Engineering Note: HR4000/USB4000 Shutter Mode Performance In Hardware Trigger Mode

The HR4000 and USB4000 Spectrometers utilize the Toshiba TCD1304 CCD Detector. When operating a USB4000/HR4000 Spectrometer with this detector in External Hardware Trigger mode, you will find some subtle differences between spectra obtained in Normal versus External Hardware Trigger mode. This is due to the differences in the timing signals between the two operating modes. Specifically when operating in External Hardware Trigger mode, the Toshiba TCD1304 detector is being operated in Shutter mode. This is done to continuously clear the detector while waiting for the trigger signal. With this approach, all of the key performance specifications are maintained (e.g., Signal-to-Noise, RMS noise, Baseline Stability, etc).

As with all new features, there are tradeoffs and limitations that exist; the TCD1304 Shutter mode operation is no different; there are limitations that must be realized in it operation. These limitations are outlined herein