---
publication_id: "OT-2026-000000119"
title: "Apparatus and methods for verifying alignment between a shadow ring and a substrate"
published_at: "2026-09-15T19:02:30.537874Z"
canonical_url: "https://opentechnical.org/p/OT-2026-000000119"
categories:
  - "sensors-controls-machine-vision/position-and-presence-sensing"
keywords:
  - "g01b5/14"
  - "b05c21/005"
  - "b25j9/1692"
---

# Apparatus and methods for verifying alignment between a shadow ring and a substrate

## Abstract

Methods and apparatus for verifying alignment between an opaque shadow ring and a substrate are provided. In some embodiments, the apparatus includes a tool comprising: a transparent ring having an inner edge defining a central opening and an outer edge and having a top side and a bottom side; a gauge mark on or in the transparent ring spaced between the inner edge and the outer edge, the gauge mark extending around the inner edge; and a pin extending from the bottom side of the transparent ring and located between the gauge mark and the outer edge.