Jadak Photo Research SpectraScan PR-7 Series, User Manual

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Chapter 7
– File Settings
86
H
OW TO
R
ECALL MEASUREMENTS STORED ON THE
SD
CARD
Measurements stored on the SD card can be recalled in three ways.
1. Using the explorer settings, see section for more information,
2. Using SpectraWin 2 (optional)
Import feature, refer to SpectraWin 2 manual for more information
3. Using the in-built Remote Control Mode capability, see Remote Control Command Detail section for
more information.
M
EASUREMENT
T
YPES
The PR-7XX can make of measurements of different radiometric and photometric units depending on the type
of accessory being utilized. They include Lumens (Watts), Luminous Intensity (Radiant Intensity), Luminous
Flux (Radiant Flux) Luminance (Radiance) and Illuminance (Irradiance). The most typical measurement is one
of radiance in watts / steradian / meter² and luminance in footlamberts and cd/m².
L
UMINANCE
/ R
ADIANCE
Luminance is defined as luminous flux (lumens) per solid angle (steradians) per unit area being emitted in a
given direction and is calculated from
Radiance (watts/steradian/meter² ) .
The SI equation for luminance is cd/m² (lumens/steradian/meter²) . The English equivalent is footlamberts (1/

lumens/steradian/foot²) . The relationship between cd/m² and footlamberts is:
1 footlambert = 3.426 cd/m².
Luminance is measured whenever it is desirable to know the photometric brightness of self-emitting devices,
transmissive objects or a surface upon which light is being reflected. Typical applications include display
brightness, projector screen brightness etc. Ideally, the object being measured exhibits a uniform emittance
pattern over the entire emitting surface.
Luminance measurements using the PR-7XX are made with any of the objective lenses, or with the fiber probe
(FP-730) or with the luminance probe (LA-730) only. The lenses include the MS-75, SL-0.5X, SL-1X, SL-2.5X
and SL-5X.
In the following exampl
e, let’s say a projector screen or reflectance standard such as the RS-3 or SRS-3 or
equivalent, the light incident on the surface is illuminance, and the light being reflected from the surface is
luminance.