Methods and systems are provided for using optical interferometry in the context of material modification processes such as surgical laser or welding applications. An imaging optical source that produces imaging light. A feedback controller controls at least one processing parameter of the material modification process based on an interferometry output generated using the imaging light. A method of processing interferograms is provided based on homodyne filtering. A method of generating a record of a material modification process using an interferometry output is provided.

An interferometer system for measuring the displacement of a location of a test surface includes a reflective beamsplitter having a through-hole through which light enters into and exits from a reference arm and having a second through-hole through which a portion of light from the measurement arm of the interferometer passes through the beamsplitter and is incident on a position sensing device (PSD). The output of the PSD is then used as an indicator of the amount and direction of tilt of the surface under test so that systemic errors of the interferometer induced by the tilt of the test surface can be determined and removed from the displacement measurement.

A system for wafer pairing for wafer-to-wafer bonding may include a wafer shape metrology sub-system and controller. The controller may receive the shape measurements for a set of top wafers and bottom wafers and then sort the set of top wafers and the bottom wafers into wafer groups based on the shape measurements. The controller may tag each top and bottom wafer with a wafer group number and determine wafer pairs from selected wafer groups. The controller may calculate the bow difference for each wafer pair of the set of wafer pairs and sort the set of wafer pairs into wafer pair groups based on intervals of bow difference. The controller may associate each wafer pair group with a corresponding reference recipe and direct a bonder to bond the wafer pairs in a selected wafer pair group according to a corresponding reference recipe associated with the selected wafer pair group.

A low coherence interferometer imaging system includes an imaging engine generating a reference beam and an object beam, a first beam splitting element, reference ends, a sample end, and optical imaging modules arranged at the sample end. The first beam splitting element is disposed on an optical path of the reference beam and generates sub-reference beams after the reference beam passes through the first beam splitting element. The reflected sub-reference beams and the reflected object beam form interference signals through the imaging engine. The imaging engine generates images after analyzing the interference signals. One optical imaging module is first arranged at the sample end; the remaining optical imaging modules are sequentially arranged at the sample end in an optical-path series manner so that the images exhibit distinct imaging fields of view before and after the optical imaging module is arranged and when arrangement parameters of the imaging engine remain unchanged.