Quantum Instruments Cascade Laser Starter Kit - Manual (Page 21)

Starter Kit Instruction Manual Description 20
4.5 QCL pulser switching unit(LDD100)
4.5.1 Description
The switching unit is based on dedicated power
MOS-FETS with up to 30A current compatibilities
and 60V. In addition, the circuit is limited in power
dissipation by the cooling of the unit. During op-
eration, the temperature of the case should not ex-
ceed 60C. While powering usual QC diodes, these
limitations are never reached because the laser has
usually much lower power ratings.
! WARNING !
An important feature of this unit is that
both lines going to the laser are ”HOT”, i.e.
have a postive voltage respective to the case.
this feature should be kept in mind when de-
signing the laser holder. This one should be
insulated and have a low capacitance(< 100pF)
towards the ground.
The QCL pulse switching unit is composed of
the following connectors:
(1) Low impedance connector
(2) Drive cable connector
(3) Monitoring BNC connector
4.5.2 Specifications
Voltage : . . . . . . . . . . . . . . . . . . . . . . max 60 VDC
Current : . . . . . . . . . . . . . . . . . . . . . . max 30 ADC
Repetition rate : . . . . . upto 1MHz, limited by
average current
Rising/falling edge: . . typical 8ns (max 12ns)
Minimum pulse width: . . . . 16ns, typical 20ns
Maximum pulse width: 1µs, limited by power
supply
Support power: . . . . . . . . . . . . given by TPG128
Trigger IN: . . . . . . . . . . . . . . . . . . . . . . . . TTL 50Ω
Propagation delay: . . . . . . typical 35ns <40 ns
Size: . . . . . . . . . . . . . . . . . . . . . 90 x 130 x 50 mm 3
! WARNING !
The connection between the laser and the
QCL pulse switching unit is floating. It must
not be connected with the ground.
1
2
3
connected to + hi High Voltage Pulse on top, Bottom Output
Current control Max 60V
Power supply 12V
Input
LDD 100
Monitor 20 A/V, Z50 Ohm
Fig.9: QCL pulser switching unit front and rear view