Ocean Optics NeoFox Engineering Note - Manual (Page 16)

NeoFox Communication Interfaces
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Autogain Enable Uint Enum 101 600
NEOFOX_AUTOGAIN_ENABLE DeviceSetParameter DeviceGetParameter
The Autogain Enable parameter controls whether the NeoFox device will set its gain settings automatically. When
autogain is enabled, the APD voltage, LED drive levels, and gain levels will be optimized automatically. However, it
is recommended that the autogain should be run at the beginning of experiments to set up the device properly and then
disabled during the course of the experiment itself.
Value Description DLL Constant
0 Autogain disabled NEOFOX_AUTOGAIN_DISABLED
1 Autogain enabled NEOFOX_AUTOGAIN_ENABLED
Reference PGA Gain Uint Enum 105 500
NEOFOX_RED_LED_PGA_GAIN DeviceSetParameter DeviceGetParameter
The Reference PGA Gain parameter controls the amount of electronic gain that is applied to the input signal before
analog to digital conversion. This parameter applies only at times when the reference LED is being sampled and not
when the actual response of the chemistry is being sampled.
Value Description DLL Constant
0 1X NEOFOX_GAIN_1X
1 2X NEOFOX_GAIN_2X
2 4X NEOFOX_GAIN_4X
3 8X NEOFOX_GAIN_8X
4 20X NEOFOX_GAIN_20X
5 40X NEOFOX_GAIN_40X
6 80X NEOFOX_GAIN_80X
7 160X NEOFOX_GAIN_160X
Stimulus LED Current Uint 0 143 516
NEOFOX_DAC_LED_CURRENT_BLUE DeviceSetParameter DeviceGetParameter
The Reference LED Current parameter determines the brightness of the reference LED. The value 0 in this parameter
corresponds to the lowest possible intensity and the value 25000 corresponds to the highest possible intensity.
APD Gain
Uint 3500 141 572
NEOFOX_DAC_APD_GAIN DeviceSetParameter DeviceGetParameter
This parameter sets the open loop APD bias voltage gain, with 3500 representing the maximum possible gain and
9251 representing the minimum possible gain. Note that there is an inverse relationship between this parameter and
the actual gain. To effectively use this parameter, the APD Voltage value should be monitored and the open loop gain
should be adjusted as appropriate to achieve the target APD voltage. Users should be careful to constrain values to the
appropriate range (never lower than 3500), as excessive gain levels may result in damage to the APD.
APD Voltage
Uint n/a 17 768
NEOFOX_ADC_APD_VOLTAGE Read-Only DeviceGetParameter
This parameter allows the user to monitor the APD bias voltage. Higher reverse bias voltages on the APD correspond
to higher “optical gain”, or conversion efficiency, from the detector. The tradeoff of higher APD bias voltage is an
increased risk of detector saturation and higher levels of noise. This value is stored in the NeoFox with a fixed point
representation and hence it must be scaled with the following formula in order to correctly deduce the actual APD
voltage.
Floating Point APD Voltage Value (in Volts) = Raw Integer APD Value / 2
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