What is the LWS efficiency in chop-nod mode?
In imaging mode the efficiency can approach 50%; in spectroscopy mode it is closer to 25%. The reason for this is that the data acquisition system forces us to discard at least one frame during each chopper transition. For imaging, the frame times are short (10 millisec or more) and the losses are small. For spectroscopy, frame times must be increased in order to reach the background-noise-limited regime (100-400 millisec) and hence the losses are much more significant. We are working on a fix, but it involves very low-level reprogramming of the electronics and will take some time to complete.
