Stray Light current

With real data, a more scientifically valid approach would be to correct the nonlinearity from physical theory. In the current case, for example, a scientifically valid approach would be to convert the data to transmission mode, subtract the stray light and reconvert to absorbance the nonlinear wavelengths would have become linear again. There are, of course, several things wrong with this procedure, all of them stemming from the fact that this data was created in a specific way for a specific purpose, not necessarily to be representative of real data ... 

Figure 17. A crossed grating echelle configuration is being evaluated currently for improved stray light rejection in a smaller size package.

It is not strictly valid in current spectrometric measurements because stray light, scattered light and background effects e.g. from solvents and cuvettes) will produce a net signal in the absence of analyte. 

Excess Current Dark Current and Stray Light 346... 

This neglected two effects that may be important stray light and dark current. They are important not just because they affect the real DC current but also because of their possible effect on the noise and uniformity of the output. We will use excess current to mean the current we have been neglecting - the sum of dark current and the current equivalent of the stray light. We are in a position now to describe how to measure this excess current. 

We can express the excess current in terms of the equivalent excess irradiance. In fact, using the methods described here, we have no way to tell how much of that excess is due to dark current and how much is due to stray light - we can only determine their sum. 

Derivation The derivation is a little messy Let /,deai represent the ideal photon current due only to our source. Let 4 represent the excess current - the sum of any dark current and photon current due to stray light - not due to the source we are using ... 

American Petroleum Institute (API), RP 2003. Protection Against Ignitions Arising out of Static Lighting and Stray Currents. Fifth Edition, API, Washington, D.C., 1991. 

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