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BTS256-EF

With the BTS256-EF, Gigahertz-Optik GmbH, a renowned measuring device manufacturer, offers a universal measuring device for the determination of all relevant light parameters in general lighting. Combined with a programmable AC source, the BTS256-EF becomes a comprehensive flicker test system for lamps and luminaires including voltage fluctuation immunity tests IEC TR 61547-1:2017.

Description

Traditional lux meters are increasingly being replaced by spectral light meters such as the MSC15. However, the lighting industry also needs high accuracy spectral light meters that can handle more complex measurements. These include measurement of pulse width modulated light and the ability to measure both internal and external illumination, determination of thermal transient behavior of lamps, and so on. The primary criterion that such meters must always meet is the quality of their photometric features. Additional electronic features may improve usability and display quality, but they cannot compensate for substandard measurement results.

Manufacturers of lamps and luminaires for general lighting purposes must consider light flicker when qualifying product safety in terms of EMC immunity requirements. In addition to the influence of mains voltage fluctuations, flicker effects caused by the lamp and the luminaire itself must be taken into account.

With the BTS256-EF, Gigahertz-Optik GmbH, a renowned measuring device manufacturer, offers a universal measuring device for the determination of all relevant light parameters in general lighting. Combined with a programmable AC source, the BTS256-EF becomes a comprehensive flicker test system for lamps and luminaires including voltage fluctuation immunity tests IEC TR 61547-1:2017.


BTS256-EF – Highquality, spectral light and color measurement meter

The BTS256-EF is a high-quality measuring device for photometric and colorimetric measurement of general lighting products and conditions. A special feature of the meter is a Bi-Tec sensor. This consists of a fast photodiode and a CMOS array detector. Thus, the meter supports all the requirements of a modern light meter:

  • Cosine field of view illuminance measurement for accurate evaluation of extended illumination (class B DIN 5032 part 7 or AA according to JIS C 1609-1:2006)
  • Flicker measurement
  • Spectral measurement technology, required for LED light, color, color rendering, color effects
  • Photodiode for synchronization to pulse width modulated light and flicker measurement
  • alpha-opic illuminance and irradiance measurement (CIE S 026:2018)
  • Compact and robust design for mobile use

 BTS256-EF – Flicker meter

In its function as a light-flicker meter, the BTS256-EF supports all current flicker measurements:

  • Percent Flicker (IEEE Std 1789-2015, IES: RP-16-10, CIE: TN-006)
  • Flicker Index (IEEE Std 1789-2015, IES: RP-16-10, CIE: TN-006)
  • FFT Frequency component analysis
  • Pst Short term flicker severity (CIE: TN-006, IEC TR 61547)
  • Stroboscopic Visibility Measure, SVM (CIE: TN-006, IEC TR 63158)
  • Mp ASSIST Flicker perception metric
  • Joint Appendix JA10

In addition, the BTS256-EF allows flicker tests according to IEC TR 61547 when operated in combination with power supply LPS-CH-500. These tests aim to probe flicker stability when light sources are operated in an AC circuit under the influence of disturbance signals.


BTS256-EF – Meter for photosynthetically active radiation (PAR) in plant growth

LED grow lights need to be measured in terms of the Photosynthetically Active Radiation (PAR) they produce. This function is supported by the BTS256-EF. The Photosynthetic Photon Flux Density (PPFD) in µmol/(m²*s) can be measured which is a measure of the total number of photons within the PAR wavelength range that reach a surface each second per square meter area. Furthermore, the daylight integral (DLI) can be displayed which represents the total amount of photosynthetically active radiation received by a plant in the course of a day.


Calibration of the BTS256-EF

One essential quality feature of photometric devices is their precise and traceable calibration. The BTS256-EF is calibrated by Gigahertz-Optik’s calibration laboratory that was accredited by DAkkS (D-K-15047-01-00) for the spectral responsivity and spectral irradiance according to ISO/IEC 17025. The calibration also included the corresponding accessory components. Every device is delivered with its respective calibration certificate.

Specifications

General
Short description Spectroradiometer for the illuminance (photopic, scotopic, melanopic), PAR, spectrum, light color, color rendering index, and flicker
Main features Mobile measurement device, BiTec sensor with a V-lambda photodiode and low stray light CMOS spectroradiometer with a 10 nm optical bandwidth and additional optical bandwidth correction (CIE214), remote-controlled offset shutter, precise cosine-corrected field of view, data  logger, automatic PWM synchronization, flicker measurement of Pst, SVM, Flicker Index, etc.
Measurement range 1 lx to 199,000 lx, 360 nm to 830 nm, flicker frequency between 0.25 Hz and 40 kHz
typical applications Precise spectral light meter for the lighting industry
Calibration Factory calibration, traceable to international standards
Product
Sensor class B DIN 5032 part 7 or AA according to JIS C 1609-1:2006
class A DIN 5032 part 7 for f1’ and f4, or general precision class according to JIS C 1609-1:2006
class L DIN 5032 part 7 for U response, IR response, f3, f6 and f7
Sensor Bi-Technology sensor with a photometric broadband detector and a array spectrometer. Integrated aperture for automatic dark signal adjustment.
Input optics Diffuser window with 20mm diameter, cosine corrected field of view, f2 Error ≤ 3%
Filter Spectral responsivity with fine CIE photometric matching. Online correction of the photometric matching through spectral measurement data (spectral missmatch factor correction)
Flicker Measurands: Percent flicker (IES:RP-16-10, CIE:TN-006), flicker index (IES:RP-16-10, CIE:TN-006), flicker frequency, fast fourier transformation (FFT), Pst  short-term flicker severity Pst (CIE:TN-006, IEC TR 61547), stroboscopic effect visibility measure SVM (CIE:TN-006, IEC TR 63158), Mp ASSIST, joint appendix JA10.

The BTS256-EF has a limited internal memory and can thus only access the following frequency range when used as a handheld meter (without a PC):

Measurement Time (Sensor) Measurement Time (Flicker) Sampling Rate Upper Cut-Off Frequency Lower Cut-Off Frequency Frequency uncertainty at acceptable S/N ratio FFT frequency resolution
50 ms 41.0 ms 20 µs 5 kHz 60 Hz 1%+-0.5 Hz 25 Hz
100 ms 81.9 ms 40 µs 5 kHz 30 Hz 1%+-0.5 Hz 12.5 Hz
200 ms 163.8 ms 80 µs 2.5 kHz 15 Hz 1%+-0.5 Hz 6.3 Hz
500 ms 327.7 ms 160 µs 1.2 kHz 8 Hz 1%+-0.5 Hz 3.2 Hz
1000 ms 655.4 ms 320 µs 0.6 kHz 4 Hz 1%+-0.5 Hz 1.6 Hz
3000 ms 2620 ms 1280 µs 150 Hz 1 Hz 1%+-0.1 Hz 0.4 Hz
6000 ms 5240 ms 2560 µs 75 Hz 0.5 Hz 1%+-0.05 Hz 0.2 Hz
12000 ms 10486 ms 5120 µs 33 Hz 0.25 Hz 1%+-0.02 Hz 0.1 Hz

The measurement range extends to the following range when the BTS256-EF is used in combination with a PC and the S-BTS256 or S-SDK-BTS256 software:

Measurement Time (Sensor) Measurement Time (Flicker) Sampling Rate Upper Cut-Off Frequency Lower Cut-Off Frequency Frequency uncertainty at acceptable S/N ratio FFT frequency resolution
5 ms

to

180000 ms (3 min)

5 ms

to

180000 ms

25 µs min. (40kHz) 5 kHz 2.5/meas. time 1 % ± 0.5 Hz 1/meas. time
Spectral Detector
Chip CMOS diode-array
spectral range (360 – 830) nm
Optical Bandwidth 10 nm, mathematical optical bandwidth correction according to CIE 214 can be automatically applied
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.
typical measurement time 199,999 lx ≤ 5ms (white light)

100 lx ≤ 1s (white light)

Color measurement range spectral (1 – 199,999) lx
Scotopic Scotopic measurement range spectral (1 – 199,999) lx
Calibration uncertainty of scotopic Illuminance +/-2.2%
Peak wavelength +/- 1nm
Dominant wavelength +/- 1nm
Repeatability Δx and Δy +/- 0.0001 (Standard illuminant type A)

+/- 0.0002 (LED)

Δy Δx uncertainty +/- 0.002 (Standard illuminant type A)

+/- 0.005 (typ. LED)

CCT Measurement range (1700 – 17000) K
ΔCCT +/- 50K (standard illuminant type A)

+/- 4% (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)

(typical value, measured 100 nm to the left of the peak of the LEDs)

Calibration uncertainty Spectral irradiance

(360 – 399) nm ± 5,5 %
(400 – 479) nm  ± 4 %
(480 – 779) nm ± 3,8%
(780 – 830) nm ± 4,3 %

Spectral irradiance responsivity (360 – 830) nm

Integral Detector
Calibration uncertainty Illuminance ± 2.2%
f1′ (spectral mismatch) ≤6% (uncorrected)

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

max. illuminance ≥199,999 lx
Noise equivalent illuminance ≤ 0.01lx
ADC 12Bit
Measurement time (0.1 – 6000) ms
temperature range The measured values of the diode are corrected by means of an internal temperature sensor.
Graphs
f2 (directional response/cosine error) f2 BTS256 E
spectral responsivity BTS256 EF Responsivity2
Miscellaneous
Microprocessor 16Bit, 25ns instruction cycle time
Power Supply 5VDC, 450mA per USB
Interface USB 2.0 (Type B USB)

Option WiFi: WiFi 2,4 GHz (external antenna, range > 100m)

temperature range Operation: +10°C bis +30°C

Storage: -10°C bis +50°C

Housing Splashproof IP54
Transport case 333mm x 280mm x 70mm, 650g
Dimensions 159mm x 85mm x 45mm (Length x Width x Height)
Weight 500 g

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