Application Note

Light Emitting Diode

Luminous Flux Measurement

Table of contents
1. Overview................................................... 2
2. Luminous Flux Measurement ................... 2
3. Integrating Sphere Measurement .............. 2
4. Directivity Measurement .......................... 7
5. Traceability ............................................. 13
6. Summary ................................................. 14

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Application Note
1. Overview

Light Emitting Diode

LEDs are used in various applications such as luminaries. In order to meet the performance such as
brightness, color, etc. desired for the chosen application, suitable product design and evaluation
should be selected. Measurement plays an important role in evaluating product performance.
Measurement is fundamental to manufacturing activities because quantitative evaluation can beachieved only by quantifying the product performance through measurement. However, the actual
values obtained from measurement vary depending on various factors such as measurement methods,
equipment, and environments. In order to perform a highly accurate measurement, it is necessary to
fully understand the measurement concept together with the characteristics of LEDs.
This application note explains luminous flux measurement that is generally used to evaluate LEDs,
the precautions, and the traceability system.

2. Luminous Flux Measurement
Luminous flux measurement is generally performed by using either an integrating sphere or adirectivity measurement system. Both of these instruments have their pros and cons as shown in Table
1. Considering these pros and cons, customers should select the appropriate measurement instrument
depending on the type of light source and the characteristics of light that need to be measured. Sections
3 and 4 explain the considerations when selecting the instrument used for luminous flux measurement.
Table 1. Pros and Cons of the Measurement Instruments
Integrating Sphere
Pros

Cons

- Short measurement time
- Dark room and a complicated instrument are
not required- Size of the light source that can be measured
is limited- Measurement errors due to self-absorption of
the light source

Directivity Measurement System- Able to measure directivity characteristics- Able to measure large-sized light sources- Requires a long measurement time
- Requires a dark room and a complicatedinstrument

3. Integrating Sphere Measurement
3.1. Integrating Sphere
An integrating sphere, as its name implies, is an optical measurement instrument with a sphericalshape. The inside surface is covered with a highly reflective coating and the light incident on the innersurface is evenly distributed to the surface by multiple scattering and reflections. By measuring theilluminance of the light evenly distributed to the inner surface, the total luminous flux is obtained
without being affected by the directivity characteristics of the light source (see Figure 1.).
As listed in Table 1, integrating sphere measurement has advantages such as the measurement time isshort, a dark room or a complicated instrument is not required. Due to these advantages, an integrating
sphere is the most widely used instrument for luminous flux measurement. However, since themeasurable size of the light source is limited by the diameter of the integrating sphere, it is suitable
for measuring relatively small light sources. The typical characteristics (luminous flux, chromaticity,

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Application Notecolor rendering, etc.) detailed in the specifications for Nichia’s LEDs are obtained by using an
integrating sphere1.
Detector
BaffleDevice under Test (DUT)/Standard Light Source

Figure 1. Image of an Integrating SphereLight Emitting Diode3.2. Precautions for Luminous Flux Measurement
Figure 2 shows an example of a configuration of an integrating sphere measurement system. The
luminous flux of a device under test (DUT) can be obtained by measuring the light that is sufficiently
diffused and uniformly scattered inside the integrating sphere with a spectroscope or illuminometerand then comparing it with the measured value of a standard light source that has a known reference
value. In an integrating sphere, the direct illumination from the DUT that can cause measurement
errors is shielded from the detector with a baffle. There are various other factors that contribute tomeasurement errors and uncertainties.
This section explains five main factors leading to measurement errors during an integrating spheremeasurement: 1. integrating sphere measurement configurations, 2. sizes of integrating spheres, 3.
self-absorption of the light source, 4. types of standard light sources, and 5. LED temperature
characteristics.
Detector
Optical Fiber Cable

BaffleDevice under Test (DUT)/Standard Light Source
Spectroscope /Illuminometer

Power Supply
Auxiliary Light Source for
Self-absorption Measurement

Figure 2. A Configuration of an Integrating Sphere Measurement System
3.2.1. Integrating Sphere Measurement Configurations
There are two common sphere measurement geometries: 2π and 4π configurations. A 2π configuration
is used for 2π-space (180-degree field) measurement to evaluate a forward emitting light source. On
the other hand, a 4π configuration is used for 4π-space (360-degree field) measurement to evaluate anomnidirectional light source. Since the 2π configuration does not need to measure a backward
emitting light, the diameter of the integrating sphere can be reduced. However, the measurable sizes

1

Instead of using an integrating sphere, other measurement instruments that are correlated with Nichia’s internal standard light source may be used in
Nichia’s sorting process for mass-produced LEDs.

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Application Noteand types of light sources that can be used for this configuration are limited; thus, it is necessary to
select an integrating sphere that is suitable for the directivity.
Figure 3 shows examples of the different integrating sphere measurement configurations. For typicalsurface mount LEDs that emit light only in the forward direction, the measurement can be performed
under the 2π configuration (see Figure 3-a). In the case of conventional luminaires such as
incandescent light bulbs, fluorescent lamps, and discrete LEDs/LED luminaries with a wide
directivity, since these luminaires emit light not only in the forward direction but also in the backward
direction, the measurement under 4π configurations (see Figure 3-b and 3-c) must be performed.
Detector
BaffleLight Emitting DiodeDevice under
Test (DUT)
Auxiliary Light Source for
Self-absorption Measurementa. 2π Configuration for a
Surface Mount LED

b.4π Configuration for a
Conventional Luminairec. 4π Configuration for a Luminairewith a Wide Light Directivity

Figure 3. Images of Integrating Sphere Measurement Configurations
3.2.2. Size of Integrating Sphere
Customers are required to select an integrating sphere that is suitable for the size of the light sourcethat needs to be measured. When measuring an LED that is only a few millimeters in size, customers
should use an integrating sphere with a diameter of several centimeters to several tens of centimeters.
When measuring a large-sized luminaire or a straight tube fluorescent lamp of one meter or longer,
customers should use an integrating sphere with a diameter of two to three meters.
If a light source is too large for the size of the integrating sphere, the number of reflections on the
inner surface may be reduced and the uniformity (measurement accuracy) of the illuminance on the
inner surface may decrease. In addition to this, when the amount of the light absorbed by the surfaceof the light source increases, the measurement accuracy will further decrease (see Section 3.2.3. selfabsorption of a light source). Therefore, IESNA LM79 recommends that the total surface area of alight source should be less than 2% of the total surface area of the integrating sphere under the 4π
configuration. Also, it recommends that the length of a long and narrow light source should be lessthan 2/3 of the diameter of the integrating sphere under the 4π configuration.
Moreover, when the power consumption of a light source is large, the effects of heat generation should
be considered. IESNA LM79 recommends that customers should use an integrating sphere with adiameter of 2m or greater when measuring a light source whose power consumption is 500W.
3.2.3. Self-absorption of a Light Source
When measuring a light source, customers should consider the decrease in the luminous flux due tothe light absorption (self-absorption) on the emitting surface of the light source and the surface of the
housing. If the surface area of the light source is large and/or its housing has colors that absorb more
light such as black, the decrease in the luminous flux will become large. To minimize the effects ofthe self-absorption, it is necessary to apply a self-absorption correction.
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Application Note
Self-absorption correction factors are obtained from Equation 1 by using an auxiliary light source forself-absorption measurement that is positioned separately from the light source (see Figure 2.). The
decrease in the luminous flux due to self-absorption can be corrected by multiplying the measured
value of the light source with the self-absorption correction factor.
Equation 1:α=is,1 / is,0
it,1 / it,0Light Emitting Diode

where:
α = Self-absorption correction factor
is,0 = The output of the detector when the auxiliary light source for self-absorption measurement,
whose relative spectral distribution is the same as the standard light source, is lit without
having the standard light source in the integrating sphere.
is,1 = The output of the detector when the auxiliary light source for self-absorption measurement,
whose relative spectral distribution is the same as the standard light source, is lit when thestandard light source is in the integrating sphere.
it,0 = The output of the detector when the auxiliary light source for self-absorption measurement,
whose relative spectral distribution is the same as the device under test (DUT), is lit
without having the DUT in the integrating sphere.
it,1 = The output of the detector when the auxiliary light source for self-absorption measurement,
whose relative spectral distribution is the same as the device under test (DUT), is lit when
the DUT is in the integrating sphere3.2.4. Types of Standard Light Sources
In order to perform a comparative measurement with a standard light source that has a knownreference value, which is obtained with a standard measurement instrument, customers should selecta standard light source that has similar characteristics to those of the DUT and ensure that the standard
light source is placed in the same position as that of the DUT within an integrating sphere so that theirillumination directions are the same. If the placement location/direction is different between thestandard light source and the DUT, and/or their directivity characteristics and the spectral distribution
characteristics is significantly different between them, the measurement errors tend to become large.
3.2.5. LED Temperature Characteristics
LEDs generate heat while they are emitting light. When the LED junction temperature rises due tothis heat, the optical characteristics change due to the temperature characteristics. However, since the
LED junction temperature can also change depending on external factors such as the PCB on which
the LED is mounted, the measurement environments, etc., the increase in the LED junction
temperature should be minimized to obtain the original performance of the discrete LED.
In order to minimize the increase in the LED junction temperature, it is effective to shorten theillumination time during the measurement. Figure 4 shows the relationships between the LED junction
temperature/luminous flux and the illumination time (pulse width). These graphs indicate that the
shorter the illumination time of the measurement is, the smaller the increase in the LED junction
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Application Notetemperature and the decrease in the luminous flux become. However, it should be noted that even fora very short illumination time of 1msec, a slight decrease in the luminous flux occurs. When operating
an LED under a high current, the amount of heat generated from the LED is larger than that under alow current even though the illumination time is the same, causing the LED junction temperature to
become high.
LED Junction Temperature

Relative Luminous Flux

100

80

80

60

60

40

40

20

20

0

0

120

100

100

80

80

60

60

40

40

20

20

0

0
1000

100

10

1

0.1

0.01

0.001

0.00010.00001

1000

100

10

1

0.1

0.01

0.001

0.00010.00001

Pulse Width (sec.)

Pulse Width (sec.)a. LED Operation under a Low Current

b. LED Operation under a High Current

Figure 4. Relationships between the Junction Temperature/Luminous Flux of NCSW170F LEDs
and the LED Illumination Time (Pulse Widths) at TA = 25˚C
Nichia performs the measurement under the pulse current operation shown in Figure 5 in order tominimize the increase in the LED junction temperature2. The pulse width is 0.05msec, which is very
short, and the duty ratio is 1%. Under this operation, the increase in the LED junction temperature is
extremely small.
Input Current: IF (A)Light Emitting Diode

LED Junction Temperature (˚C)

100

Relative Luminous Flux

120

120

Relative Luminous Flux (%)

LED Junction Temperature (˚C)

120

Relative Luminous Flux (%)

LED Junction Temperature

Item

Symbol/Formula

Value

Pulse Width

PW

0.05 msec

Pulse CycleT

5 msecDuty Ratio

D=PW/T

1%

Time (sec)

Pulse Width: PW

Pulse Cycle: T

Figure 5. Nichia’s Measurement Condition
When customers need to perform a measurement that takes into consideration the increase in the LED
junction temperature, the measurement should be done by using the dedicated power source that isincorporated in the luminaire instead of by using a power source for pulse current measurement.
Before performing this measurement, the luminaire should be operated under the conditions/environments in which the luminaire is actually used (e.g. configuration of the luminaire, installation
direction) for a certain period of time so that the LED junction temperature and the light output
become stable. After confirming those stabilities, the measurement can be performed.

2

The pulse width, the pulse cycle, and the duty ratio specified in Nichia’s specifications vary depending on the LED type.

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Application Note
4. Directivity Measurement

Light Emitting Diode4.1. Directivity Measurement Equipment
Directivity measurement equipment is used to measure the light intensity emitted from the light source
in a particular direction by rotating either its detector or the light source (DUT). The main purpose is
to measure directivity characteristics; however, directivity measurement equipment can also measure
the total luminous flux by measuring the luminous intensity in each particular direction and summingthem up.
Unlike integrating sphere measurements, there are neither measurement errors due to self-absorptionof the light source (DUT) nor effects of heat from the light source on the directivity measurement
equipment. Due to these advantages, directivity measurement equipment is suitable for measuring oflarge-sized and high-power luminaries.
However, measuring with directivity measurement equipment requires a long measurement time andappropriate measurement environments such as a dark room. For this reason, when only luminous
flux needs to be measured, measuring with an integrating sphere is more common since it can be donein a shorter measurement time.

Detector

Figure 6. Image of Directivity Measurement Equipment
4.2. Directivity Characteristics
There are two directivity characteristics: far-field and near-field characteristics. Since themeasurement methods and the properties of the resulting data of these two are different are different,
customers should select either a far-field characteristic measurement or a near-field characteristic
measurement depending on the type of light source or its intended purpose.
4.2.1. Far-field Characteristics
Far-field characteristics are the directivity characteristics when the light source is viewed from a
distance. Far-field characteristics are obtained with a measurement distance that is far enough tosimulate the light source as a point light source. The far-field characteristics are used for various lightsources such as small light sources, which are discrete LEDs, luminaries, and automobile headlight
modules. Generally, directivity characteristics indicate far-field characteristics. The directivity
characteristics detailed in Nichia’s specifications show the far-field characteristics (see Figure 7).

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Relative Emissi(Normalized to pea
相対発光強度(

0.4

0.2

Application Note

0.0
350

400

450

500

550

600

650

700

750

800

Wavelength(nm)波長Directivity1

Directivity
指向特性

-20°

-10°

0°

10°

-30°

TJ =25°C
IFP = 700mA

20°
30°

-40°

40°

Radiation Angle
放射角度

-50°

50°

-60°

60°

-70°

70°

-80°

80°

-90°

90°
1.0

0.5

0.0

0.5

1.0

Relative Illuminance(a.u.)
相対照度Figure 7. An Example of LED Directivity Characteristics* The graphs above show the characteristics for Rnn LEDs of this product.
本特性は演色性ランクRnnに対応しています。

Light Emitting Diode4.2.2. Near-field Characteristics
When measuring near-field characteristics, the light source is regarded as an area light source that hasa size and shape. The luminance distribution within the light emitting area is captured with an image
sensor by changing the direction of the light source. This measurement shows which part of the lightsource each light ray is emitted from and its angular direction; thus, near-field characteristics aremainly measured to create ray data for optical design simulations of light emitting devices such as
LEDs (see Figure 8). Nichia offers ray data for various optical simulation software. Customers cancontact a local Nichia sales representative for details, including available data formats.

Figure 8. An Example of Ray Data Emitted by an LED
4.3. Coordinate Systems for Directivity Measurements
Figure 9 shows the coordinate systems used in directivity measurements. These three types of thecoordinate systems are mainly selected depending on the type of light source that needs to bemeasured and its intended purpose. However, in some measurement instruments, there are limitations
on the available coordinate systems; thus, customers should select a directivity measurement
instrument with this taken into consideration (see Section 4.4. Types and Features of Directivity
Measurement Instruments).
In the θφ coordinate system shown in Fig. 9-a, the direction perpendicular to the emitting surface ofthe light source is the polar axis (i.e. rotation axis), the tilt angle with respect to the polar axis isexpressed as θ and the rotation angle around the polar axis is expressed as φ. The θφ coordinate systemcorresponds to the C-plane system detailed in CIE 121 and is commonly used in directivity
measurements. The θφ coordinate system is available in many directivity measurement instruments.
The other two coordinate systems are the xy coordinate system and the αβ coordinate system whosepolar axis is horizontal to the emitting surface of the light source. The xy coordinate system and αβ
coordinate system correspond to the A-plane and B-plane detailed in CIE 121, respectively.

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Application Note
Polar Axis

θ

β

y

Polar Axis
(θ=0)

x

(x,y)=(0,0)φ

a. θφ Coordinate System(α,β)=(0,0)

b. xy Coordinate SystemαPolar Axis

c. αβ Coordinate System

Figure 9. Coordinate Systems for Directivity Measurements

Light Emitting Diode4.4. Types and Features of Directivity Measurement Instruments
A directivity measurement instrument consists of a detector such as an illuminometer or spectrometerand a goniometer that rotates the light source or the detector. Directivity measurement instruments
are classified into various types depending on the structure and the rotation method of the goniometer.
The typical types of directivity measurement instruments are shown in Figure 10: rotating light source,
rotating detector, and mirror. The features of these three instruments are described in the following
sections.
Fixed Horizontal
Rotation Axis
Rotating Light
SourceFixed Vertical Axis
Fixed Horizontal Axis

Directivity
Measurement
Instrument

Rotating Horizontal
Axis

Near-field
Measurement
Far-field
Measurement

Moving Vertical Plane
Rotating Detector
Opposite Ends ofRotating Arm
Multiple Detectors

Rotating Mirror
MirrorRotating Light Source

Figure 10. Typical Types of Directivity Measurement Instruments (Goniometers)

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Application Note

Light Emitting Diode4.4.1. Rotating Light Source
In a measurement with a rotating light source, the detector is fixed and only the light source is rotatedto measure the directivity characteristics. Depending on the rotation direction of the light source, thisis classified into three types: fixed horizontal rotation axis, fixed vertical axis, and fixed horizontal
axis. In the measurement with the fixed horizontal rotation axis shown in Figure 11-a, the light sourceis positioned on the same horizontal rotation axis as the detector, then the light source rotates on thevertical and horizontal rotation axes; this corresponds to the θφ coordinate system. In themeasurement with the fixed vertical axis shown in Figure 11-b, the light source is positioned on thevertical axis and it rotates horizontally and vertically; this corresponds to the xy coordinate systemand the αβ coordinate system. In a measurement with a fixed horizontal axis, the light source ispositioned on the horizontal axis; this corresponds to the xy coordinate system and the αβ coordinate
system.
Although the structure of the rotating light source is simple, a large and heavy goniometer stage isrequired to reduce vibration from the rotation of the light source. Since the direction of the light sourcechanges significantly during the measurement, the output of the light source is susceptible to theeffects of gravity; thus, where necessary a correction should be applied to the output obtained at themeasurement angle considering the difference from the output obtained at the angle in which the lightsource is actually placed.
Vertical Axis

Vertical Axis
Horizontal Axis
Light Source
Horizontal Axis
Detectora. Fixed Horizontal Rotation Axisb. Fixed Vertical Axis
Figure 11. Example Configurations for Rotating Light Sources
4.4.2. Rotating Detector
In a measurement with a rotating detector, the light source rotates and the detector revolves aroundthe light source to measure the directivity characteristics. Depending on the revolution direction of
the detector, this is classified into four types: rotating horizontal axis, moving vertical plane, opposite
ends of rotating arm, and multiple detectors. As examples, in the measurement with the rotating
horizontal axis shown in Figure 12-a, the detector revolves around the horizontal axis and the lightsource rotates around the vertical axis. In the measurement with the multiple detectors shown in
Figure 12-b, the revolution of the detector is not required since multiple detectors are placed on theorbit around which the light source rotates, reducing the measurement time. Since the distance
between the light source and the detector is short due to this configuration, this measurement is limited
to small-sized light sources; however, the compact measurement system integrated with a detector iseasy to install.
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Application Note

Horizontal Axis
Light Source
Multiple Detectors
Detectora. Rotating Horizontal Axis
b. Multiple Detectors
Figure 12. Example Configurations for Rotating Detectors

Light Emitting Diode4.4.3. Mirror
In a measurement with a mirror, the light reflected by the mirror is measured. Depending on whether
either the mirror or the light source revolves, this is classified into two types: rotating mirror androtating light source (the mirror is fixed). In both of the types, since the optical distance is increasedby the mirror reflection, the actual distance between the light source and the detector can be shortened.
As an example, in the measurement with the rotating mirror shown in Figure 13, the light source
rotates around the vertical axis and the mirror revolves around the light source. In this measurement,
the direct light incident on the detector can cause measurement errors; thus, a light shield should beplaced to block the direct light.
Since a large mirror is used in the measurement, the maintenance is complicated and dust and dirt on
the mirror may lead to measurement errors. In addition, due to the polarization effects induced by the
mirror, using this type of the measurement may not be possible depending on the type of light source.
Vertical Axis
Horizontal Axis
Light Source✕
Detector
MirrorFigure 13. Example Configuration for Mirror
4.5. Precautions for Directivity Measurement
Figure 14 shows an example configuration of a directivity measurement system. A spectroscope orilluminometer connected to the detector measures only light that travels straight from the center ofthe light source. By rotating and revolving the light source and/or detector with a goniometer, the lightemitted from the light source in a particular direction is measured. However, since it is necessary to
do a large number of measurements by changing the measurement angle, the measurement is timeconsuming.

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Application Note
Dark RoomLight Shield
DUT/Light Source

Detector

Goniometer
Power Source

Spectroscope/Illuminometer

Figure 14. Example Configuration for Light Distribution Measurement System

Light Emitting Diode

This section explains the possible factors that can cause measurement errors in the directivity
measurements: 1. measurement angle, 2. measurement distance, 3. types of standard light sources,and 4. LED temperature characteristics.
4.5.1. Measurement Angle
If the number of the measurements by changing the measurement angle is insufficient, accurate
directivity characteristics and luminous flux cannot be obtained. By narrowing the measurement angle
and increasing the number of measurements, the measurement accuracy can be improved; however,when the number of the measurements is doubled, the measurement time is also doubled. Therefore,
it is not efficient to increase the number of the measurements without careful consideration. To
conduct an efficient measurement, it is necessary to optimize the measurement angle (e.g. widening
the measurement angle in the illuminated area with a small change in brightness) depending on the
directivity of the luminaire that needs to be measured.
4.5.2. Measurement Distance
When performing a far-field measurement, a sufficient measurement distance should be maintained
between the light source and the detector. When a far-field measurement is performed considering theluminaire as a point light source, a distance that is at least five times longer than the longitudinallength of the light emitting surface of the luminaire is required.
4.5.3. Types of Standard Light Sources
In a similar manner to an integrating sphere measurement, in order to perform a comparative
measurement with a standard light source that has a known reference value, which is obtained with astandard measurement instrument, customers should select a light source that has similar
characteristics to those of the DUT (see Section 3.2.4. Types of Standard Light Sources).
4.5.4. LED Temperature Characteristics
In a similar manner to an integrating sphere measurement, customers should consider LED
temperature characteristics (see Section 3.2.5. LED Temperature Characteristics). It is necessary tooperate an LED under a pulse operation that is less susceptible to heat or to thermally saturate an LED
sufficiently so that the brightness does not change during the measurement. In addition, since it takes
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Application Note
some time to measure directivity characteristics, the temperature of the dark room should becontrolled to maintain a constant temperature to avoid temperature changes due to time elapsed.
When a measurement with a rotating light source (see Section 4.4.1. Rotating Light Source) is
performed while the light source is saturated, the light source is rotated at different angles during themeasurement; this may cause the original heat dissipation performance to not be achieved. In thiscase, it is necessary to apply a correction against the measured values using the difference between
the brightness obtained at the original illuminating direction of the light source and the brightness
obtained at the measurement angle.

5. Traceability

Light Emitting Diode5.1. Traceability and Uncertainty
Calibration of measurement instruments is essential for accurate measurements. Measurement
instruments are calibrated using a standard measurement instrument and this standard measurement
instrument is calibrated by a higher-level standard instrument that has been calibrated to achieve
further accuracy. Through this hierarchical calibration system, the measurement instrument is
eventually traceable to a national standard instrument (or an international standard instrument). This
chain system of calibrations is referred to as traceability.
Traceability is defined by JIS Z 8103 as a “property of a measurement result whereby the result canbe related to a reference through a documented unbroken chain of calibrations, each contributing to
the measurement uncertainty”. Therefore, the established calibration of traceability must meet theconditions such as “clarification of uncertainty at each calibration hierarchy”, “unbroken traceability
chain to a national measurement standard”, and “documentation of calibration procedures and results”.
Uncertainty is also defined by JIS Z 8103 as a “parameter, associated with the result of a measurement,that characterizes the dispersion of the values that could reasonably be attributed to the measurand”
and is an indicator of how far a measured value obtained from a measurement is from the true value(dispersion). The possible factors that can cause uncertainty during luminous flux measurement
include individual differences between measurement instruments, measurement noises, andmeasurement environments (temperature and humidity).
5.2. Nichia’s Traceability System
Figure 15 illustrates Nichia’s traceability system. Uncertainties contained in the characteristics of theLEDs that are shipped from Nichia as finished products includes all uncertainties existing in thehierarchical calibration from a national standard instrument to Nichia’s sorting machines used in mass
production3. Note that this uncertainty represents the correlation to a national standard instrument anddoes not represent the difference between the characteristics of the LEDs and the measurement values
obtained by other measurement organizations that are outside of Nichia’s traceability system.

3

The tolerances listed in Nichia’s specifications have been determined based on the uncertainties within Nichia’s traceability system.

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Application Note
National Standard Instrument
A standard light source is prepared.
Internal standard instruments are calibrated
with the standard light source.

NichiaInternal Standard Instruments
Reference light sources are prepared.
Sorting machines are calibrated with
the internal standard instrument.

Light Emitting Diode

Sorting Machine for
Mass Production

Finished Products

Sorting Machine for
Mass Production

・・・

・・・

・・・

Figure 15. Nichia’s Traceability System

6. Summary
In this application note, Nichia provided luminous flux measurement methods by using integrating
spheres and directivity measurement instruments. Since both types of measurement instruments havetheir pros and cons, customers should select the appropriate measurement instrument depending on
the characteristics of the light source that need to be measured and the purpose of measurement.
This application note also explained that there are various factors that contribute to measurement
errors. Nichia recommends establishing appropriate measurement environments and procedures tominimize measurement errors and designing the chosen application with sufficient margins for theintended performance.

References:-

IESNA LM79 IESNA Approved Method for the Electrical and Photometric Measurements of Solid-State Lighting Products-

CIE 121 The Photometry and Goniophotometry of Luminaires-

JIS C 8105-5 Luminaires -- Part 5:Gonio-photometric methods-

JIS C 8152 Photometry of white light emitting diode for general lighting-

JIS Z 8103 Glossary of Terms Used in Measurement

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Application Note

Light Emitting Diode

Disclaimer
This application note is a controlled document of Nichia Corporation (Nichia) published to provide
technical information/data for reference purposes only. By using this application note, the user agrees
to the following: This application note has been prepared solely for reference on the subject matters incorporated
within it and Nichia makes no guarantee that customers will see the same results for their chosen
application.
 The information/data contained herein are only typical examples of performances and/or
applications for the product. Nichia does not provide any guarantees or grant any license underor immunity from any intellectual property rights or other rights held by Nichia or third parties.
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