A Michelson's interferometer is illuminated by krypton orange light, which has a wavelength of 605.8 nm. The interferometer is adjusted to give circular fringes (i.e. fringes of constant inclination), and the distances between the beam splitter and the two mirrors are adjusted so that the central spot is a maximum of intensity. The difference between these distances is approximately 1.5 mm.
i) Calculate the angular radii of the first three bright fringes. (Answers given: θ = 1.15°, 1.63°, 1.99°)
ii) A crosshair is positioned on the third fringe, and one of the mirrors is moved. During the movement, 500 fringes pass the crosshair. How far was the mirror moved? (Answer: 0.151 mm)