Coaxial distance measurement via folding of triangulation sensor optics path

An apparatus for scribing a nominally flat substrate, the apparatus comprising:

• (a) an optics set for focusing a scribe beam onto the substrate at a scribe position to create a scribe line on the substrate when the substrate and scribe beam are moved with respect to each other;
• (b) a beam focus adjustment mechanism for adjusting the optics set to cause a focal point of the scribe beam to follow contours on the substrate as the substrate moves with respect to the scribe beam during scribing;
• (c) a triangulation-based distance sensor comprising (i) a detection beam source for issuing an incident beam for reflecting off the substrate and (ii) a detector for detecting the position of a reflected beam created when the incident beam reflects off the substrate, wherein the position of the reflected beam on the detector provides an indication of a distance between the triangulation-based distance sensor and the substrate, and wherein the triangulation-based distance sensor is configured such that the incident beam emanates from the detection beam source substantially orthogonal to the scribe beam;
• and
• (d) at least one reflecting element positioned to (i) reflect the incident beam from the triangulation-based distance sensor onto the substrate at a location on or proximate to the scribe position, and (ii) reflect the reflected beam from the substrate onto the detector, such that the triangulation-based distance sensor provides the indication of a distance between the triangulation-based distance sensor and the substrate.

A method for scribing an electrochromic lite having a first side and a second side with an electrochromic device disposed on the first side, the method comprising:

• (a) determining a position of an interface of the first side of the electrochromic lite and the electrochromic device using a triangulation-based distance sensor, the triangulation-based distance sensor oriented such that a first laser beam from a triangulation laser is substantially parallel to the first side of the electrochromic lite, is reflected from the electrochromic lite, and is detected by a detector;
• (b) adjusting a focus lens such that a scribe beam emitted from a scribe laser impinges the second side of the electrochromic lite and is focused at the interface of the first side of the electrochromic lite and the electrochromic device, an appropriate focal distance determined by the position of the interface provided by the triangulation-based distance sensor;
• and
• (c) ablating the electrochromic device from a region of the first side of the electrochromic lite with the scribe beam.

An assembly comprising:

• a triangulation laser;
• a detector;
• a first mirror configured to reflect a first laser beam from the triangulation laser about 90 degrees and onto a surface of a substrate, and to tilt the first laser beam at an angle relative to a line normal to the substrate;
• and
• a second mirror configured to reflect the first laser beam, after it is reflected from the surface of the substrate, about 90 degrees and to the detector;
• wherein the assembly is configured to accommodate a scribe beam from a scribe laser such that the first laser beam strikes the substrate substantially at a focal point of the scribe beam.