Optical detection structures, probe systems that include optical detection structures, and related methods

A method of determining when an objective lens of a lens assembly of an optical detection structure is positioned an objective focal length from a substrate surface of a substrate, the method comprising:

• illuminating the substrate surface with a source laser beam by:
• (i) emitting the source laser beam from a transverse fiber surface of an optical fiber;
• (ii) focusing the source laser beam on the substrate surface utilizing the lens assembly;
• (iii) reflecting the source laser beam from the substrate surface as a reflected laser beam;
• (iv) receiving the reflected laser beam with the lens assembly;
• (v) focusing the reflected laser beam on the transverse fiber surface utilizing the lens assembly;
• (vi) receiving the reflected laser beam into the optical fiber via the transverse fiber surface;
• and
• (vii) detecting a detected intensity of the reflected laser beam received into the optical fiber;
• and
• during the illuminating, selectively varying a distance between the objective lens and the substrate surface.

A method of mapping a surface topography of a substrate surface of a substrate, the method comprising:

• providing an intensity relationship that correlates detected intensity to distance between an objective lens and the substrate surface;
• positioning the objective lens an average mapping distance from the substrate surface;
• illuminating the substrate surface via the objective lens and with a source laser beam and reflecting the source laser beam from the substrate surface as a reflected laser beam;
• during the illuminating, moving the objective lens and the substrate surface relative to one another to scan the source laser beam across the substrate surface;
• responsive to the moving, collecting intensity data indicative of a detected intensity of the reflected laser beam as a function of position of the source laser beam on the substrate surface;
• and
• calculating, for each position of the source laser beam on the substrate surface, a relative surface height, wherein the relative surface height is based, at least in part, on the intensity data and the intensity relationship.