1. Total Luminous Flux measurement
where:
de =
Km = lm/W
Luminous intensity: I =dF/dW
thus

2. Total luminous flux: goniometric measurement, intensity summing
Surface of a ring around the source:
The luminous flux emitted into this ring (zone):
In is the average luminous intensity in the given zone
Selection of the zones:
Incand lamp: 10°,
LEDs:

3. Total luminous flux: photometer sphere measurement
Photometer (Ulbricht) sphere: Hollow sphere, the inner wall of which is covered by a diffuse, non-selective, high reflectance paint, (), (BaSO4 or PTFE often used).
If a lamp is placed into the middle of the sphere, the indirect illumination (E) on the wall is:
where F is the total luminous flux of the lamp.
Generally substitution with standard is made
The Auxiliary LED is to correct for self-absorption (see later).
If the LED radiates only into one hemisphere, the 2p geometry can be used.
4p geometry
2p geometry

4. Main corrections in sphere photometry
Source self-absorption correction: 4 measurements
Standard lamp in sphere:
Standard lamp on, measured signal: YN
Standard lamp off, Auxiliary lamp on: YAN
Test lamp in sphere:
Test lamp on, measured signal: YT
Test lamp off, Auxiliary lamp on: YAT
Total luminous flux of test lamp:
where FN is the tot.lum.fl. of standard lamp

5. Partial light flux measurement
Partial LED Flux is a quantity used for specific applications of LEDs. It is defined as the flux leaving the LED and propagating within a given cone angle (centered from the LED's mechanical axis) that is determined by a circular aperture of 50 mm diameter and the distance measured from the tip of LED.
where 0°≤ x ≤ 180°