  The proof test and debugging of the multi-pulsed electron accelerator,
Dragon-2,requires a thorough comprehension of the quality of the beams. This
puts forward a rigid requirement on the measurement system that it should have
the ability that not only differentiates the three pulses on the whole but also
tells the details of each pulse.In the measurements, beam energy is converted
by a target to the Optical Transition Radiation (OTR) light, the information
carried by which provides a good approach to measure beam profile and
divergence simultaneously. Combining with this characteristic of OTR light, the
concept of dual-imaging method is adopted in the design of optical imaging
system. To avoid interference of the system optical parameters with one
another, the original system is separated into two parts by functions, one for
beam profile measurements and the other for divergence measurements.
Correspondingly a splitter is interposed immediately after the OTR target which
splits the light into two parts in perpendicular directions, one part forming a
beam spot, and the remaining becoming polarized through a polarizer and imaged
by an OTR lens and forming a beam divergence pattern. Again the use of
splitters helps the light beam enter different framing camera for different
use.With a time resolution of 2ns, the system can provide 8 frames of beam
details within any one of the three pulses,at the same time as acquiring the
quality of the three pulses on the whole.
