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Introduction to Measurement Quantities Training Level: BASIC

Introduction to Measurement Quantities Training Level: BASIC. Dr. Richard Young Optronic Laboratories, Inc. Techniques & Types of Measurement. Several types of light measurement are possible. These define WHAT you measure.

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Introduction to Measurement Quantities Training Level: BASIC

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  1. Introduction to Measurement QuantitiesTraining Level: BASIC Dr. Richard Young Optronic Laboratories, Inc.

  2. Techniques & Types of Measurement Several types of light measurement are possible. These define WHAT you measure. For each type of measurement, there are several possible techniques. These define HOW you measure.

  3. Techniques=how Photometry & colorimetry Radiometry Spectroradiometry Types=what Total Flux Angular Intensity At a surface At the source Techniques & Types of Measurement

  4. Techniques Photometry & colorimetry Types Total Flux Angular Intensity At a surface At the source How does it look to humans? Techniques & Types of Measurement Quantities start with “photopic” or “luminous”

  5. Techniques Radiometry Types Total Flux Angular Intensity At a surface At the source How much energy is produced? Techniques & Types of Measurement Quantities start with “radiometric” or “radiant”

  6. Techniques Spectroradiometry Types Total Flux Angular Intensity At a surface At the source How is the energy distributed? Techniques & Types of Measurement Quantities start with “spectral” or “spectroradiometric”

  7. Techniques Photometry & colorimetry Radiometry Spectroradiometry Types Total Flux Techniques & Types of Measurement Light emitted in ALL directions Quantities end with “flux”

  8. Techniques Photometry & colorimetry Radiometry Spectroradiometry Types Angular Intensity Techniques & Types of Measurement Light emitted in SPECIFIED directions and angles Quantities end with “intensity”

  9. Techniques Photometry & colorimetry Radiometry Spectroradiometry Types At a surface Techniques & Types of Measurement Light falling onto areas of an object Quantities end with “irradiance” or “illuminance”

  10. Techniques Photometry & colorimetry Radiometry Spectroradiometry Types At the source Techniques & Types of Measurement Light emitted from areas within the source Quantities end with “radiance” or “luminance”

  11. Quantities and Units Photometry + Total Flux = Total luminous flux unit: lumen Radiometry + Total Flux = Total radiant flux unit: Watt Spectroradiometry + Total Flux = Total spectral flux unit: Watt/nm

  12. Quantities and Units Photometry + Angular Intensity = Luminous intensity unit: candela = lumen/sr Radiometry + Angular Intensity = Radiant intensity unit: Watt/sr Spectroradiometry + Angular Intensity = Spectroradiometric intensity unit: Watt/(sr nm)

  13. Quantities and Units Photometry + At a surface = Illuminance unit: lux = lumen/m² Radiometry + At a surface = Irradiance unit: Watt/m² Spectroradiometry + At a surface = Spectral irradiance unit: Watt/(m² nm)

  14. Quantities and Units Photometry + At a source = Luminance unit: candela/m² = lumen/(sr m²) Radiometry + At a source = Radiance unit: Watt/(sr m²) Spectroradiometry + At a source = Spectral radiance unit: Watt/(sr m² nm)

  15. Conversion of units • The preceding units are SI units, currently the favored units by all National Standard Laboratories (NIST etc.) • Sometimes older standards or conventions may require values to be reported in different units • Quantities that are of the same technique and type can be converted by multiplying with a constant.

  16. Conversion of units • Sometimes the conversion is because the quantities use different standard units • E.g. using inches instead of meters for measuring length • Sometimes the conversion is because the quantities use sub-units • E.g. millimeters instead of meters

  17. Conversion of units • Common sub-unit prefixes • femto (f), multiplied by 1E-15 • pico (p), multiplied by 1E-12 • nano (n), multiplied by 1E-9 • micro (µ), multiplied by 1E-6 • milli (m), multiplied by 1E-3 • centi (c), multiplied by 1E-2 • deci (d), multiplied by 1E-1 • kilo (k), multiplied by 1E3 • mega (M), multiplied by 1E6 • giga (G), multiplied by 1E9 • tera (T), multiplied by 1E12

  18. cd/m² cd/m² cd/m² cd/m² lux (lm/m²) lux (lm/m²) cd/in² footlambert ((cd/ft²)/p) Lambert ((cd/cm²)/p) stilb (cd/cm²) Footcandle (lm/ft²) phot (lm/cm²) Conversion of units Conversion to older units Convert from to multiply by 6.4516E-4 2.9186E-1 3.1416E-4 1.0000E-4 9.2903E-2 1.0000E-4

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