Weak Central Diffraction Line

whist doing a diffraction grating experiment in class today, we found that the brightest maxima was not always in the centre! this was clear, not just from perception, and only occurred with 300 lines per mm. is there an explanation as to why this happened? we tried it with different gratings and the same thing happened!(my teacher couldn't answer, and told me I was the only one who cared about it :(
- Ellie (age 17)
London, UK

Ellie- This is a great question. Our message for now (sorry to sound like a politician) is that we care too. But we don't yet know the answer. Just a few background questions might help.

 

What type of light did you use? Was the light hitting the grating straight on or at an angle? What sort of grating was it? Is there a chance you could send a little piece of the grating to us to exam? Or a good microscope picture of the grating?

 

Mike W.

(published on 03/01/2016)