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Re: Automatic entry of density values

Jorge Gasteazoro

19:13 13 Feb 04

UV-VIS spectrophotometer as a tranmission densitometer?

Jon J.

17:36 13 Oct 03

I am trying figure out how to utilize a UV-VIS spectrophotometer as a transmission densitometer to carry out BTZS testing and calibration. I have purchased the book and am reading it with interest.

In brief, this instrument is capable of very accurate measurements of the absorbance of light from 190nm to 1190 nm. It can determine absorbance at discrete wavelengths (e.g. 210nm and 289 nm) or can scan over any given range (e.g. 190-1190nm). My understanding of a transmission densitometer is that it will measure the absorbance of light but uses 'white light'.

For both instruments the absorbance should be calculated similarly. Namely, absorbance = recieved light/transmitted light.

My question is what wavelengths of light could I monitor to determine film densities that will approximate the information garnered from a simple transmission densitometer. Should I simply monitor the visible spectrum (~ 390nm - 780nm)? Or would it be more appropriate to just look at red, yellow and blue wavelengths?

The data readout is a graph of wavelength (x-axis) vs. absorbance (y-axis). I could calibrate by using a step tablet of know densities and then integrate the area under the abs. vs. wavelength plot over the entire visible spectrum.

Am I making this too complicated? I don't have a spot meter nor densitometer.

Of course reading paper (reflectance) densitometer is another matter.

Any thoughts? Suggestions? Thanks in advance,

Jon J.