Trying to build my own spectrophotometer by hand, and now I have two questions about it:
1. I will use a lens and a diffraction grating to create the different wave lengths. I found the math to calculate the strength of the lens (diopter); D = 1/f, and the place of the focal point; 1/f = 1/a + 1/b. But Im note sure I get it. Just want to check if Im right. This is what I think: If I have a diopter of 20, the focal point will be 5 cm from the lens? (1 divided by the diopter is the focal length).
2. The detector will be a mono meter or something like that. So the answer i will get out of me spectrophotometer will be in voltage. How do I calculate this into absorbance?