Standard
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AS ISO 8598.1:2017
[Current]Optics and optical instruments — Focimeters, Part 1: General purpose instruments
Adopts ISO 8598-1:2014 to specify requirements and test methods for general purpose focimeters designed for the measurement of vertex powers, cylinder axis, prismatic power and prism base setting within a restricted area at a specified location of a lens. This excludes instruments that can only measure the whole lens at once.
Published: 07/08/2017
Pages: 27
Table of contents
Cited references
Content history
Table of contents
Header
About this publication
Preface
Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Technical requirements for general purpose focimeters
4.1
4.2
4.3
4.4
4.5
4.6
4.7
5 Metrological requirements
5.1 General
5.2 Reference wavelength
5.3 Performance requirement
5.3.1 Indication error
5.3.2 Axis marker for the optical centre of lens
5.3.3 Axis marker alignment
5.3.4 Adjusting rail
5.3.5 Capability of measuring tinted lenses
5.3.6 Non-symmetric errors for automated focimeters
5.3.6.1 General
5.3.6.2 Non-symmetric error for cylindrical power
5.3.6.3 Non-symmetric error for cylinder axis
5.3.6.4 Non-symmetric prism error
5.3.7 Repeatability for the indication reading of automated focimeters
5.3.8 Centration error for manual focusing focimeters
5.3.9 Astigmatic axis repeatability for low-powered cylindrical lenses with manual focimeters
6 Test procedures
6.1 General
6.2 Checking the indication errors
6.2.1 Checking the indication errors for vertex power
6.2.2 Checking the indication errors for prismatic power
6.3 Checking the axis marker for the optical centre of lens
6.4 Checking the alignment of the axis marker
6.5 Checking the adjusting rail
6.6 Checking the non-symmetric error for automated focimeters
6.6.1 General
6.6.2 Checking the non-symmetric error for cylindrical power
6.6.3 Checking the non-symmetric error for cylinder axis
6.6.4 Checking the non-symmetric prism error
6.7 Checking the repeatability of vertex power measurement for automated focimeters
6.8 Checking for the centration error
6.9 Checking the capability of focimeters to measure tinted lenses
6.10 Checking the astigmatic axis repeatability for low-powered cylinder lens
6.11 Special procedures for eyepiece focimeters
6.11.1 Setting-up procedure
6.11.2 Checking for the absence of parallax
6.12 Criterion for image focusing in manual focusing focimeters
7 Marking
7.1 Reference to ISO 8598-1
7.2 General information to be supplied by the manufacturer
7.3 Additional information to be supplied by the manufacturer
Annex A
A.1 General
A.2 Terms and definitions
A.3 Preparatory to a measurement
A.3.1 General
A.3.2 Choice of reference lenses and lens support
A.3.3 Measurement condition
A.3.3.1
A.3.3.2
A.3.3.3
A.3.4 Special procedure for manual focusing focimeters
A.3.4.1 Checking for the absence of parallax for eyepiece focimeters
A.3.4.2 Criterion for image focusing
A.4 Calculation of the correction value
A.4.1 Indication error of a focimeter
A.4.2 Correction value for calibrated focimeter
A.4.3 Calculation example
A.4.3.1 Measuring a positive reference lens
A.4.3.2 Measuring a negative reference lens
A.5 Using correction values while measuring lens samples
A.5.1 General
A.5.2 Examples of using correction values
A.5.2.1 Correction for a positive lens
A.5.2.2 Correction for a negative lens
A.6 Verification period
Annex B
B.1 General
B.2 Terms and definitions
B.3 Evaluation of uncertainty of measurement
B.3.1 General
B.3.2 Evaluating standard uncertainty
B.3.2.1 Model the measurement
B.3.2.2 Standard uncertainty for each component
B.3.2.2.1 General
B.3.2.2.2 Uncertainty, u1, of the true value for vertex power, Φ
B.3.2.2.3 Uncertainty, u2, of the indication reading, d, for vertex power, Φ
B.3.2.2.3.1 Type A evaluation
B.3.2.2.3.2 Example of a Type A evaluation
B.3.2.2.3.3 Type B evaluation
B.3.3 Combined standard uncertainty
B.3.4 Expanded uncertainty
B.3.5 Evaluation result
B.4 Applying uncertainty in practice
B.4.1 Example for a negative spectacle lens
B.4.2 Example for a positive spectacle lens
Annex C
C.1 General
C.2 Terms and definitions
C.3 Spherocylindrical-power reference lens
C.4 Reference filter
Annex D
D.1
D.2
Bibliography
Cited references in this standard
[Current]
Optics and optical instruments - Test lenses for calibration of focimeters - Part 1: Reference lenses for focimeters used for measuring spectacle lenses
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