Methods and systems for validating parallelism between internal facets

Abstract

Disclosed herein is a method including: (i) providing a light transmissive sample including nominally parallel internal facets, which are about perpendicular to an external surface of the sample; (ii) providing an optical element having a refractive index about equal to that of the sample and including an external first surface and an external second surface acutely inclined relative thereto; (iii) positioning the second surface of the optical element adjacent to the first surface of the sample; (iv) impinging light beams on the first surface of the optical element, about normally thereto; (v) sensing light beams, which exit out of the sample following passage of the impinging light beams via the optical element, transmission thereof into the sample, reflection once off the internal facets, and exit out of the sample; and (vi) based on the sensed data, computing a deviation from parallelism between the internal facets.