Equipment
The digital delay generator is similar to a pulse generator in function but the timing resolution is much finer and the delay and width jitter much less.
Some manufacturers, calling their units "digital delay and pulse generators", have added independent amplitude polarity and level control to each of their outputs in addition to both delay and width control. Now each channel provides its own delay, width and amplitude control, with the triggering synchronized to an external source or internal rep rate generator - like a general-purpose pulse generator.
Some delay generators provide precise delays (edges) to trigger devices. Others provides precise delays and widths to also allow a gating function. Some delay generators provide a single channel of timing while others provide multiple channels of timing.
Digital delay generator outputs are typically logic level, but some offer higher voltages to cope with electromagnetic interference environments. For very harsh environments, optical outputs and/or inputs, with fiber optic connectors, are also offered as options by some manufacturers. In general, a delay generator operates in a 50 ohm transmission line environment with the line terminated in its characteristic impedance to minimize reflections and timing ambiguities.
Historically, digital delay generators were single channel devices with delay-only (see DOT reference below). Now, multi-channel units with delay and gate from each channel are the norm. Some allow referencing to other channels and combining the timing of several channels onto one for more complex, multi-triggering applications. Multiple-lasers and detectors can be triggered and gated. (see second reference on "Experimental study of laser ignition of a methane/air mixture by planar laser-induced fluorescence of OH.)" Another example has a channel pumping a laser with a user-selected number of flash lamp pulses. Another channel may be used in Q-switching that laser. A third channel can then be used to trigger and gate a data acquisition or imaging system a distinct time after the laser fires. (see sensorsportal.com reference below)
Pulse selection or pulse picking of a single laser pulse from a stream of laser pulses generated via mode-locking is another useful feature of some delay generators. By using the mode-locked rate as an external clock to the digital delay generator one may adjust a delay and width to select a single pulse and synchronize other events to that single pulse.
Read more about this topic: Digital Delay Generator
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