A first optical axis of a first optical component is caused to be at a first angle with respect to a first precision surface of the first optical component. A second optical axis of a second optical component is aligned to be at a second angle to a second flat surface of the second optical component. The second angle is equal to or derived from the first angle. The first and second flat surfaces are caused to directly face each other to allow only sliding motion between the first and second flat surfaces. The sliding motion is performed between the first and second flat surfaces until the first and second optical axes are sufficiently collinear.