ASTM E1951-01

Standard Guide for Calibrating Reticles and Light Microscope Magnifications

SCOPE
1.1 This guide covers methods for calculating and calibrating microscope magnifications, photographic magnifications, video monitor magnifications, grain size comparison reticles, and other measuring reticles. Reflected light microscopes are used to characterize material microstructures. Many materials engineering decisions may be based on qualitative and quantitative analyses of a microstructure. It is essential that microscope magnifications and reticle dimensions be accurate.  
1.2 The calibration using these methods is only as precise as the measuring devices used. It is recommended that the stage micrometer or scale used in the calibration should be traceable to the National Institute of Standards and Technology (NIST) or a similar organization.  
1.3  This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Dec-2001
• ICS: 37.020 - Optical equipment
• Technical Committee: E04 - Metallography
• Drafting Committee: E04.03 - Light Microscopy

Relations

• Replaces: ASTM E1951-98 - Standard Guide for Calibrating Reticles and Light Microscope Magnifications
• Effective Date: 10-Dec-2001
• Replaced By: ASTM E1951-02 - Standard Guide for Calibrating Reticles and Light Microscope Magnifications
• Effective Date: 10-Apr-2002
• Referred By: ASTM D7416-09(2020) - Standard Practice for Analysis of In-Service Lubricants Using a Particular Five-Part (Dielectric Permittivity, Time-Resolved Dielectric Permittivity with Switching Magnetic Fields, Laser Particle Counter, Microscopic Debris Analysis, and Orbital Viscometer) Integrated Tester
• Effective Date: 10-Dec-2001
• Referred By: ASTM E45-18a - Standard Test Methods for Determining the Inclusion Content of Steel
• Effective Date: 10-Dec-2001
• Referred By: ASTM E883-11(2017) - Standard Guide for Reflected–Light Photomicrography
• Effective Date: 10-Dec-2001
• Referred By: ASTM E1077-14(2021) - Standard Test Methods for Estimating the Depth of Decarburization of Steel Specimens
• Effective Date: 10-Dec-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 1951 – 01
Standard Guide for
1
Calibrating Reticles and Light Microscope Magnifications
This standard is issued under the fixed designation E 1951; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 5. Procedures
1.1 This guide covers methods for calculating and calibrat- 5.1 Nominal Magnification Calculations:
ing microscope magnifications, photographic magnifications, 5.1.1 A calculated magnification, using the manufacturer’s
video monitor magnifications, grain size comparison reticles, supplied ratings, is only an approximation of the true magni-
and other measuring reticles. Reflected light microscopes are fication, since individual optical components may vary from
used to characterize material microstructures. Many materials their marked magnification. For a precise determination of the
engineering decisions may be based on qualitative and quan- magnification observed through an eyepiece, see the procedure
titative analyses of a microstructure. It is essential that micro- describe in 5.5.
scope magnifications and reticle dimensions be accurate. 5.1.2 For a compound microscope, the total magnification
1.2 The calibration using these methods is only as precise as (M ) of an image through the eyepiece is the product of the
t
the measuring devices used. It is recommended that the stage objective lens magnification (M ), the eyepiece magnification
o
micrometer or scale used in the calibration should be traceable (M ), and, if present, a zoom system or other intermediate lens
e
to the National Institute of Standards and Technology (NIST) magnification (M ). An expression for the total magnification is
i
or a similar organization. shown in Eq 1.
1.3 This standard does not purport to address all of the
M 5 M 3 M 3 M (1)
t o e i
safety concerns, if any, associated with its use. It is the
5.1.3 Example 1—For a microscope configured with a 10X
responsibility of the user of this standard to establish appro-
objective, a 10X eyepiece, and a 1.25X intermediate lens, the
priate safety and health practices and determine the applica-
total magnification observed through the eyepiece would be
bility of regulatory limitations prior to use.
calculated as follows.
2. Referenced Documents
M 5 10 10 1.25 5 125 (2)
~ !~ !~ !
t
2.1 ASTM Standards:
5.2 Calibration for Photomicrography Magnifications:
2
E 7 Terminology Relating to Metallography
5.2.1 The magnification of an image can be determined by
2
E 112 Test Methods for Determining Average Grain Size
photographing a calibrated stage micrometer using the desired
optical setup. First, photograph the stage micrometer using the
3. Terminology
desired combination of objective, bellows extension, zoom and
3.1 Definitions—All terms used in this guide are defined in
intermediate lens, and then measure the apparent ruling length
Terminology E 7.
on the photomicrograph. The measurement should be made
consistently from an edge or center of one division to the
4. Significance and Use
corresponding edge or center of another (see Note 1). By
4.1 These methods can be used to determine magnifications
dividing this apparent length of ruling by the known dimension
as viewed through the eyepieces of light microscopes.
of the micrometer, the magnification of the photomicrograph is
4.2 These methods can be used to calibrate microscope
determined (see Fig. 1). The accuracy of the calibration is
magnifications for photography, video systems, and projection
dependent on the accuracy of the calibrated stage micrometer
stations.
and the scale used to measure the apparent length of the
4.3 Reticles may be calibrated as independent articles and as
photographed ruling.
components of a microscope system.
NOTE 1—The choice of using the edge or center of a reticle line
depends on the method of manufacture used to produce the measuring
device. Some devices are calibrated from center to center while others are
1
measured from one edge to another. Consult with the manufacturer to
This guide is under the jurisdiction of ASTM Committee E04 on Metallography
and is the direct responsibility of Subcommittee E04.03 on Light Microscopy. determine which method should be employed.
Current edition approved Dec. 10, 2001. Published January 2002.
Originally published as E1951–98. Last previous edition E1951–98.
2
Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
E 1951
NOTE 1—This schematic shows the procedure used to determine the calibrated mag
...