---
title: Wedge Lens | Edge Thickness Difference (ETD) | Optimax Tools & Charts
description: Learn about wedge lens control and edge thickness difference (ETD) for precision optics, measured in linear or angular units per ISO 10110-6 standards.
---

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## Wedge Lens

**CONTROLS: **Location of once center of curvature relative to some other item.  It may be related to another center of curvature, a plane in space, or a physical datum.

**RELATED TERMS:**  Edge Thickness Difference (ETD), Edge Runout (ERO), Wedge, Mechanical Wedge, Total Indicated Runout (TIR), Beam Deviation

**UNITS:** Linear units or angular units

**SPECIFICATIONS MUST CONTAIN:** Relationship between a center of curvature and the reference.

**OPTIMAX PREFERRED SPECIFICATION:** ETD

**REASONS:** Directly measured on the machine or with little specialized equipment

**MANUFACTURING STANDARDS:** ISO-10110-6

###### [CLICK HERE TO DOWNLOAD PDF](https://online.fliphtml5.com/yujsl/tmhr/#p=1) OF THE MANUFACTURING TOLERANCE CHART

![wedge lens](https://go.optimaxsi.com/hs-fs/hubfs/wedge-lens-final-3-300x239-1.png?width=300&name=wedge-lens-final-3-300x239-1.png)

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### Learn from the Experts

###### Find out more by downloading our technical note on Centration

**Specifying And Measuring Spherical Surface Irregularity**

Define surface irregularity for spherical surfaces, offer information on measurement methods for testing surface irregularities, and some specification guidelines.

[Learn More](https://go.optimaxsi.com/predicting-stress-cemented-doublets)

[![Lens Tolerance Attributes](https://go.optimaxsi.com/hs-fs/hubfs/Lens-Tolerance-Attributes.png?width=300&name=Lens-Tolerance-Attributes.png)

Optimax - Optics Tolerance Attributes

Optimax, America's largest prototype optics manufacturer, specializes in fast, cost-effective production of precision optical components, including aspheres, cylinders, prisms, and spheres up to 300mm in diameter. With lean practices, in-house coating capabilities, and a focus on small volumes and quick delivery, watch our Optics Tolerance Attributes Video to learn more.

](https://www.optimaxsi.com/manufacturing-tolerance-chart/wedge-lens#)

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