Jadak Photo Research SpectraScan PR-7 Series, User Manual

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Chapter 11
– Luminous / Radiant Flux
101
Chapter - 11 L
UMINOUS
/ R
ADIANT
F
LUX
Luminous flux (given in lumens) is the basic unit of photometry and is calculated from radiant flux (given in
watts). It represents the total luminous or radiant output of a source over 360°. Typical applications for
luminous flux measurements include florescent or incandescent lamps and LEDs, where it is required to know
the total output of the source.
The correct way to measure luminous (or radiant) flux is by utilizing an integrating sphere. Integrating spheres
possess the ability of (as the name implies) integrating or homogenizing the light over the entire 360° emittance
pattern of the device under test.
For the PR-7XX, the IS-730 integrating sphere is available for measuring the luminous and radiant flux of dual-
lead LEDs.
O
VERVIEW
FIGURE 84 - IS-730 OUTER VIEW
The IS-730 is a 3-inch sphere designed to measure the total luminous flux (lumens) or radiant flux (watts) of
LEDs or other small sources such as miniature lamps. This accessory consists of a sphere with an internal
baffle and LED Mounting Tube (See Figure 85). During operation, the LED is inserted into the interior end of
the Mounting Tube, the Adjustment Screw is set so that the tip of the LED protrudes precisely 0.100 inches into
the sphere, and the measurement is conducted. The power cables for the LED (plus and minus current) are
connected via mini banana jacks located on the anterior end of the mounting tube.