Introduction to Measurement Quantities Training Level: BASIC

1
Introduction to Measurement Quantities Training
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 Types of Measurement

• Techniqueshow
• Photometry colorimetry
• Radiometry
• Spectroradiometry

• Typeswhat
• Total Flux
• Angular Intensity
• At a surface
• At the source

4
Techniques Types of Measurement

• Techniques
• Photometry colorimetry

• Types
• Total Flux
• Angular Intensity
• At a surface
• At the source

Quantities start with photopic or luminous
5
Techniques Types of Measurement

• Techniques
• Radiometry

• Types
• Total Flux
• Angular Intensity
• At a surface
• At the source

Quantities start with radiometric or radiant
6
Techniques Types of Measurement

• Techniques
• Spectroradiometry

• Types
• Total Flux
• Angular Intensity
• At a surface
• At the source

Quantities start with spectral or
spectroradiometric
7
Techniques Types of Measurement

• Techniques
• Photometry colorimetry
• Radiometry
• Spectroradiometry

• Types
• Total Flux

Light emitted in ALL directions
Quantities end with flux
8
Techniques Types of Measurement

• Techniques
• Photometry colorimetry
• Radiometry
• Spectroradiometry

• Types
• Angular Intensity

Light emitted in SPECIFIED directions and angles
Quantities end with intensity
9
Techniques Types of Measurement

• Techniques
• Photometry colorimetry
• Radiometry
• Spectroradiometry

• Types
• At a surface

Light falling onto areas of an object
Quantities end with irradiance or illuminance
10
Techniques Types of Measurement

• Techniques
• Photometry colorimetry
• Radiometry
• Spectroradiometry

• Types
• At the source

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
Conversion of units
Conversion to older units
Convert from to multiply by

• 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)

6.4516E-4 2.9186E-1 3.1416E-4 1.0000E-4 9.2903E-2
1.0000E-4