SOLUTIONS FOR IES/LDT FILE CREATION

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TODAY S AGENDA Solutions for IES/LDT File Creation: Conventional Goniophotometry The Near-Field Measurement System The Measurement Process Types of Data Acquired: Near-field data Far-field data Software Demo Working with Radiant PM-NFMS Software How to export IES/LDT files from measured data Comments on the LM-79 Method 3

IES/LDT FILE CREATION FOR LIGHT SOURCE CHARACTERIZATION 4

PHOTOMETRIC DATA FILES ASCII (delimited text) file containing luminous intensity data for a light source Used to observe total light output and angular spread of output of a source for lighting design Data can be used to generate polar and cone diagrams in common optical design programs File formats: IES (*.ies) EULUMDAT (*.LDT) Illuminating Engineering Society of North America (IESNA) created standard LM-63-86 IES Recommended Standard File Format for Electronic Transfer of Photometric Data IES most common photometric file format in North America; EULUMDAT standard in Europe 5

PHOTOMETRIC DATA FILES 3D Diagram from IES Data IES Data: Luminous Intensity Distribution 6

CREATING IES FILES IES/LDT files are generated using near-field and far-field techniques in the lab Dark room needed for accurate measurement Size of lab space depends on measurement solution Generally two solutions available: Conventional Goniophotometry (Far-Field Measurement System) Near-Field Measurement Systems 7

WHAT TYPES OF DATA ARE THERE? NEAR-FIELD LED strip FAR FIELD Near-Field: Analyze millions of points at a time Goniometer + (imaging photometer or- imaging colorimeter) Small space needed for measurements Far-Field: Analyze one point at a time Goniometer + spot meter (spectrometer or photometer) Larger space needed for measurements 8

WHAT SOLUTIONS ARE AVAILABLE? Source is mounted on a goniometer and: Is rotated in two axes allowing entire intensity distribution to be sampled, or Conventional Goniophotometry Source is fixed, with a flying mirror directing light to the sensor Stationary spot photometer placed in farfield Luminous intensity distribution created from point measurements Light Source Two-axis goniometer Photodetector or radiometer Near field measurements must be completed using separate instrumentation 9

WHAT SOLUTIONS ARE AVAILABLE? Advantages: Accurate Generates IES/Far-field data LM-79 Certified Conventional Goniophotometry Disadvantages: Expensive Requires a very large lab space Increased possibility for stray light No near-field data capability Time-consuming (depends on 3 rd party lab turnaround time) Cost may be reduced by sending luminaires to a testing lab, but this requires weeks to months of turnaround time. 10

WHAT SOLUTIONS ARE AVAILABLE? Near-Field Measurement Systems (NFMS) Advantages: Cost Effective Accurate Near- and Far-Field Data Generate IES/LDT Files Minimal lab space (5 to ~20 feet) Time efficient (in-house: 1-2.5 hrs/device) Disadvantages: Not LM-79 Certified (discussion to come) 11

THE RADIANT SOLUTION: PM-NFMS 12

HOW DOES THE NFMS WORK? PM-NFMS: ProMetric Near-Field Measurement System Source is mounted on a two-axis goniometer Stationary imaging colorimeter placed in near-field views source directly Source is rotated in two axes, and luminance is measured at all angles 13

NFMS MEASUREMENT THEORY Light source is not treated as a point source Spatial information recorded Luminance and color measurements are recorded at each angle Software produces powerful model of luminance and chromaticity as a function of angle 14

WHAT TYPES OF DATA ARE THERE? Far-Field: Luminous Intensity Luminous Flux in a given direction I(q,f) By definition a far-field measurement assumes the source is a point Near-Field: Luminance Luminous flux in a given direction per unit area L(x, y, q, f) By definition a near-field measurement considers the spatial extent of the source More complete than far-field data alone 15

SYSTEM REQUIREMENTS AND PERFORMANCE Traditional Far-field System Need for stray light control No ray tracing to far-field Minimal source information Large lab area needed, proportional to source size Near-field System Minimal area required for measurement, no tunnel needed Data can be used in optical ray trace software to accurately describe illuminance distributions at any distance Luminance data obtained (provides unified glare rating measurement) 16

WHAT DO WE MEASURE? Near-Field Data More detailed information than far-field only techniques Z Light leaves an extended source not a point source Predicts illumination pattern at any distance from the source X Y Measuring near-field gives near and far-field data. 17

NEAR- AND FAR-FIELD DISTRIBUTIONS Frame is designed to hold large or small luminaires Near and far field models can be produced in one scan Near Field (As measured) Far Field (Ray-Traced to infinity) 18

RESULTING DATA SETS Luminance Chromaticity (spatially resolved) Luminous Intensity Illuminance at a given distance Near field distribution Far-field distribution (ray-traced) Spectra (with optional SP-1000) 19

VIEW ANGLE PERFORMANCE Luminance Intensity Chromaticity Spectrum (requires optional spectrometer) Correlated color temperature (CCT) Color rendering index (requires optional spectrometer) Unified glare rating 20

DATA OUTPUT IES, EULUMDAT, and Radiant Source Model output formats Data can easily be imported into various optical modeling software programs 21

OPTICAL MODELING SOFTWARE PROGRAMS ASAP FRED LightTools OpticStudio (ZEMAX) Opticad SPEOS TracePro Photopia IES TM-25 22

ILLUMINATION DISTRIBUTIONS Simulate illumination at a given distance using the ray sets, accurate in both space and angle Example: Simulate illumination of countertop with under-cabinet lighting Cannot be done with IES/LDT file 23

HOW DOES THE NFMS STACK UP? Complete All of the image data can be retained for further analysis Provides extensive data set: Near field/far field Illumination IES EULUMDAT (LDT) Optional spectra Cost-effective Fast results; much less expensive than a flying mirror photogoniometer Can use camera for other measurements (illuminance) Accurate Proven to be within ~1% of reference measurements Intensity (cd) Far-Field Intensity at 3.4m from Source 40,000 30,000 20,000 10,000 0 Spot Goniophotometer Near-field FPMS-LI Goniometer Imaging Colorimeter -20-15 -10-5 0 5 10 15 20 Angle (degrees) 24

APPLICATIONS OF RADIANT S NFMS 25

TYPICAL APPLICATIONS View angle performance Optical Modeling: Near- and far-field luminous intensity distribution for large light sources (in compact lab spaces) Illumination distribution measurement for large light sources Illumination modeling of room and architectural lighting systems 26

INDOOR/OUTDOOR LIGHTING IES and EULUMDAT (LDT) file export formats 27

WHAT ABOUT THE LM-79 METHOD? Source is not aligned as it would be used with respect to gravity Very little difference exists between the output of a lamp aligned in one orientation vs. another Cannot certify, but can create IES/LDT files that are just as accurate NFMS is not intended to be a certification system Value lies in precertification testing Know that you will pass LM-79 before you send out for certification testing Reduces time and cost Generates IES/LDT files needed for all lighting systems Can create ray files, for spatial modeling of light exiting the lamp 28

SUMMARY Photometric data files (IES and LDT) offer critical light source measurement data for lighting design, such as luminous intensity, overall output, and angular spread. Two solutions for IES/LDT generation are Conventional Goniophotometers and Near- Field Measurement Systems. Near-Field Measurement Systems have significant advantages over conventional goniophotometers for near- and far-field data acquisition in terms of cost, speed, size, and lab space, and offer equal accuracy. Radiant s PM-NFMS solution consists of an imaging colorimeter, two-axis goniometer, and PM-NFMS Software for generating IES, EULUMDAT, and Radiant Source Model files. PM-NFMS Software creates photometric data files in IES/LDT format, which can be output as polar and cone diagrams using any common optical design program. 29