BTS256-EF

Development from Lux Meter to Spectral Light Meter

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. The European Commission's Ecodesign Regulation now requires SVM and Pst measurements and even specifies limit values for them.

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. See technical article about the measurement of TLA (Temporal Light Artefacts).

BTS256-EF – High-Quality, 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.

*One of its unique features is the from Gigahertz-Optik developed innovative BiTec sensor that consists of a V(lambda) filtered Si photodiode and a spectroradiometer unit. This makes it extremely linear, stable, and fast and is therefore a guarantee for higher measurement accuracy which is not accompanied by any disadvantages. Both sensors can be used independently and the mutual correction of the sensors is advantageous for accuracy, speed and versatility.

Thus, the meter supports all the requirements of a modern spectral light meter allowing also high accuracy for LED measurements: 

• 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 portable hand-held use

A High Accuracy Light Flicker Meter suited also for LEDs

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

• Percent Flicker (IEEE Std 1789-2015, IES: RP-16-10, CIE:TN-006, CIE:TN-012)
• Flicker Index (IEEE Std 1789-2015, IES: RP-16-10, CIE:TN-006, CIE:TN-012)
• FFT Frequency component analysis
• P_st Short term flicker severity (CIE:TN-006, CIE:TN-012, IEC TR 61547)
• Stroboscopic Visibility Measure, SVM (CIE:TN-006, CIE:TN-012, IEC TR 63158)
• M_p ASSIST Flicker perception metric
• Joint Appendix JA10

The measurands Percent Flicker, Flicker Index and the FFT frequency component analysis are available in the BTS256-EF's stand-alone configuration. All other measurands are only accessible when the BTS256-EF is remote-controlled via the included S-BTS256 software. The same is true for the Wi-Fi version of the BTS256-EF. There is a limitation though: The measurands PstLM and SVM require a very high data throughput that can only be realized via a USB cable. These are not available when the BTS256-EF WiFi is connected via Wi-Fi.

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.

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 Flicker and General Lighting Meter

One essential quality feature of photometric devices is their precise and traceable calibration. The BTS256-EF is calibrated by Gigahertz-Optik’s ISO 17025 highes quality 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.

DALI Alliance Tests IEC 62386-209

Enables CCT measurements to be fully automated in the official DALI Alliance tests in accordance with IEC 62386-209 (colour control gear).

Further Options for the Spectral Light Meter BTS256-EF

• Software development kit for integration of the device in the user’s own software
• In combination with software tool S-T-Flicker and the programmable AC Source LPS-CH-500 Gigahertz-Optik GmbH offers a functional extension of the BTS256-EF for an test system according to the IEC TR 61547-1:2017 Equipment for general lighting purposes - EMC immunity requirements - Part 1: An objective light flicker and fluctuation immunity test method.