signal, background noise, Fiber optic spectrometer SD2000 Ocean Optics, SpectraSuite

Hello,

I have a problem using the following Ocean Optics Instruments/Softwares doing my research:

- Fiber optic spectrometer SD2000

- External USB A/D Converter: ADC 1000-USB, Serial-No.: ADUD0930

- SpectraSuite: Spectrometer Operating Software (Product Version: SpectraSuite, Operation System: Linux version 3.2.0-4-amd64 running on amd64, Java: 1.6.0_01, VM: Java HotSpot(TM) 64-Bit Server VM 1.6.0_01-b06, Vendor: Sun Microsystems Inc.)

The signal seems to be disturbed/varies from prior measurements. Over the last few months my data showed a "background noise" of 20-40 counts throughout a bigger part of the light spectrum.

Since last week instead of the background noise, my data shows the value "0".

The values suddenly changed during one measurement. The problem persists since then.

I fixed all the settings the same way as before: same light intensity, same lamps, same settings in SpectraSuite (integration time: 100ms, scans to average: 5, boxcar width: 2, strobe/lamp enable: no, electric dark correction: no, nonlinearity correction: no, stray light correction: no, external trigger: normal).

The spectrometer is fixed to a light microscope – it is removed and fixed regularly. There has never been a problem.

Does anyone have a clue what might have happened?

I’d be thankful for any hint.

Best regards,

Katrin