniform sources are a primary tool for ground based calibration, characterization and testing of flight radiometric equipment. The idea of a Lambertian field of energy is a very useful tool in radiometric testing, but this concept is being checked in many ways by newly lowered uncertainty goals. At an uncertainty goal of 2% one needs to assess carefully uniformity in addition to calibration uncertainties, as even sources with a 0.5% uniformity are now substantial proportions of uncertainty budgets. The paper explores integrating sphere design options for achieving 99.5% and better uniformity of exit port radiance and spectral irradiance created by an integrating sphere. Uniformity in broad spectrum and spectral bands are explored. We discuss mapping techniques and results as a function of observed uniformity as well as laboratory testing results customized to match with customer’s instrumentation field of view. We will also discuss recommendations with basic commercial instrumentation, we have used to validate, inspect, and improve correlation of uniformity measurements with the intended application.
An essential part of characterizing and improving imaging system performance and modeling is the determination of spectral responsivity; namely the spectral band-shape and out-of-band response. These complicated measurements have heretofore been difficult to make with consistency with do-it-yourself solutions. To address this industry-wide problem, Labsphere has developed an automated spectral response measurement stations, incorporating several techniques to enhance accuracy and ease of use. This presentation will cover the physics and considerations behind the scaling of these types of systems and the experimental methodology required to assure absolute traceability, as well as some of the lessons learned along the way.
Integrating spheres for optical calibration of remote sensing cameras have traditionally been made with Quartz
Tungsten Halogen (QTH) lamps because of their stability. However, QTH lamps have the spectrum of a blackbody
at approximately 3000K, while remote sensing cameras are designed to view a sun-illuminated scene. This presents
a severe significant mismatch in the blue end of the spectrum. Attempts to compensate for this spectral mismatch
have primarily used Xenon lamps to augment the QTH lamps. However, Xenon lamps suffer from temporal
instability that is not desirable in many applications. This paper investigates the possibility of using RF-excited
plasma lamps to augment QTH lamps. These plasma lamps have a somewhat smoother spectrum than Xenon. Like
Xenon, they have more fluctuation than QTH lamps, but the fluctuations are slower and may be able to be tracked in
an actual OGSE light source. The paper presents measurements of spectra and stability. The spectrum is measured
from 320 nm to 2500 nm and the temporal stability from DC to 10 MHz. The RF-excited plasma lamps are quite
small, less than 10mm in diameter and about 15 mm in length. This makes them suitable for designing reasonably
sized reflective optics for directing their light into a small port on an integrating sphere. The concludes with a
roadmap for further testing.
Application-specific integrating sphere-based, integral veiling glare measurement systems are described. The sources use
the integral method for measuring the veiling glare (VG) index of various lens-based imaging systems. The calibration
source has provisions in the form of a collimating lens holder to simulate a situation where the black target and bright
surround are at a sufficiently great distance to give measurements of VG index which are the same as that which would
result if the distance where infinite. The design criteria for the integral VG test source are presented. Included is a
summary of the end-user specifications in regards to spectral radiance, levels of attenuation, irradiance stability, and
aperture uniformity and contrast. Spectral radiometric predictions and actual output levels are compared.
An application-specific contracted integrating sphere source of uniform spectral radiance is described. The source is used
for pre-launch test and calibration of imaging radiometers which will be used as satellite borne earth remote sensors.
The calibration source is primarily intended to serve as a transfer standard of radiance.
Design criteria for the uniform radiance source are presented. Included is a summary of the end-user specifications in
regards to spectral radiance, radiance levels of attenuation, radiance stability, and aperture uniformity. Radiometric
theory used to predict the source radiance for a specific spectral flux input is reviewed. Reasoning for the use of an
integrating sphere platform for this application and characteristic features of the source are discussed.
Calibration methods and instrumentation are described. The resultant data presented include the modeled data compared
with the measured performance. Methods of data reduction and uncertainty are addressed where applicable.
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