Browse Prior Art Database

A Method and Apparatus for Measuring Micron and Sub-Micron Beam Sizes

IP.com Disclosure Number: IPCOM000037849D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bellar, RJ: AUTHOR [+4]

Abstract

This publication describes a method for measuring and characterizing micron and sub-micron optical beam sizes used for, but not limited to, optical recording of data on various types of optical media.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 83% of the total text.

Page 1 of 1

A Method and Apparatus for Measuring Micron and Sub-Micron Beam Sizes

This publication describes a method for measuring and characterizing micron and sub-micron optical beam sizes used for, but not limited to, optical recording of data on various types of optical media.

Miscellaneous techniques have been used in the past to measure beams of this nature. All have depended upon either stepping a target between a detector and the beam to be measured or spinning a target. In both cases, the accuracy of the measurement depends upon determining the speed of the target in the latter case, or the steady positioning of the target in the former case. The detector signal is representative of the beam size if the velocity or the position of the target is accurately known.

The subject method uses a displacement signal from a HeNe laser positioning system to accurately trigger a D/A converter every 5.27 nanometers of target travel. The D/A converter samples the output of the detector which is then stored in computer memory. Various computer programs collect, perform noise reduction and analyze this data.

By utilizing a very accurate XYZ stage, a repeatability of ten nanometers has been routinely achieved. In addition, diffraction-limited spot sizes of a 780 nanometer laser have been measured through various Z axis positioning, giving a through focus curve characterization (see figure).

Added spot and beam characteristics can be realized with this method. As an example, focus a...