PLS Series LEDs are the fastest miniature sub-nanosecond pulsed UV/blue/green/orange LED sources available.
They combine short pulse widths (<500 ps FWHM) with high repetition rates (from single shot up to 40 MHz) in a compact and maintenance free set-up.
Their spectral and timing characteristics are also particularly suitable for biomedical applications, e.g. for the detection of labeled substances as well as naturally fluorescent amino acids like tryptophan or tyrosine.
With peak powers up to 1.5 mW, a combination of interchangeable PLS Series heads satisfies the demand for a compact and affordable excitation source that covers a wide range of wavelengths.
These LED heads can only be driven by the PDL 800-B, PDL 800-D or PDL 828 'Sepia II' driver units.
The most important difference between the pulsed LEDs and pulsed laser diodes is the fact that the emission of the LEDs is divergent, not coherent, not polarised and also non-uniform in its intensity distribution. Depending on the LED used, different beam shapes can be seen ranging from near-round to elliptical. Fibre coupling into single mode or multi mode optical fibres has therefore only low efficiency - a notable exception being large area fibres such as liquid light guides. However, for short range interactions e.g. in a compact time-resolved fluorescence lifetime spectrometer, the LEDs of the PLS Series are very useful excitation sources.
The PLS heads are supplied with an integrated lens and an internal security circuit to prevent damage for the UV LEDs (PLS 255 to PLS 570) if operated above 10 MHz. The head diameter is 30 mm.
From 10 years of experience with data from several thousand laser diodes, the typical lifetime is found to be >2000 working hours for UV/blue laser heads and LEDs, >6000 working hours for red laser heads. These values relate to conditions where the laser head is driven in an appropriate manner at maximum settings of repetition rate and output power. Working at lower repetition rates and output powers increases the lifetime accordingly.