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ELEC-E8700
Principles and Fundamentals of Lighting
I-II/2016-2017
Laboratory work
Lab 2 - Integrating sphere (lamp measurement and characterization)
Aalto University, autumn 2016
ELEC-E8700 PRINCIPLES AND FUNDAMENTALS OF LIGHTING
I-II/2016-2017
LABORATORY WORK 2 – INTEGRATING SPHERE
1 Introduction
The laboratory work is done in groups of 3-4 persons. Each member of the group must
return his own report on the work. The report should be submit in MyCourses workspace
within a week after the laboratory work. Participation in the laboratory session and
accepted laboratory report are mandatory requirements to pass this course.
1.1 Measurement of luminous flux
According to the respective standard, the measurement of the luminous flux of new lamps
should be is carried out after 100 hours of operation. The ambient temperature of the
measurement place should be 25 ± 1 °C.
The supply voltage must be stabilized with ± 0.5% accuracy and ± 0.2% during the
measurement. The current consumption of measuring devices connected in parallel with
the lamp must not exceed more than 3% of the rated current of the lamp and the voltage
drop caused by measuring devices connected in series with the lamp must not exceed 2%
of the nominal lamp voltage. Lamp input power must not deviate by more than 5% + 0.5 W
of the declared value on lamp’s data sheet. After the 100 hours of operation the luminous
flux should be at least 90% of the declared value on the lamp’s data sheet.
The luminous flux measurements are performed in integrating spheres (also known as
Ulbricht spheres). The diameter of the integrating sphere should be at least 1.2 ... 1.5
times the length of the lamp (e.g. the length of fluorescent lamp) and the total surface area
of the lamp must not exceed 2% of the inner surface area of the integrating sphere, unless
an error compensation method is used (Equation 1). In particular, especial attention should
be given to light absorption caused by additional materials used for mechanical fixation of
the lamp inside the sphere, connection wires or power supplies. Ideally these materials
and equipments should have the same color properties as the inner surface of the
integrating sphere. The lamp is placed in the center of the sphere and the white baffle dish
is used to prevent transmission of light directly from a light source to the light sensor
located in the entrance door on the sphere surface.
The influence of light absorption and physical geometry (e.g. dimensions, form and shape)
of the measured lamp mounted inside the sphere on the luminous flux measurement is
taken into account by using an auxiliary lamp and by carrying out the following
measurements:
E1 – Reference lamp inside the sphere (ON), auxiliary lamp (OFF)
E2 – Reference lamp inside the sphere (OFF), auxiliary lamp (ON)
E3 – Measured lamp inside the sphere (OFF), auxiliary lamp (ON)
E4 – Measured lamp inside the sphere (ON), auxiliary lamp (OFF)
The luminous flux of the measured lamp (x) is given by the following expression:
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ELEC-E8700 PRINCIPLES AND FUNDAMENTALS OF LIGHTING
I-II/2016-2017
LABORATORY WORK 2 – INTEGRATING SPHERE
𝐸
𝐸
Φ𝑥 = 𝐸2 × 𝐸4 × Φ0
3
1
(1)
Where:
Ф0 is the luminous flux of the reference lamp
2 Measurements
When the measurement setting is modified the voltages must be switched off! The polarity
of the voltage must be checked before switching on, especially for the E27-based lamps.
Also checks before switching on that the voltage is correct and direct current is used.
Greater currents may damage the special lamps. Note also the position of the current
limiter before measuring.
The spectral photometer Ocean Optics HR 4000 is a sensitive instrument. Handle it
carefully! The “dark scan” function must be used before each measurement. Use the
provided form (i.e. Table 1) to record the measurements and take three saved spectral
files with you after the measurements.
1.1 Measure the relative luminous flux of the reference lamp (“A” 20W G4 Halogen)
with the nominal voltage (12V). Switch off the lamp and do the auxiliary lamp
measurement as well.
1.2 a) Measure the relative luminous flux of the incandescent lamp (“GLS A” 25W E27)
using the nominal voltage (12V). Save the spectrum file.
b) Investigate the properties of “GLS A” depend when the supply voltage is varied.
U = Un ± 0,5V.
1.3 a) Measure the relative luminous flux of the fluorescent lamp (“CFL A” 11W E27)
using the nominal voltage (12V). Save the spectrum file.
b) Investigate the properties of “CFL A” when the supply voltage is varied. U = Un ±
0,5V. After adjusting the voltage, give the lamp enough time to stabilize.
1.4 a) Measure the relative luminous flux of the LED lamp (”LED A” 3W GX5.3) using
the nominal voltage (12V). Save the spectrum file.
b) Investigate the properties of “LED A” when the supply voltage is varied. U = Un ±
0,5V.
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ELEC-E8700 PRINCIPLES AND FUNDAMENTALS OF LIGHTING
I-II/2016-2017
LABORATORY WORK 2 – INTEGRATING SPHERE
Student name:
Student number:
Group:
Date of the lab work:
Report
Attach the original measurement results (Table 1) or a copy to this report.
2.1 Calculate the luminous flux and luminous efficacy of GLS A.
Present graphically how the properties of the lamp (Φ, P, Φ/P, I) depend (%) on the supply
voltage.
Comment the results.
2.2 Calculate the luminous flux and luminous efficacy of CFL A.
Present graphically how the properties of the lamp (Φ, P, Φ/P, I) depend (%) on the supply
voltage.
Comment the results.
2.3 Calculate the luminous flux and luminous efficacy of LED A.
Present graphically how the properties of the lamp (Φ, P, Φ/P, I) depend (%) on the supply
voltage.
Comment the results.
2.4 Compare the luminous efficacies of the lamps.
2.5 How did dimming affect the colour properties of the lamp?
2.6 What could cause errors in the measurement of light output?
2.7 What factors affect the actual efficacy in the real applications?
2.8 How the efficiency of a luminaire could have been measured in the Ulbricht sphere?
2.9 How well do the incandescent, compact fluorescent and LED lamps suit for use in homes.
What can you say about colour properties and colour temperatures?
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ELEC-E8700 PRINCIPLES AND FUNDAMENTALS OF LIGHTING
I-II/2016-2017
LABORATORY WORK 2 – INTEGRATING SPHERE
Table 1 – Measurement results
U
I
P
CCT
E
Φ
A (normal lamp)
Un (12V)
Auxiliary lamp
(12V)
GLS A
Un (12V)
Un +0.5V
Un -0.5V
Auxiliary lamp
(12V)
CFL A
Un (12V)
Un +0.5V
Un -0.5V
Auxiliary lamp
(12V)
LED A
Un (12V)
Un +0.5V
Un -0.5V
Auxiliary lamp
(12V)
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