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New instruments for LED characterisation

Instrument Systems is launching a new series of CCD array spectrometers and a current source. Both have been specially designed to assess LEDs

 The CAS 120 series of measuring instruments has been specifically developed for price-sensitive applications in spectral light measurement, such as LED production or quality assurance. Although costs have been reduced, technical innovations deliver even higher levels of reliability.

The CAS 120 is an optical spectrometer which analyses the spectral characteristics of light radiation. Having additional optical probes and absolute calibration turns this type of measurement system into a spectroradiometer.



CAS 120 CCD array spectroradiometer

A Crossed Czerny Turner Spectrograph with back-illuminated CCD detector forms the core of the spectrometer. This means that the CAS 120 guarantees exceptionally low stray light and a very high level of optical precision.

Cost-intensive cooling of the CCD detector with 2048 x 14 pixels was deliberately omitted for the CAS 120. Instead, the temperature of the CCD detector is recorded each time a spectrum is measured, and an innovative algorithm automatically corrects the signal.

The newly developed filter wheel with density filters OD 1 to OD 4 comes without any mechanical position switches and always guarantees exact filter positions. It expands the total dynamic range of the CAS 120 to 8 decades, enabling the measurement of low and high light intensities without manual intervention in the test procedure.

The CAS 120 is equipped with a USB interface and a TTL trigger I/O. The hardware trigger permits synchronisation with other instruments which is essential for exact measurement results during fast production testing.




Examples of data from a CAS 120 spectroradiometer shown on SpecWin Pro analysis software

Instrument Systems supplies a DLL and a LabVIEW driver for use in production environments and at automated measurement stations. SpecWin Pro and SpecWin Light spectral software packages have been developed for a wide range of laboratory applications with functions for analysis and documentation of test results.

The firm is also marketing the LSM 350 4-quadrant source and measurement unit specifically designed to meet the requirements for production testing of LEDs and LED wafers. High test speeds and the multi-channel capability make the LSM 350 an attractive solution for supplying current or voltage to LEDs with low to medium power output.



LSM 350 basic module in bench enclosure

High test speeds and the multichannel capability make the LSM 350 an attractive solution for supplying current or voltage to LEDs with low to medium power output. Combination with high-precision array spectrometers from Instrument Systems creates a complete solution for optical and electrical testing carried out on LEDs.

As a bipolar current and voltage source, the LSM 350 offers all functions necessary for testing LEDs fast. The automatic polarity test feature can be used for single and multi-chip LEDs. Dedicated measurement ranges permit particularly precise testing at low forward currents of 1 μA, and measurement of reverse currents in the nA range.

The modular concept includes an option to measure breakdown voltages up to 40 V. Very short settling times reduce the test cycles by up to 40% compared to those of most standard current sources.

The LSM 350 is fully integrated in the LED Tester. The turnkey system with the high-precision array spectrometers in the CAS 140CT or CAS 120 series allows test routines to be set up with fully automated testing and binning of LEDs and for testing LED wafers. The associated software permits a large number of different functions and evaluation options.



System solution for LED Tester
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