Array Linearity (low flux)

Looking at a front surface mirror just outside the entrance window (7µm filter, hi-res mode, narrow slit w/decker), we collected a series of frames at varying integration times and biases.  Picking a 32x32 box in a bright area of one order and converting to electrons based on 35 e per DN, we have the following result:

In the plot above we see good linearity up to ~25,000 electrons for high bias, which is about what I'd expect to be a quarter-full well.  To map the onset of debias/non-linearity, we'll need more light than we're getting off the mirror through the 7µm filter.

If we fit a line to the data above at each bias , we get a curve for detector response as a function of applied bias in perfectly arbitrary units:

This curve doesn't show the characteristic 'S' shape of an IBC detector response, but investigating that will have to wait until after the IRTF run.  We're seeing very linear detector performance up to ~25k electrons, and we'll need to repeat the test with more light to characterize the debias curve.