# Tilted screen in Young's double slit experiment

I was wondering what would happened if we titled the screen in Young's double slit experiment (YDSE) by a certain angle say $$\theta$$. What effect would it have on fringe patterns and their intensities on an axis parallel to the plane of the sheet?

I would speculate that there shouldn't be any signification change if $$\theta$$ is small as $$D$$(distance between slit and screen) $$>>$$ $$d$$(distance between the slots). So the path difference of light from the two slots stays the same as before, i.e. $$∆x=d\sin(\alpha)$$, where $$\alpha$$ is the angle subtended by any point on screen at the center of the two slits. So remaining quantities can be derived similarly.

I also know that if $$\theta =90°$$, there would be no interference pattern and if the screen is overhead the two slits we would get circular fringes.

What would happen in this case?

• Your intuition is right. However, the fringe pattern would change a bit away from its center. If you make a drawing and do the trig, you'll see this. Oct 2, 2019 at 13:43

On the assumption that the screen is far away from the two slits and the angles involved are small the fringe separation is $$\Delta x = \frac {\lambda D}{d}$$ where $$\lambda$$ is the wavelength, $$d$$is the slit separation and $$D$$ the two slit to screen distance.
So $$\Delta x \propto D$$. 