1. The problem statement, all variables and given/known data So I'm trying to determine the slit separation of a 2-D grid (as I understanding it, basically a grid with a lot of parallel, equally spaced slits in the x and y directions). I know I have to use some form of the formula d*sin(theta) = m*lambda, and I'm having some trouble deciding which one. I'd appreciate it if someone could clarify if these are correct: d*sin(theta) = m*lambda for constructive interference, double slit d*sin(theta) = (m+0.5)*lambda for destructive interference, double slit b*sin(theta) = m*lambda for destructive interference, single slit b*sin(theta) = (m+0.5)*lambda for destructive interference, single slit where d=slit spacing and b=slit width 2. Relevant equations 3. The attempt at a solution If my equations are right, then I would use the one for constructive interference of a double slit?