54A0059_V1.1_EN / LeddarSteer DBSD Evaluation Board
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User Guide
45 | 50
There are a total of three types of transition to qualify with the DBSD:
1.
Transition time for one of the first 7 cells to go from being relaxed (low voltage) to active (high voltage)
2.
Transition time for one of the first 7 cells to go from being active (high voltage) to relaxing (low voltage)
3.
Transition time for the 8
th
cell to go from acting as a
𝜆
4
waveplate to a
3𝜆
4
waveplate
The first type of transition is called a “fast transition” and occurs when all of the first 7 cells stay relax or
become active. As such, there is no relaxation time to be considered.
The second type of transition is ca
lled a “slow transition” and occurs when at least one of the first 7 cells
needs to be relaxed so it can transition from a high voltage to low voltage. This relaxation time is always
slower than the fast transition.
The third type of transition is more so related to the change of polarization of the output beam. In fact, to
evaluate this transition time, called
“
polarization transition
,”
place a polarizer between the emitted beam and
the power meter. Then, simply calculate the rise time (from 10% to 90% transmitted power) once the
calibrated voltage of the 8
th
cell is switched.
Table 29: Expected rise time from 10% to 90% for each transition type
T
fast
(µs)
T
slow
(µs)
T
polarization
(µs)
50 - 100
≤
750
≤2500 (at 60
°C)
The tested transition should give results in the vicinity of those shown in Table 29.
