Princeton 4300 User Manual

52 

PI-SCX System Manual 

Version 2.E 

 

52 

This technique is also useful in high light level experiments, where the camera is again 

photon shot-noise limited. Summing multiple pixels in software corresponds to collecting 

more photons, and results in a better S/N ratio in the measurement. 

The output amplifier amplifies the collected charge from the output node and outputs it as 

electrons/count. Although Figure 18 shows an array with a single output node and 

amplifier, some PI-SCX systems are available with dual output nodes and amplifiers (one 

set at each end of the shift register).  If your system has dual output amplifiers, you can 

choose the output amplifier to be used (High Capacity or Low Noise) via WinView/32 or 

WinSpec/32 on the 

tab:  



 

 Provides a spectrometric well capacity that is 

approximately 3 times the well capacity for the Low Noise amplifier selection. 

High Capacity is suitable when you have intense light signals or signals with 

high dynamic range.  



 

 Provides the highest sensitivity performance and is 

suitable when you have weak signals. 

The choice of output amplifier and analog gain setting should be considered 

together for the best signal capture.

 

Note:  A gain control switch is located on the rear of the PI-SCX:1300 camera but has 

been deactivated. However, analog gain is changeable via the WinView/WinSpec 

software (on the 

tab card).  If your camera 

is not designed for analog gain selection, these settings will not be accessible in the 

software.  
Analog gain control (a function of the preamplifier) is used to change the relationship 

between the number of electrons acquired on the CCD and the Analog-to-Digital Units 

(ADUs or counts) generated.  In WinView/32 and WinSpec/32, the analog gain choices 

vary depending on the CCD array and the number of output amplifiers:   



  Single Amplifier:

 Typically, three settings are available: Low 2x, Medium 1x, 

and High 1/2x.  



  Dual Amplifier:

 Typically, three settings are available: Low 2x, Medium 1x, and 

High 1/2x (Low-noise mode) or Low 4x, Medium 2x, and High 1x (High-

capacity mode). 

The analog gain of the detector should generally be set so that the overall noise is ~1 

count RMS. In most instances this will occur with the switch set to Medium. If the array 

is a 1340 × 1300 configured with the low-noise output, Low will probably be a more 

suitable Analog Gain setting. In situations where the A/D range exceeds that of the array, 

it will generally be better to set the Analog Gain to High so that the signal can be spread 

over as much of the A/D range as possible. This is a particularly important consideration 

in absorbance measurements. Users who consistently measure low-level signals may 

wish to select High, which reduces some sources of noise. Users who measure high-level 

signals may wish to select Low to allow digitization of larger signals. Customized values 

of gain can be provided. Contact Princeton Instruments for additional information.