Orb Optronix has expanded its LED Test and Measurement Services Laboratory, offering complete optical, thermal and electrical characterisation of light emitting diodes.
To deal with the problem of determining the true operational performance of LEDs, Orb Optronix has developed advanced laboratory facilities to accurately measure LEDs' spectral output under tightly controlled thermal conditions over a range of forward drive currents with high precision forward voltage (Vf) monitoring.
‘Historically, the characteridation of light sources has not required this level of control for product development,’ said David Jenkins, Orb’s president. ‘For many applications today, this level of characterisation is absolutely necessary - particularly in LED display technology, medical devices, and LED lighting applications. We have new and expanded facilities for automated parametric measurement and characterisation of LEDs. We employ two types of temperature control for different purposes. Ambient air temperature control is used primarily for characterising product or subsystem level performance, while thermoelectric cooler (TEC) temperature control is used primarily for component level characterisation of discrete LEDs and LED arrays. Our facilities offer complete thermal, electrical, and optical characterisation.’
The spectral radiant flux of an LED is a function of many variables including temperature, current, and forward voltage, each as a function of time. This leads to additional relevant variables when you include frequency and duty cycle for pulse width modulated current (PWM) control.
High power LED manufacturers are currently specifying optical output of their LEDs under short single current pulse conditions. Today’s high power LED specification sheets generally assume that the junction temperature is equal to the ambient air temperature of 25°C. Although these tests are easily repeatable, they are not particularly useful to engineers designing LEDs into illumination and display products. The decrease of luminous flux and shift in wavelength as temperature rises is highly variable and depends on the properties of LEDs. NIST’s Optical Technology Division (OTD) is conducting research to address this important issue and recommends LED characterisation be performed under TEC Control. This information is necessary when designing robust LED-based products with specific desired light output and lifetime characteristics.
LED integrators can now accurately and completely characterise LEDs using Orb’s services to solve these complex product development challenges.
