An apparatus for optical sensing of samples includes an optical source, an optical assembly, a sample holder, an objective lens, and a detector. The objective lens collimates light emitted by the sample. Preferably, the optical assembly rotates about an axis, allowing the sensing apparatus to sense results from plural locations on a sample without moving the sample. Moving the sample in a linear direction while rotating the optical assembly allows sensing of an entire sample. Preferably, light from the optical source enters the optical assembly along the axis of rotation. Sensing methods consistent with the invention are also described.