How to Measure MTF and other Properties of Lenses Optikos Corporation 107 Audubon Rd Bldg 3 Wakefield, MA 01880 USA (617) 354-7557 www.optikos.com e-mail
[email protected] July 16, 1999 © Optikos Corporation, 1999 All Rights Reserved Rev. 2.0 #4-04-001 1 2 Introduction With the growing role played by optical devices in measurement, communication, and photonics, there is a clear need for characterizing optical components. A basic and useful parameter, especially for imaging systems, is the Modulation Transfer Function, or MTF. Over the past few decades new instruments, including the laser interferometer, the CCD Camera, and the Computer have revolutionized the measurement and calculation of the MTF. This has made what was once a tedious and involved process into virtually an instantaneous measurement. This booklet is designed to provide insight into the theory and practice of measuring the Modulation Transfer Function and related quantities. While a booklet of this size cannot begin to address all the intricacies and subtleties of testing, it is intended to provide a foundation for understanding, and to introduce the reader to the fundamentals of testing. Various tests and test techniques are described in detail and in concept. Four articles by Optikos staff have been adapted for this booklet: 1. “Why Measure MTF?” identifies the many reasons for the popularity of MTF as a measured quantity and describes the relationship between MTF measurement and other technologies. 2. “Geometric Lens Measurement” is an article that summarizes the field of geometric lens measurement (non-interferometric measurement), and the recent advances which have brought new attention to traditional testing.