Page 34 · 6300 Series
ComboSource
User’s Manual
The
1220B
or
1221B
cables recommended by Arroyo Instruments are shielded
twisted pair, and will provide good modulation performance.
Current (A) Recommend Wire Gauge
1 or less
24 AWG
2
22 AWG
4
20 AWG
Compensating for Voltage Loss
All cables and connectors have a small, but measureable, resistance. When
driving current through them, this resistance causes a voltage loss in the cable,
and if not compensated for, will result in errors in laser or LED voltage
measurement. In many cases, this is not a problem, as highly accurate voltage
measurement ares not required, and the error can be ignored. However, if
accurate voltage measurements are required, the
ComboSource
offers two
methods to compensate for this loss: the
Cable R
setting and four-wire sense.
Cable R
compensation is software only, so it requires no special wiring to
implement. Four-wire sense, on the other hand, does require additional wiring,
but is the most accurate method. Details on both are found below.
Using Remote Voltage Sense
The
ComboSource
supports remote (4-wire type) voltage measurement of the
laser diode, providing a higher accuracy voltage measurement by directly
measuring voltage at the diode itself. While the
Cable R
setting described below
can provide some of the same benefits of remote voltage sense, remote voltage
sense is a superior method, and they differ in a few key ways:
1.
No need to calculate cable resistance
2.
Voltage measurement is accurate even if the cable resistance changes
3.
The hardware safety circuits use the remote voltage, providing for a
greater degree of protection (
Vf Limit
works on the remote voltage at
the laser rather than the local voltage at the connector)
4.
Works in voltage control mode
The diagram below shows conceptually how to wire the laser to the
ComboSource
, using a 4-wire connection:
6300
LDA Voltage Sense
LDA
LDA
LDA Voltage Sense
Содержание ComboSource 6300 Series
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