BTS256-LED Plus Concept

Manufacturers of LED based products ranging from general lighting to niche products such as bicycle lamps and headlamps require various measurement capabilities to ensure product performance and quality.

For example, the tolerance classifications in LED binning often exceed those permitted by the application or do not match the end use operating conditions thereby requiring device testing and selection.  Therefore, manufacturers benefit from versatile, cost effective and accurate light meters that meet the differing measurement requirements of product development, goods-in inspection and testing of single LEDs, measurement of assembled LED arrays and single LEDs, as well as quality control of the final products.

The Plus concept for flexible use of the BTS256-LED

The BTS256-LED Plus concept is based on the BTS256-LED, a compact spectral light meter that can be used to measure the luminous flux, spectrum, color, and color rendering index of LEDs. One key feature of the BTS256-LED is its conical measurement port that makes it possible to perform measurements of assembled single LEDs even within array formats.

With the optional accessories, the range of functions of the BTS256-LED device can be easily enhanced to suit different applications. One distinguishing feature of this spectroradiometer is its precision bayonet socket for attaching accessory equipment. This eliminates the need for connecting light guides which avoids the common reproducibility problems experienced when connecting and disconnecting light guides and thereby maintains traceable calibration.

Optional components of the BTS256-LED Plus concept

The BTS256-LED-DA diffuser window can be used to extend the measurement functions of the BTS256-LED, making it possible to measure the illuminance. It provides the required cosine correction over a ± 30^o field of view and is therefore only recommended for measurement of directional lamps specifications. For the illuminance measurement of extended light sources Gigahertz-Optik GmbH offers the MSC15 and BTS256-EF light meters. BTS256-LED-DA specifications.

The BTS256-LED-IB illuminance adapter is designed for measurement of the averaged LED intensity according to CIE 127 Condition B. When combined with the internal integrating sphere of the BTS256-LED, this adapter provides extremely high uniformity across the 1 cm² measurement area specified within the CIE 127. BTS256-LED-IB specifications.

The BTS256-LED may also be used with external integrating spheres from the ISD series  enabling 4-Pi luminous flux measurements in spheres up to 100cm diameter and 2-Pi measurements with ports up to 254 mm. The 2-Pi measurement port of the ISD-21 has a maximum diameter of 63.5 mm, whereas the maximum diameter of the ISD-50 is 127 mm. The fully opening ISD-50HF and ISD-100HF integrating spheres are well-suited for measurement of 4-Pi lamps thanks to their height-adjustable sample holders at the center of the sphere. These spheres can also be fitted with a 2-Pi measurement port (127 mm or 254 mm diameter) that remains closed when not in use. All spheres are equipped with an auxiliary lamp. The ISD-100HFT sphere rotates in its stand conveniently allowing measurements to be made taking into account the thermal effects in different operating orientations of the devices under test. External ISD-Series spheres also increase the maximum level of luminous flux that can be measured by the BTS256-LED.

The GB-GD-360-R40-2 goniometer can be used to enhance the BTS256-LED in order to perform illuminance distribution measurements of 2π lamps.

Calibration of the BTS256-LED

One essential quality feature of photometric devices is their precise and traceable calibration. Calibration of the BTS256-LED with the optional accessories is done 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 calibration description can be found in the datasheets of the BTS256-LED with the corresponding accessories.