Neurotechnology Research Systems
Optogenetic Controller
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6.8
Verifying the output on an oscilloscope
Before connecting the output to an oscilloscope, confirm that the channel is in voltage output mode.
There are two ways to do this. The GUI should say Laser – Voltage and the LED on the end panel
below the text that says I (on) V (off) should be off.
Hint: If the channel is not playing but the voltage is still ~1.25V, the channel is in current mode. In
current mode, the LED is held at a voltage just below the turn-on threshold so that it can be turned
on more quickly when stimulation starts.
The output for the Pattern1_pulse_bursts.txt file that was loaded in LASER – mV mode should look
like the image below. Note that the scaling is 100mV per division and 1 second per division.
6.9
Using Different Scaling Options
The Optogenetic Controller fundamentally outputs either a 0-5V signal to control a laser or a 0-
1100mA signal to directly power an LED. The Radiant software allows patterns to be specified in
voltage or current, but some users may prefer to specify their stimulation pattern in terms of light
output. By inputting the amount of light produced at the maximum current, a linear interpolation is
performed. The software then calculates the amount of current or voltage required to generate any
light output. As an example, if a given LED outputs 10mW of light at 300mA, this information can
be used to calculate how much current is needed to output a desired amount of light of 7mW. This
calculation is transparent to the user.
In order to find the light output at the max current, the entire system should be assembled
(Optogenetic controller – BNC cable – LED module – Optical patch cable – Optical fiber implant).
User Input
Max Current = 300mA
Light = 10mW
User Request
Light = 7mW
Calculates 210mA