Photometry and Radiometry

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Photometry and radiometry Measurement of luminous and solar characteristics according to EN 410 Measurement of the spectral transmission () and reflection () in the wavelength range between 250 nm and 2500 nm at small samples 40 x 70 mm of single panes in the UV-VIS-NIR- spectrometer Typical spectral transmittance The spectrum of the sun 100 UV Sichtbar Infrarot 90 5% 50% 45% 80 100 ideale selektive Transmission 70 80 60 50 Float glass 60 Thermal protection layer Sonnenspektrum 40 Solar control layer 2 40 I = 1kW/m 30 20 20 % in Transmissionsgrad 10 relative spektrale Intensität in % 0 0 200 600 1000 1400 1800 2200 0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 Visible area 380-780 nm Wavelength Wellenlänge in nm 100 % Solar energy q = 16 % The following values can be measured and/or calculated for glasses i The luminous values of qa = 12 % insulating glass units are g total solar energy transmittance (g==e+qi) v light transmittance determined calculative on basis of the measured solar transmittance light reflectance e v single panes. e solar reflectance UV UV-transmittance = 26 % e = 46 % qi secundary heat flow Total solar energy transmittance g = 62% Measurement of light transmission v and light reflexion v for light diffusing and light channelling products according to DIN 5036 and/or EN 14500 Light diffusing products are e.g. screen-printed glass, etched Picture of the integrating sphere at ift Rosenheim glass, glass with integrated installation and solar control products like fabrics and lamella. For systems that have angle depending characteristics, the radiation angle can vary from 0°to 60° Measurement principle of the integrating sphere 1 Sample 2 Light D65 Measurement of emissivity n according to EN 12898 Example for the influence of lowE-coating on the Ug-value Every body radiates heat. The emissivity of a body indicates how much radiation it gives compared with an ideal radiant Air Air Argon warmers, a black body. Radiation Conduction The emissivity n of the surfaces has among other things influence on the Ug-value of the insulating glass unit; the lower Convection IR- the emissivity, the lower the Ug-value. reflective coating Typical values for nare: Standard float glass 0.89 a i a i a i Solar control coating 0.02 Thermal insulation coating 0.03 - 0.06 Ug = 3.0 W/(m2.K) Ug = 1.5 W/(m2.K) Ug = 1.2 W/(m2.K) ift Rosenheim GmbH, Theodor-Gietl-Str. 7-9, 83026 Rosenheim, Tel. +49 (80 31) 261-0, Fax: +49 (80 31) 261-290, E-Mail [email protected], www.ift-rosenheim.de .

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CIE Technical Note 004:2016
TECHNICAL NOTE The Use of Terms and Units in Photometry – Implementation of the CIE System for Mesopic Photometry CIE TN 004:2016 CIE TN 004:2016 CIE Technical Notes (TN) are short technical papers summarizing information of fundamental importance to CIE Members and other stakeholders, which either have been prepared by a TC, in which case they will usually form only a part of the outputs from that TC, or through the auspices of a Reportership established for the purpose in response to a need identified by a Division or Divisions. This Technical Note has been prepared by CIE Technical Committee 2-65 of Division 2 “Physical Measurement of Light and Radiation" and has been approved by the Board of Administration as well as by Division 2 of the Commission Internationale de l'Eclairage. The document reports on current knowledge and experience within the specific field of light and lighting described, and is intended to be used by the CIE membership and other interested parties. It should be noted, however, that the status of this document is advisory and not mandatory. Any mention of organizations or products does not imply endorsement by the CIE. Whilst every care has been taken in the compilation of any lists, up to the time of going to press, these may not be comprehensive. CIE 2016 - All rights reserved II CIE, All rights reserved CIE TN 004:2016 The following members of TC 2-65 “Photometric measurements in the mesopic range“ took part in the preparation of this Technical Note. The committee comes under Division 2 “Physical measurement of light and radiation”.
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Fundametals of Rendering - Radiometry / Photometry
Fundametals of Rendering - Radiometry / Photometry “Physically Based Rendering” by Pharr & Humphreys •Chapter 5: Color and Radiometry •Chapter 6: Camera Models - we won’t cover this in class 782 Realistic Rendering • Determination of Intensity • Mechanisms – Emittance (+) – Absorption (-) – Scattering (+) (single vs. multiple) • Cameras or retinas record quantity of light 782 Pertinent Questions • Nature of light and how it is: – Measured – Characterized / recorded • (local) reflection of light • (global) spatial distribution of light 782 Electromagnetic spectrum 782 Spectral Power Distributions e.g., Fluorescent Lamps 782 Tristimulus Theory of Color Metamers: SPDs that appear the same visually Color matching functions of standard human observer International Commision on Illumination, or CIE, of 1931 “These color matching functions are the amounts of three standard monochromatic primaries needed to match the monochromatic test primary at the wavelength shown on the horizontal scale.” from Wikipedia “CIE 1931 Color Space” 782 Optics Three views •Geometrical or ray – Traditional graphics – Reflection, refraction – Optical system design •Physical or wave – Dispersion, interference – Interaction of objects of size comparable to wavelength •Quantum or photon optics – Interaction of light with atoms and molecules 782 What Is Light ? • Light - particle model (Newton) – Light travels in straight lines – Light can travel through a vacuum (waves need a medium to travel in) – Quantum amount of energy • Light – wave model (Huygens): electromagnetic radiation: sinusiodal wave formed coupled electric (E) and magnetic (H) fields 782 Nature of Light • Wave-particle duality – Light has some wave properties: frequency, phase, orientation – Light has some quantum particle properties: quantum packets (photons). • Dimensions of light – Amplitude or Intensity – Frequency – Phase – Polarization 782 Nature of Light • Coherence - Refers to frequencies of waves • Laser light waves have uniform frequency • Natural light is incoherent- waves are multiple frequencies, and random in phase.
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Variable Star Photometry with a DSLR Camera
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Chapter 4 Introduction to Stellar Photometry
Chapter 4 Introduction to stellar photometry Goal-of-the-Day Understand the concept of stellar photometry and how it can be measured from astro- nomical observations. 4.1 Essential preparation Exercise 4.1 (a) Have a look at www.astro.keele.ac.uk/astrolab/results/week03/week03.pdf. 4.2 Fluxes and magnitudes Photometry is a technique in astronomy concerned with measuring the brightness of an astronomical object’s electromagnetic radiation. This brightness of a star is given by the flux F : the photon energy which passes through a unit of area within a unit of time. The flux density, Fν or Fλ, is the flux per unit of frequency or per unit of wavelength, respectively: these are related to each other by: Fνdν = Fλdλ (4.1) | | | | Whilst the total light output from a star — the bolometric luminosity — is linked to the flux, measurements of a star’s brightness are usually obtained within a limited frequency or wavelength range (the photometric band) and are therefore more directly linked to the flux density. Because the measured flux densities of stars are often weak, especially at infrared and radio wavelengths where the photons are not very energetic, the flux density is sometimes expressed in Jansky, where 1 Jy = 10−26 W m−2 Hz−1. However, it is still very common to express the brightness of a star by the ancient clas- sification of magnitude. Around 120 BC, the Greek astronomer Hipparcos ordered stars in six classes, depending on the moment at which these stars became first visible during evening twilight: the brightest stars were of the first class, and the faintest stars were of the sixth class.
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Basics of Photometry Photometry: Basic Questions
Basics of Photometry Photometry: Basic Questions • How do you identify objects in your image? • How do you measure the flux from an object? • What are the potential challenges? • Does it matter what type of object you’re studying? Topics 1. General Considerations 2. Stellar Photometry 3. Galaxy Photometry I: General Considerations 1. Garbage in, garbage out... 2. Object Detection 3. Centroiding 4. Measuring Flux 5. Background Flux 6. Computing the noise and correlated pixel statistics I: General Considerations • Object Detection How do you mathematically define where there’s an object? I: General Considerations • Object Detection – Define a detection threshold and detection area. An object is only detected if it has N pixels above the threshold level. – One simple example of a detection algorithm: • Generate a segmentation image that includes only pixels above the threshold. • Identify each group of contiguous pixels, and call it an object if there are more than N contiguous pixels I: General Considerations • Object Detection I: General Considerations • Object Detection Measuring Flux in an Image • How do you measure the flux from an object? • Within what area do you measure the flux? The best approach depends on whether you are looking at resolved or unresolved sources. Background (Sky) Flux • Background – The total flux that you measure (F) is the sum of the flux from the object (I) and the sky (S). F = I + S = #Iij + npix " sky / pixel – Must accurately determine the level of the background to obtaining meaningful photometry ! (We’ll return to this a bit later.) Photometric Errors Issues impacting the photometric uncertainties: • Poisson Error – Recall that the statistical uncertainty is Poisson in electrons rather than ADU.
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An Introduction to Photometry and Photometric Measurements Henry
An introduction to photometry and photometric measurements Henry Joy McCracken Institut d’Astrophysique de Paris What is photometry? • Photometry is concerned with obtaining quantitative physical measurements of astrophysical objects using electromagnetic radiation. • The challenge is to relate instrumental measurements (like electrons counted in an electronic detector) to physically meaningful quantities like ﬂux and ﬂux density • The ability to make quantitative measurements transformed astronomy from a purely descriptive science to one with great explanative power. To print higher-resolution math symbols, click the Hi-Res Fonts for Printing button on the jsMath control panel. Brightness and Flux Density Astronomers learn about an astronomical source by measuring the strength of its radiation as a function of direction on the sky (by mapping or imaging) and frequency (spectroscopy), plus other quantities (time, polarization) that we ignore for now. We need precise and quantitative definitions to describe the strength of radiation and how it varies with distance between the source and the observer. The concepts of brightness and flux density are deceptively simple, but they regularly trip up experienced astronomers. It is very important to understand them clearly because they are so fundamental. We start with the simplest possible case of radiation traveling from a source through empty space (so there is no absorption, scattering, or emission along the way) to an observer. In the ray-optics approximation, radiated energy flows in straight lines. This approximation is valid only for systems much larger than the wavelength of the radiation, a criterion easily met by astronomical sources. You may find it helpful to visualize electromagnetic radiation as a stream of light particles (photons), essentially bullets that travel in straight lines at the speed of light.
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41 Photometry Standardization Measurement with Integrating Spheres Standards for Smart Lighting Voltage Limits for PWM Operated
www.led-professional.com ISSN 1993-890X Review LpR The leading worldwide authority for LED & OLED lighting technology information Jan/Feb 2014 | Issue 41 Photometry Standardization Measurement with Integrating Spheres Standards for Smart Lighting Voltage Limits for PWM Operated LED Drivers EDITORIAL 1 Safety & Quality Experience shows that early adoption of many new technology developments into the market goes hand in hand with a lack of quality, and in some cases, a critical lack of safety. There are several reasons for this: One is the balancing of test time and test conditions against proven data before entering the market. Another reason is that every new technology and/or technical system displays “unexpected” or “unknown” behaviors under certain conditions. Third of all, international standards are lagging behind the rapidly changing technologies. Standardization bodies need input and experiences as well as concrete problems in order to be able to adapt and/or expand their standards. Everyone seems to be confronted with a more or less “insecure” situation where quality and safety issues may arise and possibly target LED technology in general. When looking at lighting systems or luminaires, all components and modules are important and somehow related to safety and quality. In addition to that, the combination and integration of different parts can have unforeseen effects. There is an article in this issue of LED professional Review which covers one aspect of this: How specific conditions in real applications may lead to critical operation behaviors in regards to safety in the PWM mode of LED drivers. The electronic circuit design can be seen as a very relevant topic for guaranteeing the necessary quality and safety levels.
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Radiometry and Photometry
Radiometry and Photometry Wei-Chih Wang Department of Power Mechanical Engineering National TsingHua University W. Wang Materials Covered • Radiometry - Radiant Flux - Radiant Intensity - Irradiance - Radiance • Photometry - luminous Flux - luminous Intensity - Illuminance - luminance Conversion from radiometric and photometric W. Wang Radiometry Radiometry is the detection and measurement of light waves in the optical portion of the electromagnetic spectrum which is further divided into ultraviolet, visible, and infrared light. Example of a typical radiometer 3 W. Wang Photometry All light measurement is considered radiometry with photometry being a special subset of radiometry weighted for a typical human eye response. Example of a typical photometer 4 W. Wang Human Eyes Figure shows a schematic illustration of the human eye (Encyclopedia Britannica, 1994). The inside of the eyeball is clad by the retina, which is the light-sensitive part of the eye. The illustration also shows the fovea, a cone-rich central region of the retina which affords the high acuteness of central vision. Figure also shows the cell structure of the retina including the light-sensitive rod cells and cone cells. Also shown are the ganglion cells and nerve fibers that transmit the visual information to the brain. Rod cells are more abundant and more light sensitive than cone cells. Rods are 5 sensitive over the entire visible spectrum. W. Wang There are three types of cone cells, namely cone cells sensitive in the red, green, and blue spectral range. The approximate spectral sensitivity functions of the rods and three types or cones are shown in the figure above 6 W. Wang Eye sensitivity function The conversion between radiometric and photometric units is provided by the luminous efficiency function or eye sensitivity function, V(λ).
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Basic Principles of Imaging and Photometry Lecture #2
Basic Principles of Imaging and Photometry Lecture #2 Thanks to Shree Nayar, Ravi Ramamoorthi, Pat Hanrahan Computer Vision: Building Machines that See Lighting Camera Physical Models Computer Scene Scene Interpretation We need to understand the Geometric and Radiometric relations between the scene and its image. A Brief History of Images 1558 Camera Obscura, Gemma Frisius, 1558 A Brief History of Images 1558 1568 Lens Based Camera Obscura, 1568 A Brief History of Images 1558 1568 1837 Still Life, Louis Jaques Mande Daguerre, 1837 A Brief History of Images 1558 1568 1837 Silicon Image Detector, 1970 1970 A Brief History of Images 1558 1568 1837 Digital Cameras 1970 1995 Geometric Optics and Image Formation TOPICS TO BE COVERED : 1) Pinhole and Perspective Projection 2) Image Formation using Lenses 3) Lens related issues Pinhole and the Perspective Projection Is an image being formed (x,y) on the screen? YES! But, not a “clear” one. screen scene image plane r =(x, y, z) y optical effective focal length, f’ z axis pinhole x r'=(x', y', f ') r' r x' x y' y = = = f ' z f ' z f ' z Magnification A(x, y, z) B y d B(x +δx, y +δy, z) optical f’ z A axis Pinhole A’ d’ x planar scene image plane B’ A'(x', y', f ') B'(x'+δx', y'+δy', f ') From perspective projection: Magnification: x' x y' y d' (δx')2 + (δy')2 f ' = = m = = = f ' z f ' z d (δx)2 + (δy)2 z x'+δx' x +δx y'+δy' y +δy = = Area f ' z f ' z image = m2 Areascene Orthographic Projection Magnification: x' = m x y' = m y When m = 1, we have orthographic projection r =(x, y, z) r'=(x', y', f ') y optical z axis x z ∆ image plane z This is possible only when z >> ∆z In other words, the range of scene depths is assumed to be much smaller than the average scene depth.
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A Luminous Efficiency Function, V*(1), for Daylight Adaptation
Journal of Vision (2005) 5, 948–968 http://journalofvision.org/5/11/3/ 948 A luminous efficiency function, V *(1), for daylight adaptation Institute of Ophthalmology, University College London, Lindsay T. Sharpe London, United Kingdom Institute of Ophthalmology, University College London, Andrew Stockman London, United Kingdom Forschungstelle fu¨r Experimentelle Ophthalmologie, Wolfgang Jagla Universita¨ts-Augenklinik, Tu¨bingen, Germany Forschungstelle fu¨r Experimentelle Ophthalmologie, Herbert Ja¨gle Universita¨ts-Augenklinik, Tu¨bingen, Germany We propose a new luminosity function, V Ãð1Þ, that improves upon the original CIE 1924 Vð1Þ function and its modification by D. B. Judd (1951) and J. J. Vos (1978), while being consistent with a linear combination of the A. Stockman & L. T. Sharpe (2000) long-wavelength-sensitive (L) and middle-wavelength-sensitive (M) cone fundamentals. It is based on experimentally determined 25 Hz, 2- diameter, heterochromatic (minimum) flicker photometric data obtained from 40 observers (35 males, 5 females) of known genotype, 22 with the serine variant L(ser180), 16 with the alanine L(ala180) variant, and 2 with both variants of the L-cone photopigment. The matches, from 425 to 675 nm in 5-nm steps, were made on a 3 log troland xenon white (correlated color temperature of 5586 K but tritanopically metameric with CIE D65 standard daylight for the Stockman and Sharpe L- and M-cone fundamentals in quantal units) adapting field of 16- angular subtense, relative to a 560-nm standard. Both the reference standard and test lights were kept near flicker threshold so that, in the region of the targets, the total retinal illuminance averaged 3.19 log trolands.
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Galaxy Photometry
Galaxy Photometry For galaxies, we measure a surface flux, that is, the counts in each pixel. Through calibration, this is converted to flux density in Janskys (1 Jy = -26 2 10 W/m /Hz). 1 For a galaxy at some distance, d, a pixel of side D subtends an angle, α, given by r d D α D α= . d The surface brightness is the amount of light in that patch of sky divided by its area (in arsec2): Flux Jy I(r)= . α22arcsec Luminosity Recalling the relationship between flux and luminosity, Flux = , the surface π 2 brightness becomes 4d 2 F L d L L Watts = = = I(r) 22 2 2 or 2. απ4 dD 4 π D pc arcsec Which is often given in solar luminosities per parsec2. To convert this to magnitudes, recall that the apparent magnitude is a measure of flux, F m−=− m 2.5 log . 0 F 0 So the surface brightness in magnitudes per arsec2 is F α2 µ−µ =−2.5 log , 0 α2 F0 I µ−µ =−2.5 log. 0 I 0 2 EXAMPLE: For the Sun in the optical V-Band, taking I0 = 1 L/pc 2 for µ0 = 26.4 magnitudes/arcsec , yields µ=−2.5 log( I) + 26.4 mag/arcsec2 . Giving the surface brightness (in the V-band in this case), as 0.4( 26.4−µ ) L = V V IV 10 . pc2 1 From Amina Helmi’s Kapteyn course at www.astro.rug.nl/~ahelmi/teaching/gal2010/ellipt.pdf Galaxy Photometry Undergraduate ALFALFA Team AOD 6/28/2016 The total (apparent) magnitude of the galaxy is the surface brightness integrated over the entire galaxy.
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Radiometry and Photometry
Radiometry and Photometry Wei-Chih Wang Department of Power Mechanical Engineering National TsingHua University W.Wang 1 Week 11 • Course Website: http://courses.washington.edu/me557/sensors • Reading Materials: - Week 11 reading materials are from: http://courses.washington.edu/me557/readings/ • H3 # 3 assigned due next week (week 12) • Sign up to do Lab 2 next two weeks • Final Project proposal: Due Monday Week 13 • Set up a time to meet for final project Week 12 (11/27) • Oral Presentation on 12/23, Final report due 1/7 5PM. w.wang 2 Last Week • Light sources - Chemistry 101, orbital model-> energy gap model (light in quantum), spectrum in energy gap - Broad band light sources ( Orbital energy model, quantum theory, incandescent filament, gas discharge, LED) - LED (diode, diode equation, energy gap equation, threshold voltage, device efficiency, junction capacitance, emission pattern, RGB LED, OLED) - Narrow band light source (laser, Coherence, lasing principle, population inversion in different lasing medium- ion, molecular and atom gas laser, liquid, solid and semiconductor lasers, laser resonating cavity- monochromatic light, basic laser constitutive parameters) w.wang 3 This Week • Photodetectors - Photoemmissive Cells - Semiconductor Photoelectric Transducer (diode equation, energy gap equation, reviser bias voltage, quantum efficiency, responsivity, junction capacitance, detector angular response, temperature effect, different detector operating mode, noises in detectors, photoconductive, photovoltaic, photodiode, PIN, APD, PDA, PSD, CCD, CMOS detectors) - Thermal detectors (IR and THz detectors) w.wang 4 Materials Covered • Radiometry - Radiant Flux - Radiant Intensity - Irradiance - Radiance • Photometry - luminous Flux - luminous Intensity - Illuminance - luminance Conversion from radiometric and photometric W.Wang 5 Radiometry Radiometry is the detection and measurement of light waves in the optical portion of the electromagnetic spectrum which is further divided into ultraviolet, visible, and infrared light.
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