ISO 19012-1:2013

Microscopes - Designation of microscope objectives - Part 1: Flatness of field/Plan

ISO 19012-1:2013 specifies the use of the marking "Plan" on microscope objectives, and defines the diameter of the sharp region of the primary image of a flat object surface. ISO 19012-1:2013 applies to visual observation using the combination of objective lens, tube lens and eyepiece, as specified by the manufacturer. This marking is consistent with ISO 8578.

Microscopes — Désignation des objectifs de microscope — Partie 1: Planéité du champ/Plan

General Information

• Status: Published
• Publication Date: 13-May-2013
• ICS: 37.020 - Optical equipment
• Technical Committee: ISO/TC 172/SC 5 - Microscopes and endoscopes
• Drafting Committee: ISO/TC 172/SC 5/WG 9 - Optical performance of microscope components
• Current Stage: 9093 - International Standard confirmed
• Start Date: 13-Mar-2024
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 19012-1:2011 - Microscopes - Designation of microscope objectives - Part 1: Flatness of field/Plan
• Effective Date: 10-Mar-2012

Overview

ISO 19012-1:2013 - "Microscopes - Designation of microscope objectives - Part 1: Flatness of field/Plan" defines how the “Plan” designation is applied to microscope objectives and how to quantify the flat region of the primary image of a flat object surface. The standard applies to visual observation using the objective, tube lens and eyepiece combination as specified by the manufacturer, and is consistent with ISO 8578.

Key topics and technical requirements

• Plan marking and indication
  • Objectives branded Plan (or described as “flat field”) must also display the objective field number (OFN) on the objective body (exemption for lenses sold before 2014).
  • OFN examples: 18, 19, 20 … 30 etc. (e.g., OFN25).
• Definition of Plan objectives
  • A Plan objective must have a plan field ratio (PFR) ≥ 0.85, where PFR = PFN / OFN.
• Plan field number (PFN)
  • PFN specifies the diameter (mm) of the sharp region of the primary image of a flat object surface.
  • PFN is determined as the maximum field of view of the primary image that meets flatness tolerances defined by the standard.
• Flatness criteria
  • The standard uses the distances of the tangential and sagittal image surfaces from the image plane to compute average image surface distance (Δ) and astigmatic difference. Both |Δ| and astigmatic difference must be ≤ the depth-of-focus δ calculated by Berek’s formula.
  • Determination assumes a 10× eyepiece for the visual assessment.
• Optical aberrations
  • The Plan designation addresses field flatness and does not imply correction for other aberrations (see ISO 10934-1). The 2013 edition explicitly includes Petzval curvature in its considerations.
• Berek’s formula and depth of field
  • Annex A provides Berek’s formula to compute δ (depth of focus/field) from parameters such as total visual magnification, numerical aperture (NA) and wavelength.

Applications and who uses this standard

• Microscope manufacturers - labeling objectives and specifying field performance.
• Optical designers - designing and verifying flat-field objectives (Plan).
• Quality assurance and calibration labs - testing PFN/PFR and compliance.
• Purchasing/specification engineers and lab managers - selecting objectives for photomicrography, pathology, materials inspection or any application requiring a uniformly sharp field.
• Standards bodies and educators - harmonizing terminology and training on objective designation.

Related standards

• ISO 8578 - marking of objectives and eyepieces
• ISO 10934-1 - vocabulary for microscopy (light microscopy)
• ISO 19012-2 - Chromatic correction (companion part)

Keywords: ISO 19012-1:2013, Plan objectives, flatness of field, microscope objectives, plan field number (PFN), objective field number (OFN), plan field ratio (PFR), Berek’s formula, depth of field, Petzval curvature, astigmatism.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 19012-1
Third edition
2013-05-15
Microscopes — Designation of
microscope objectives —
Part 1:
Flatness of field/Plan
Microscopes — Désignation des objectifs de microscope —
Partie 1: Planéité du champ/Plan
Reference number
©
ISO 2013
© ISO 2013
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ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 2
4.1 Indication . 2
4.2 Definition of plan objectives . 2
4.3 Determination of plan field number . 2
Annex A (informative) Depth of field in object space calculated by Berek’s formula .4
Bibliography . 7
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of
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Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
The committee responsible for this document is ISO/TC 172, Optics and photonics, Subcommittee SC 5,
Microscopes and endoscopes.
This third edition cancels and replaces the second edition (ISO 19012-1:2011) by the addition of
“Petzval curvature”.
ISO 19012 consists of the following parts, under the general title Microscopes — Designation of
microscope objectives:
— Part 1: Flatness of field/Plan
— Part 2: Chromatic correction
The following parts are under preparation:
— Part 3: Spectral transmittance
iv © ISO 2013 – All rights reserved

INTERNATIONAL STANDARD ISO 19012-1:2013(E)
Microscopes — Designation of microscope objectives —
Part 1:
Flatness of field/Plan
1 Scope
This part of ISO 19012 specifies the use of the marking “Plan” on microscope objectives, and defines the
diameter of the sharp region of the primary image of a flat object surface. This part of ISO 19012 applies
to visual observation using the combination of objective lens, tube lens and eyepiece, as specified by the
manufacturer.
This marking is consistent with ISO 8578.
NOTE The flatness of the image field does not imply any degree of correction for other aberrations
(ISO 10934-1).
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 10934-1, Optics and optical instruments — Vocabulary for microscopy — Part 1: Light microscopy
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10934-1 and the following apply.
3.1
tangential structured object
object containing short lines perpendicular to the
...