Details on an IHL File's Constructions
has four outputs: +X Scan, -X Scan, +Y Scan, -Y Scan (there is no Z Scan because it is summed into the
other four scan outputs).
I.2. Scan Heads
The scan head icon represents the scan head and includes connections for the scanning piezo elements
as well as the other inputs such as bias voltage and a dither piezo in a non-contact AFM, as well as the
scan head outputs such as the bias voltage in an STM and the normal and lateral force signals in an
AFM.
The piezo sensitivities for the scan head are entered in the scan head icon as well as the labels for the
other inputs, such as bias and tunnel current. Connecting the tunnel current pin on an STM scan head to
the input of a preamplifier will propagate the tunnel current label through the preamplifier and ADC to the
R9 system. The inputs and outputs of microscope icon must be connected to the correct input/output
icons in hardware space for the microscope's properties to correctly propagate to the R9 system.
I.3. Preamplifiers
In the case of an STM, the only output pin on a scan head icon is the tunnel current pin. This pin must
connect to a preamplifier (current to voltage converter) before it can be connected to an input channel on
the R9 controller. When one of RHK’s preamplifiers is used, such as the IVP-200 or IVP-300, pre-
configured icons are available in the External Hardware drawer. These icons have their gains pre-
defined so there are no parameters that need to be set.
RHK preamplifiers are connected to the R9 Controller through the IVP-R9 Bias-Preamp Interface
Module. The IVP-R9 adapts the single ended output of the preamplifiers to the differential input circuit of
the R9 Controller. In addition, the IVP-R9 converts the differential output of the R9 drive output to a single
ended signal for the bias voltage. The IVP-R9 therefore has both inputs and outputs for the tunnel current
as well as for the bias voltage. When the IVP-R9 is connected to an ADC input on the R9 Controller, the
ADC’s input selector is automatically switched to the differential input setting and cannot be changed to
look for current on the BNC inputs.
Important
The RHK-supplied cable between the IVP-R9 and the R9 Controller is wired to supply the
bias voltage from Channel 1 Drive and the amplified tunnel current signal to the differential
input channel of Channel 2 Input.
I.4. Input Channels
The output of the STM preamplifier connects to the differential input of the Channel 2 Input. RHK has
standardized on Channel 2 Input as the input channel for the Tunnel Current in an STM. Although the
Channel 1 Input could also be used, it is easier to support customers when their IHL files are similar to
the standard RHK configurations. Channel 2 Input is the standard that is used for the Normal Force
signal in AFM.
I.5. Lock-in Amplifiers
Once the data has been digitized, it flows through Lock-in Channel 1. The Lock-in can operate as either
a simple low pass filter or as a complete lock-in amplifier to demodulate signals such as for dI/dV
spectroscopy, depending on the user's requirements. The Signal output pin of the Lock-in (labeled
Current in the tool tip) is connected to the Signal pin of a Measure Item, which will send the current
channel to the PC over the Ethernet connection. The Signal output of the lock-in is also used as the input
for the PI Feedback loop. A lock-in amplifier must be connected between Input Channels 1 and 2 and
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