Optical coherence tomography system for subsurface inspection

An optical coherence tomography system comprising:

• a) a broadband light source that generates broadband light at an output;
• b) a beam splitter that splits the generated broadband light into a reference beam and an illumination beam;
• c) a reference mirror that is positioned in a path of the reference beam, the reference mirror reflecting the reference beam;
• d) illumination optics positioned in a path of the illumination beam and having a transparent region that passes the illumination beam and having a reflective surface with an optical power;
• e) collection optics positioned in a path of the illumination beam and having a transparent region and having a reflective surface with an optical power, the collection optics being configured so that the illumination beam is reflected from the reflective surface of the collection optics to the reflective surface of the illumination optics such that the illumination beam is redirected to a surface of a sample at an angle that results in scattering from within the sample that forms a sample beam propagating normal to a surface of the sample and through the transparent region of collection optics and through the transparent region of the illumination optics;
• f) an interferometric combiner positioned in the path of the sample beam and in the path of the reference beam, the interferometric combiner being configured to interferometrically combine light from the sample beam and the reference beam;
• g) a spectrometer having an input coupled to an output of the interferometric combiner, the spectrometer configured to receive the interferometrically combined light from the sample beam and the reference beam and to generate spectral interferometric information;
• and
• h) a processor having an input coupled to an output of the spectrometer, the processor processing the spectral interferometric information to determine information about the sample.