The photometric specifications of LEDs must commonly meet very high tolerance requirements even for non-specialist applications such as general and automotive lighting. This is often a problem since the manufacturing tolerances of LEDs can be higher than those permitted in the applications. The tolerance limits offered by LED manufacturers’ intensity and color based binning are only applicable if the operating conditions are similar to those in the binning tests. Therefore, manufacturers incorporating LEDs into their products require devices that can accurately measure the precise in-situ photometric performance of LEDs. 


Compact spectral radiometer

The compact BTS256-LED enables you to conveniently measure the luminous flux, spectrum, color, and color rendering indices of single LEDs. One special feature is the conical measurement port of the device. The ability to perform measurements of onboard LEDs makes it possible to also include thermal effects in the measurement. The luminous flux, color, color rendering indices and spectrum of an LED are all typically measured within a few seconds. The device is therefore ideal for inspection of incoming products as well as the quality control in production processes. It can also be very useful in the design department. 

The BTS256-LED comes in a compact aluminum housing and offers all functions that are necessary for precise measurement of the luminous flux, spectrum, color, and color rendering indices. For greatest accuracy and versatility, this device is based on a BiTec light sensor that consists of a V-lambda-filtered Si photodiode and a spectrometer unit that has a CMOS diode array. Si photodiodes are unsurpassed in terms of dynamic range, linearity, and speed. The CMOS diode array-based spectrometer guarantees precise measurement data of the luminous spectrum which is used to determine the color values. The combination of the two detectors enables mutual correction (see article on the BTS technology) for greater precision. This also makes it possible to perform accurate, time-synchronized measurements, e.g., of PWM signals. One cutting-edge feature of the BTS256-LED is its remote-controlled shutter for dark current compensation of the array as well as its software-controlled auxiliary lamp for compensation of light absorbed by the measurement samples (self-absorption correction). The remote control takes place via a USB 2.0 interface using the supplied S-BTS256 software.


Calibration

One essential quality of photometric devices is their precise and traceable calibration. Calibration of the BTS256-LED is performed in Gigahertz-Optik’s calibration laboratory that is accredited by DAkkS (D-K-15047-01-00) for the spectral responsivity and spectral irradiance according to ISO/IEC 17025. The device has two calibrations: one is done using a specially developed reference lamp offering 2pi illumination which enables precise measurement of the luminous flux of diffusely emitting LEDs. The second calibration is for sources that have narrower illumination characteristics.


Options for the BTS256-LED

-       Software development kit to enable users to integrate the device in their own software

-       Extension to the BTS256-LED Plus Concept  (for illuminance and luminous intensity) using other components

 

BTS256-LED for measurement of the luminous flux, spectrum, color, and color rendering index of single LEDs

1) BTS256-LED housing 2) 50mm integrating sphere with synthetic coating 3) Conical measurement port 4) Precision bayonet Mount 5) Test LED on a circuit board (device under test) 6) Remote-controlled auxiliary lamp 7) BiTec sensor with Si photodiode, CMOS diode array spectrometer and shutter 8) Microprocessor 9) USB 2.0 interface

The conical measurement port is placed over the test LED and detects all the radiation in a 2pi space

Graphical view of the spectrum

S-BTS256 user software with modular desktop setup

CIE 1976 chromaticity table with binning fields

CRI Bar Plot

General
Short description

Spectroradiometer for measurement of the luminous flux, spectrum, color, and color rendering indices of single LEDs

Main features

Compact measurement device with internal integrating sphere, BiTec light sensor, remote-controlled auxiliary lamp and shutter. Fast data logger for the luminous flux. Software

Range of measurement

Luminous flux: 10 mlm - 1100 lm, spectral range: 380 nm - 750 nm, bandwidth: 5 nm with optical bandwidth correction according to CIE 214

Typical applications

Goods-in inspection of individual LEDs, quality assurance of assembled LEDs in production processes, Research and development testing.

Calibration

For diffuse emitting and narrow beam LEDs. Factory calibration. Traceable to international calibration standards.

Product
Light sensor

Bi-Technology sensor with a photometric broadband detector and a array spectrometer. Integrated aperture for automatic dark signal adjustment.

Input optics

Integrating sphere with synthetic ODM98 coating and protective window at the sphere port. Cone adapter coated with ODP97 for radiation absorption. 10mm diameter measurement port. LED auxiliary lamp. 

Adapter change effect - +/- 0.5%
Max. xy responsivity deviation of the 10mm measurement port +/- 2%
Max. z responsivity deviation of the 10mm measurement port +/-2% (1 to 11mm)

Calibration uncertainty

+/-8% for luminous flux

Spectral Detector
Chip

CMOS diode array

Wavelength Range

(380 - 750) nm

Optical Bandwidth

5 nm

Data Resolution

1 nm

Integration Time

(5.2 - 30000) ms

Shutter

Automatic aperture for dark signal measurements with the same integration time as that of light measurements. Aperture delay = 100ms .

Typ. Measurement Time

1100 lm ≤ 5ms (white light)

10 mlm ≤ 30s (white light)

Peak Wavelength

± 0.5 nm

Dominant Wavelength

± 1 nm

Δx, Δy reproducibility

± 0.0001 (Standard illuminant type A)

± 0.0002 (LED)

Δx, Δy uncertainty

± 0.002 (Standard illuminant type A)

± 0.005 (typ. LED)

CCT measurement range

(1700 - 17000) K

ΔCCT

± 50K (standard illuminant type A)

± 3% (depending on the LED spectrum)

CRI (color rendering index)

Ra and R1 to R15

Stray Light

6E-4 (Blue LED)

6E-4 (Green LED)

6E-4 (Red LED)

1E-3 (White LED)

Integral Detector
Filter

Spectral responsivity with fine CIE photometric matching. Online correction of the photometric matching through spectral measurement data (spectral missmatch factor correction).

f1'

≤6% (uncorrected)

≤3% (f1' a*(sz(λ)) respectively F*(sz(λ)) corrected by spectral data, done automatically by BTS technology)

Max. measurable luminous flux

70000 lm

Noise equivalent luminous flux

0.05 mlm

Resolution

12Bit

Measurement Time

(0.1 - 6000) ms

Graphs
spectral responsivity

specral sensitivity BTS256 LED

Miscellaneous
Microprocessor

16Bit, 25ns instruction cycle time

Power

5VDC to 7VDC, 250mA peak during capacitor charging of the auxiliary lamp

Interface

USB 2.0 (Type B USB port)

Temperature

Operation: 10 to 30°C

Storage: -10 to 50°C

Dimensions

160mm x 85mm x 60mm (Length x Width x Height)

Weight

500g

Casing

Plastic hard-top casing, 333 x 280 x 70mm, 650g

Option: 210mm Integrating Sphere (UMBB-210)
Measurement Range Luminous Flux

(0.35 - 35000) lm

Sphere diameter

210 mm

Calibration

Luminous flux: ± 8%

Option: 500mm Integrating Sphere (UMBB-500)
Measurement Range Luminous Flux

(1.2 - 120000) lm

Sphere diameter

500 mm

Calibration

Luminous flux: ± 8%

Option: 1000mm Integrating Sphere (UMTB-1000-HFT)
Measurement Range Luminous Flux

(3 - 300000) lm

Sphere diameter

1000 mm

Calibration

Luminous flux: ± 8%

Option: Irradiance (DA)
Measurement Range Illuminance

(0.2 - 25000) lx

Calibration

± 4 %

Option: Goniometer (GB-GD-360-RB40)
Luminous intensity

(2E-1 - 2E8) cd ; by 1m measurement distance

Calibration

Luminous intensity: ± 4 %

Type Description File-Type Download
Datasheet BTS256-LED PDF
Produktname Product Image Description Show product
BTS256-LED-IB Compact Bi-Tec measurement device for the measurement of ILED-B

Features: Bajonett adapter with ILED-B geometry according CIE 127, spectral data, color temperature, CRI, chromaticity coordinates, etc.
BTS256-LED-DA Compact Bi-Tec measurement device for the measurement of illuminance and luminous flux.

Features: Bajonett adapter with diffusor for the BTS256-LED, +/- 30° cosine corrected field of view, spectral radiant power, color temperature, CRI, chromaticity coordinates, etc.
ISD-21-BTS256-LED System for the luminous flux and light color measurement of individual 2π light emitting diodes up to 63.5mm.

Features: Integrating sphere with 21cm diameter and auxiliary lamp, compact spectral light meter with Bi-Tec sensor for acurate measurement of the luminous flux, spectral radiant power, CCT, CRI, chromaticity coordinates, etc.
ISD-50-BTS256-LED System for the luminous flux and light color measurement of individual 2π light emitting diodes up to 100mm.

Features: Integrating sphere with 50cm diameter and auxiliary lamp, compact spectral light meter with Bi-Tec sensor for acurate measurement of the luminous flux, spectral radiant power, CCT, CRI, chromaticity coordinates, etc.
ISD-50HF-BTS256-LED System for the luminous flux measurement of 4π (optional 2π and 4π) light fixtures inside a sphere.

Features: Integrating sphere with 50cm hemispherical shell for opening and closing and auxiliary lamps. Light meter with Bi-Technology sensor for acurate measurement of luminous flux, spectral radiant power, CCT, CRI, chromaticity coordinates, etc.
ISD-100HF-BTS256-LED System for the luminous flux measurement of 2π and 4π light fixtures inside a sphere.

Features: Integrating sphere with a 1000 mm diameter, hemispherical shell for opening and closing, auxiliary lamp. Light meter for acurate measurement of luminous flux, spectral radiant power, CCT, CRI, chromaticity coordinates, User software, etc. Options: quadripole test sockets.
GB-GD-360-RB40-2-BTS256-LED Goniometersystem for the luminous flux and light color measurement of individual 2π light emitting diodes with an adjustable measurement distance up to 2000mm.

Features: Goniometer, compact spectral light meter with Bi-Tec sensor for acurate measurement of the luminous flux, spectral radiant power, CCT, CRI, chromaticity coordinates, IES, EULUMDAT, etc.
S-SDK-BTS256 Software Development Kit for BTS256 variants
Article-Nr Modell Description Request / Compare
Product
15297817 BTS256-LED

Measurement device, BTS256-LED-CA10 cone adapter, USB cable, hard-top casing, operation manual, S-BTS256 software, calibration certificate.

Re-calibration
15300226 K-BTS256-LED-I

Recalibration of the BTS256-LED Tester. Only possible with the 10mm cone adapter

Software
15298218 S-SDK-BTS256

Software Development Kit for the implementation of the BTS256 or variants into custom made software

Accessories
Note: BTS256-LED-X

The use of cone adapters with measurement ports larger or smaller than 10 mm increases the measurement uncertainty and is only recommendable in applications where the standard units are not suitable.

15297945 BTS256-LED-CA5

Cone adapter with 5 mm measurement port

15298947 BTS256-LED-CA6

Cone adapter with 6 mm measurement port

15298948 BTS256-LED-CA7

Cone adapter with 7 mm measurement port

15298949 BTS256-LED-CA8

Cone adapter with 8 mm measurement port

15298950 BTS256-LED-CA9

Cone adapter with 9 mm measurement port

15297954 BTS256-LED-CA10

Cone adapter with 10 mm measurement port

15298951 BTS256-LED-CA11

Cone adapter with 11 mm measurement port

15298952 BTS256-LED-CA12

Cone adapter with 12 mm measurement port

15298953 BTS256-LED-CA13

Cone adapter with 13 mm measurement port

15298954 BTS256-LED-CA14

Cone adapter with 14 mm measurement port

Further Information

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