The BTS256-LED is a high-quality light meter for measurement of the luminous flux, luminous spectrum and luminous color of LEDs in the visible spectral range. 

 

BiTec light sensor for complex light measurement 

One of the characteristic properties of the mobile light meter is its BiTec light sensor. This combines the characteristic properties of a silicon photodiode with those of a low-noise CMOS diode array. The BiTec sensor guarantees precise photometric, spectral-radiometric and colorimetric measurement values over a large dynamic range through mutual correction of the measurement signals of both sensors.

Silicon photodiode detector, fast and linear 

When taking into account the dynamic range, linearity and speed, silicon photodiodes have always been and are still the ultimate radiation detectors. A silicon photodiode is therefore incorporated in the BiTec light sensor of the BTS256-LED Tester. Its precise matching to the photometric V(λ) CIE responsivity is also ideal for LEDs due to the integration of the diode array’s spectral measurement data. 

Diode array detector for spectral measurement data 

The low-noise CMOS diode array of the BiTec Light sensor provides precise measurement data required for the luminous spectrum. This data is then used for calculation of the color values as well as for optimization of the photometric responsivity. 

Optimized Signal to Noise Ratio 

The noise signal of a diode array detector has significant influence on the Signal to Noise Ratio and thereby affects the quality of the measurement signal. A remote controlled shutter in the BiTec light sensor enables online compensation of the dark signals that are dependent on the temperature and integration time. 

Integrated integrating sphere 

The integrating sphere with conical shaped entrance port of the LED Tester enables explicit capture of all the irradiated light from the LEDs independent of their emission characteristics. The cone adapter is placed over the LED for measurement of assembled LEDs. The auxiliary lamp of the BTS256-LED Tester helps compensate for any measurement errors that might result from light absorption on the test LED. 

Integrating sphere with protective window 

For continuous, long-term use, a protective window protect the integrating sphere against contamination. The cone adapter with bayonet connector can easily be replaced if necessary. 

Use with PC 

The BTS256-LED Tester has a USB 2.0 interface for use of the device with a PC. This enables both data exchange and battery charging. 

User software 

The S-BTS256 software included in the device’s price provides all the necessary functions for the measurements, measurement data display and data transfer. The cutting-edge, flexible desktop concept of the software offers the user an individual constellation of the required measurement values. This can be a full screen filled with lux measurement values or a matrix with both numerical and graphical fields. Each desktop constellation can easily be saved for future use. 

Diverse photometric and colorimetric measurement quantities 

A large span of measurement quantities is necessary for the verification and testing of LEDs. The BTS256-LED Tester offers twelve measurement quantities and thereby meets all the requirements for a modern light meter:

  • Φp luminous flux in lm
  • Φe radiant power in W
  • Φλ spectral radiant power
  • x, y CIE 1931 color coordinates
  • u‘, v‘ CIE 1976 color coordinates
  • CT color temperature
  • Δuv deviation from the blackbody locus
  • λdom dominant wavelength
  • λp peak intensity wavelength
  • λ0,5 spectral half-width
  • Purity color purity
  • CRI Ra and R1 to R15 Color Rendering Index

Software Development Kit 

Gigahertz-Optik offers programmers the S-SDK-BTS256 Software Development Tool. This can be used with LabView from National Instruments, .NET from Microsoft and C/C++. The SDKs simplify integration of the BTS256-LED Tester in an internally developed software. 

Traceable calibration 

The calibration is performed by Gigahertz-Optik’s calibration laboratory for photometric measurands. The calibration is done using calibration standards traceable to national and international standards. Recalibration is recommended after every 12 months. 

Expandable for additional measurement quantities 


The BTS256-LED Tester can be expand for additional measurement quantities using the accessories offered:

  • Diffuser window for measurement of the illuminance of less extensive light sources.
  • External integrating spheres for the luminous flux, luminous spectrum and luminous color of lamps and other luminaires.
  • Goniometer for measurement of the luminous intensity distribution.

For detailed information, please refer to the respective data sheets.

Cone-Adapter for Luminous Flux measurement

Full screen display of the luminous spectrum

S-BTS256 user software with modular desktop setup

CIE 1976 chromaticity table with binning fields

CRI Bar Plot

General
Main features
Short description

Light meter for the luminous flux, spectral radiant power and luminous color

Range of measurement
Typical applications
Calibration
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%

≤3% (f1' a*(sz(λ)) respectively F*(sz(λ)) corrected)

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.
GB-GD-360-RB40 Goniometer for the measurement of 2π sources.

Features: Measurement of the luminous and radiant intensity distribution as well as luminous flux and radiant power from compact spot lamps and light-emitting diodes. Measurement distance 100 mm to 2000 mm. Remote control. Optional Lightmeters, user software, etc.
ISD-21-V01-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-V01-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-V01-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
S-BTS256 Application software for BTS256 variants
Article-Nr Modell Description Notice
Product
15297817 BTS256-LED

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

Calibration
15300226 K-BTS256-LED-I

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

Options
ISD integrating spheres

External integrating spheres with diameters ranging from 21cm to 100cm (data sheet: BTS256-LED with ISD integrating sphere)

GB-GD-360-V01

Goniometer (data sheet: BTS256-LED with GB-GD-360)

Software
15298108 S-BTS256

User software for BTS256 and variants.

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

15297959 BTS256-LED-DA

Diffuser window (BTS256-LED data sheet with BTS256-LED-DA)


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