The PDL 828 is a completely computer controlled multichannel picosecond pulsed diode laser driver connected to the PC via USB. The Sepia II provides maximum flexibility for multiple wavelength applications and drives any combination of up to 8 laser heads or LED heads in a user defined sequence. The PDL 828 can be used with the picosecond pulsed laser diode heads from 375 to 1550 nm (LDH-Series, LDH-P-FA-530) as well as with the sub-nanosecond pulsed LEDs from 255 to 600 nm (PLS-Series). A special multi-chip laser module (SML 828) is also available and is targeted at application that require more power than available from a standard LDH Series laser head.

The whole system is configured and controlled through a dedicated Windows control software - no manual settings are necessary. Last settings are saved inside the Sepia II to allow standalone operation which is very useful for measurement automation. A DLL is also available and allows to access all functions of the Sepia II from custom programs.

The system consists of a mainframe with power supply, an oscillator module with three selectable master frequencies of 80, 64 and 50 MHz and up to eight laser driver modules. The repetition rate is derived from the selected master frequency or from an external trigger source by division through any integer value between 1 and 256. A synchronization signal is provided with each pulse and its position on the time axis can be varied within the limits of the pulse period in steps of the size of the master oscillators period. With this unique feature no external delays are needed anymore for TCSPC at low repetition frequencies. At the start of a burst, this signal can also be inhibited (masked out) for a user defined number of pulses.

The eight output channels of the oscillator module can be configured in a most flexible way: Bursts can be defined for each channel up to a length of 16.7 million pulses. In that way arbitrary burst patterns can be generated, which is extremely useful for e.g. multicolor excitation schemes. Multiple channels can also be combined for parallel operation and a marker signal can be generated for each burst sequence to signal the end of a sequence. The system works in a rotary scheme, which means that the programmed sequence of one channel must be completed before the next channel is activated.

Each laser head is connected to a dedicated laser module which allows to control the output power of the laser head. The laser modules can be triggered by the oscillator module or any other external NIM-signal. For an operation independent from the oscillator module each laser module also has its own internal oscillator, which provides six fixed frequencies from 2.5 to 80 MHz. A synchronization output is also provided with each pulse. The laser module also allows cw operation with the newest generation of laser heads (LDH-D Series).