Chapter 28 - Physical Optics: Interference and Diffraction - Problems and Conceptual Exercises - Page 1004: 16

$1.16\mu m$

We know that $d=\frac{m\lambda}{sin\theta}$ We plug in the known values to obtain: $d=\frac{(1)(670\times 10^{-9}m)}{sin(35^{\circ})}$ $d=\frac{670\times 10^{-9}m}{0.5735}$ $d=1.16\times 10^{-9}m$ $d=1.16\mu m$