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 |
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| 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 |
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| Measurement range | Luminous flux: 10 mlm - 1100 lm, spectral range: 360 nm - 830 nm, bandwidth: 5 nm with optical bandwidth correction according to CIE 214 |
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| typical applications | Goods-in inspection of individual LEDs, quality assurance of assembled LEDs in production processes, Research and development testing. |
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| Calibration | For diffuse emitting and narrow beam LEDs. Factory calibration. Traceable to international calibration standards. |
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| Product | |||||||
| Calibration uncertainty | ± 5 % for luminous flux
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| Sensor | Bi-Technology sensor with a photometric broadband detector and a array spectrometer. Integrated aperture for automatic dark signal adjustment. |
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| Input optics | Integrating sphere with synthetic ODM98 coating and protective window at the sphere port. Cone adapter coated with ODP97 for radiation absorption. 10 mm diameter measurement port. LED auxiliary lamp. |
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| Spectral Detector | |||||||
| Chip | CMOS diode array |
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| spectral range | (360 - 830) nm |
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| Optical Bandwidth | 5 nm |
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| Data Resolution | 1 nm |
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| Integration Time | (5.2 - 30000) ms |
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| Shutter | Automatic aperture for dark signal measurements with the same integration time as that of light measurements. Aperture delay = 100ms . |
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| typical measurement time | 1100 lm ≤ 5ms (white light) 10 mlm ≤ 30s (white light) |
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| Peak wavelength | ± 0.5 nm |
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| Dominant wavelength | ± 1 nm |
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| Repeatability Δx and Δy | ± 0.0001 (Standard illuminant type A) ± 0.0002 (LED) |
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| Δy Δx uncertainty | ± 0.002 (Standard illuminant type A) ± 0.005 (typ. LED) |
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| CCT Measurement range | (1700 - 17000) K |
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| ΔCCT | ± 50K (standard illuminant type A) ± 3% (depending on the LED spectrum) |
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| CRI (color rendering index) | Ra and R1 to R15 |
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| Stray Light | 6E-4 (Blue LED) 6E-4 (Green LED) 6E-4 (Red LED) 1E-3 (White LED) |
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| Integral Detector | |||||||
| max. luminous flux | 70000 lm |
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| Filter | Spectral responsivity with fine CIE photometric matching. Online correction of the photometric matching through spectral measurement data (spectral missmatch factor correction). |
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| f1' (spectral mismatch) | ≤ 6 % (uncorrected) ≤ 1.5 % (f1' a*(sz(λ)) respectively F*(sz(λ)) corrected by spectral data, done automatically by BTS technology) |
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| ADC | 12Bit |
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| Measurement time | (0.1 - 6000) ms |
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| Noise equivalent luminous flux | 0.05 mlm |
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| Graphs | |||||||
| spectral responsivity |
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| Miscellaneous | |||||||
| Microprocessor | 16Bit, 25ns instruction cycle time |
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| Power Supply | 5VDC to 7VDC, 250mA peak during capacitor charging of the auxiliary lamp |
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| Interface | USB 2.0 (Type B USB port) |
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| temperature range | Operation: (10 to 30) °C Storage: (-10 to 50) °C |
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| Dimensions | 160 mm x 85 mm x 60 mm (Length x Width x Height) |
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| Weight | 500 g |
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| Transport case | Plastic hard-top casing, 333 mm x 280 mm x 70 mm, 650g |
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| Option: 210mm Integrating Sphere (UMBB-210) | |||||||
| Luminous flux measurement range (integral measurement) | (0.35 - 35000) lm |
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| Sphere diameter | 210 mm |
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| Calibration | Luminous flux: ± 5% |
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| Option: 500mm Integrating Sphere (UMBB-500) | |||||||
| Luminous flux measurement range (integral measurement) | (1.2 - 120000) lm |
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| Sphere diameter | 500 mm |
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| Calibration | Luminous flux: ± 5% |
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| Option: 1000mm Integrating Sphere (UMTB-1000-HFT) | |||||||
| Luminous flux measurement range (integral measurement) | (4 - 400000) lm |
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| Sphere diameter | 1000 mm |
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| Calibration | Luminous flux: ± 5% |
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| Option: Irradiance (DA) | |||||||
| Measurement range | Illuminance: (0.2 - 25000) lx |
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| Calibration | ± 2.2 % |
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| Option: Goniometer (GB-GD-360-RB40) | |||||||
| Luminous intensity measurement range (integral measurement) | (2E-1 - 2E8) cd ; by 1m measurement distance |
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| Calibration | Luminous intensity: ± 4 % |
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| Type | Description | File-Type | Download |
|---|---|---|---|
| Datasheet | BTS256-LED | ||
| Dimensions | BTS256-LED dimensions | ||
| Brochure | Light measurement solutions for general and specialized lighting |
| 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. |
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| 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. |
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| 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. |
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| 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. |
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| 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. |
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| 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. |
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| 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. |
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| S-SDK-BTS256 |  |
Software Development Kit for BTS256 variants. |
