Spectroradiometric detector measurements :

Larason, Thomas C.; Houston, Jeanne M.

doi:10.6028/nist.sp.250-41e2008

Cited by 34 publications

(28 citation statements)

References 75 publications

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“…The light exiting the polarization rotation optics was analyzed with a linear polarizer, set to a random angle in front of a calibrated Si photodetector placed in front of the objective lens. 19 The wave plates were fine-adjusted so that there was a maximum between extinction, where the polarization of the light is perpendicular to the polarizer, and the signal when the polarization of the light is aligned with the analyzing polarizer. Several analyzer angles were checked to ensure proper alignment of the polarization rotator.…”

Section: A Polarization Rotatormentioning

confidence: 99%

Quantitative scheme for full-field polarization rotating fluorescence microscopy using a liquid crystal variable retarder

Lesoine

Lee

Krogmeier

et al. 2012

Review of Scientific Instruments

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We present a quantitative scheme for full-field polarization rotating fluorescence microscopy. A quarter-wave plate, in combination with a liquid crystal variable retarder, provides a tunable method to rotate polarization states of light prior to its being coupled into a fluorescence microscope. A calibration of the polarization properties of the incident light is performed in order to correct for elliptical polarization states. This calibration allows the response of the sample to linear polarization states of light to be recovered. Three known polarization states of light can be used to determine the average fluorescent dipole orientations in the presence of a spatially varying dc offset or background polarization-invariant fluorescence signal. To demonstrate the capabilities of this device, we measured a series of full-field fluorescence polarization images from fluorescent analogs incorporated in the lipid membrane of Burkitts lymphoma CA46 cells. The fluorescent lipid-like analogs used in this study are molecules that are labeled by either a DiI (1,1(')-Dioctadecyl 3,3,3('),3(')-Tetramethylindocarbocyanine) fluorophore in its head group or a Bodipy (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) molecule in its acyl chain. A spatially varying contrast in the normalized amplitude was observed on the cell surface, where the orientation of the DiI molecules is tangential to the cell membrane. The internally labeled cellular structures showed zero response to changes in linear polarization, and the net linear polarization amplitude for these regions was zero. This instrument provides a low cost calibrated method that may be coupled to existing fluorescence microscopes to perform investigations of cellular processes that involve a change in molecular orientations.

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Section: A Polarization Rotatormentioning

confidence: 99%

Quantitative scheme for full-field polarization rotating fluorescence microscopy using a liquid crystal variable retarder

Lesoine

Lee

Krogmeier

et al. 2012

Review of Scientific Instruments

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“…The tie points have been derived recently from a Si-trap detector and earlier from a single element Ge photodiode, both traceable to the NIST reference responsivity scale [9]. During the calibration of the first two working standard radiometers, more tie points have been derived from an earlier developed LiNbO 3 pyroelectric radiometer standard [5] and also from a single element LiTaO 3 pyroelectric transfer detector (PD2) calibrated against the primary standard cryogenic radiometer at 10.6 µm [10].…”

Section: Calibration Of Pyroelectric Radiometersmentioning

confidence: 99%

Development and calibration of pyroelectric radiometer standards at NIST

Eppeldauer

Zeng

Hanssen

2006

Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense V

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The reference spectral power responsivity scale of NIST is being extended from the silicon range to the infrared (IR) using pyroelectric radiometers. Two transfer standard pyroelectric radiometers have been developed at NIST. The main design consideration was to obtain only a minimal increase in the measurement uncertainty during the responsivity scale extension. Domain engineered LiNbO 3 and regular LiTaO 3 pyroelectric detectors were used in the two radiometers. Both detectors are gold-black coated and temperature controlled. Reflecting domes are attached to the radiometer inputs to decrease the reflectance loss and to improve the spatial uniformity of responsivity in the infrared. Four commercial pyroelectric detectors have been added to the group and used as working standards. The relative spectral responsivity of all pyroelectric detectors was determined from spectral reflectance measurements. The radiant power responsivity tie points were derived from Si trap and single element detectors traceable to the NIST reference responsivity scale. The pyroelectric radiometers have been characterized for frequency and temperature dependent responsivity, noise, spatial non-uniformity of responsivity, angular responsivity, and linearity. The expanded (relative) uncertainty of the spectral power responsivity calibrations ranged between 0.5 % and 1.2 % (k=2) within the 1 µm to 19 µm range.

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“…In the visible, the metrology standards are generally silicon photodiodes, whose calibration can be traced back to the Primary Optical Watt Radiometer (POWR, Houston & Rice 2006), an electrical cryogenic substitution radiometer maintained by the National Institute of Standards and Technology (NIST) as the official implementation of the optical watt. To characterise the photodiodes provided to its end users, NIST maintains a sophisticated metrology chain (Larason & Houston 2008) involving intermediate light sources, notably the SIRCUS laser facility (Brown et al 2006 and the Spectral Comparator Facility (SCF). With a calibrated photodiode in hand and the goal of calibrating another light detector, the end user has no choice but to build an intermediate light source to transfer the NIST flux scale to his own instrument.…”

Section: Introductionmentioning

confidence: 99%

“…For this reason, nearly every modern survey has plans to build and operate a dedicated calibration source, able to follow the shape and normalisation of the imager passbands in real time. A precursor in this domain POWR (NIST) (Houston & Rice, 2006) SIRCUS/SCF (NIST) (Brown et al, 2006 (Larason & Houston, 2008 . Generic metrology chain from POWR, the official implementation of the optical watt, which is maintained at NIST, to the telescope imagers.…”

Section: Introductionmentioning

confidence: 99%

The DICE calibration project Design, characterization, and first results

Regnault

Guyonnet

Schahmanèche

et al. 2015

A&A

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Aims. We describe the design, operation, and first results of a photometric calibration project, called DICE (Direct Illumination Calibration Experiment), aiming at achieving precise instrumental calibration of optical telescopes. The heart of DICE is an illumination device composed of 24 narrow-spectrum, high-intensity, light-emitting diodes (LED) chosen to cover the ultraviolet-to-nearinfrared spectral range. It implements a point-like source placed at a finite distance from the telescope entrance pupil, yielding a flat field illumination that covers the entire field of view of the imager. The purpose of this system is to perform a lightweight routine monitoring of the imager passbands with a precision better than 5 per-mil on the relative passband normalisations and about 3 Å on the filter cutoff positions. Methods. Prior to installation, the light source is calibrated on a spectrophotometric bench. As our fundamental metrology standard, we use a photodiode calibrated at the National Institute of Standards and Technology (NIST). The radiant intensity of each beam is mapped, and spectra are measured for each LED. All measurements are conducted at temperatures ranging from 0• C to 25• C in order to study the temperature dependence of the system. The photometric and spectroscopic measurements are combined into a model that predicts the spectral intensity of the source as a function of temperature. Results. We find that the calibration beams are stable at the 10 −4 level -after taking the slight temperature dependence of the LED emission properties into account. We show that the spectral intensity of the source can be characterised with a precision of 3 Å in wavelength, depending on how accurately we are able to calibrate the wavelength response of the mononochromator. In flux, we reach an accuracy of about 0.2−0.5% depending on how we understand the off-diagonal terms of the error budget affecting the calibration of the NIST photodiode. We describe how with a routine < ∼ 60-mn calibration program, the apparatus is able to constrain the imager passbands at the targeted precision levels.

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Spectroradiometric detector measurements :

Cited by 34 publications

References 75 publications

Quantitative scheme for full-field polarization rotating fluorescence microscopy using a liquid crystal variable retarder

Quantitative scheme for full-field polarization rotating fluorescence microscopy using a liquid crystal variable retarder

Development and calibration of pyroelectric radiometer standards at NIST

The DICE calibration project Design, characterization, and first results

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