ISO 14490-5:2005

Optics and optical instruments — Test methods for telescopic systems — Part 5: Test methods for transmittance

ISO 14490-5:2005 specifies the test methods for the determination of the transmittance of telescopic systems and observational telescopic instruments.

Optique et instruments d'optique — Méthodes d'essai pour systèmes télescopiques — Partie 5: Méthodes d'essai du facteur de transmission

General Information

• Status: Withdrawn
• Publication Date: 24-Oct-2005
• Withdrawal Date: 24-Oct-2005
• ICS: 37.020 - Optical equipment
• Technical Committee: ISO/TC 172/SC 4 - Telescopic systems
• Drafting Committee: ISO/TC 172/SC 4 - Telescopic systems
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 26-Jul-2017

Relations

• Revised: ISO 14490-5:2017 - Optics and photonics — Test methods for telescopic systems — Part 5: Test methods for transmittance
• Effective Date: 02-Jan-2016
• Amended By: ISO 14490-5:2005/Amd 1:2015 - Optics and optical instruments — Test methods for telescopic systems — Part 5: Test methods for transmittance — Amendment 1
• Effective Date: 08-Jan-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14490-5
First edition
2005-10-15

Optics and optical instruments — Test
methods for telescopic systems —
Part 5:
Test methods for transmittance
Optique et instruments d'optique — Méthodes d'essai pour systèmes
télescopiques —
Partie 5: Méthodes d'essai du facteur de transmission




Reference number
ISO 14490-5:2005(E)
©
ISO 2005

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ISO 14490-5:2005(E)
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ii © ISO 2005 – All rights reserved

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ISO 14490-5:2005(E)
Contents Page
Foreword. iv
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Principle.1
5 Test arrangement.2
5.1 General.2
5.2 Source of radiation and condenser .2
5.3 Monochromator or set of filters .2
5.4 Collimator .3
5.5 Aperture stop .3
5.6 Specimen mounting.3
5.7 Veiling glare stop.3
5.8 Integrating sphere.3
5.9 Radiation detector .3
6 Procedure .3
6.1 Preparation of the test assembly .3
6.2 Determination of the measurement values .4
6.3 Further test methods.4
7 Precision of the measurement .4
8 Presentation of the results .4
9 Analysis .4
9.1 Effective transmittance for photopic vision.4
9.2 Effective transmittance for scotopic vision .5
10 Test report .5
Annex A (informative) Calibration procedure for the photoreceiver/measuring instrument .6
Annex B (informative) Trichromatic coefficients and colour contribution index .9
Bibliography .12

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ISO 14490-5:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards 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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14490-5 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 4,
Telescopic systems.
ISO 14490 consists of the following parts, under the general title Optics and optical instruments — Test
methods for telescopic systems:
⎯ Part 1: Test methods for basic characteristics
⎯ Part 2: Test methods for binocular systems
⎯ Part 3: Test methods for telescopic sights
⎯ Part 4: Test methods for astronomical telescopes
⎯ Part 5: Test methods for transmittance
⎯ Part 6: Test methods for veiling glare index
⎯ Part 7: Test methods for limit of resolution
The following part is under preparation:
⎯ Part 8: Test methods for night-vision devices

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INTERNATIONAL STANDARD ISO 14490-5:2005(E)

Optics and optical instruments — Test methods for telescopic
systems —
Part 5:
Test methods for transmittance
1 Scope
This part of ISO 14490 specifies the test methods for the determination of the transmittance of telescopic
systems and observational telescopic instruments.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/CIE 10526, CIE standard illuminants for colorimetry
ISO 14132-1:2002, Optics and optical instruments — Vocabulary for telescopic systems — Part 1: General
terms and alphabetical indexes of terms in ISO 14132
ISO 14490-1:2005, Optics and optical instruments — Test methods for telescopic systems — Part 1: Test
methods for basic characteristics
CIE Publication 18.2:1983, The basis of physical photometry
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14132-1 apply.
4 Principle
To determine the spectral transmittance τ(λ), the flux of radiation in a limited bundle of rays will be measured
before entering Φ (λ) and after passing Φ (λ) through the optical system. The transmittance results from the
0 p
Equation (1):
Φλ()
p
τλ()= (1)
Φλ()
0
During the spectral measurement, the emergent light of the radiation source will be limited to a small
wavelength band by means of a monochromator or a set of filters.
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ISO 14490-5:2005(E)
5 Test arrangement
5.1 General
The measuring device consists of radiation source (optionally with condenser), monochromator or set of
filters, collimator lens, aperture stop, specimen mounting, veiling glare stop, integrating sphere, radiation
detector and measuring and evaluation unit (signal processing).
See Figure 1.

Key
1 radiation source 5 collimator lens 9 integrating sphere
2 condenser 6 aperture stop 10 detector
3 monochromator 7 test specimen 11 baffle
4 selectable diaphragm as field stop 8 veiling glare stop 12 measurement and evaluation unit
Figure 1 — Test arrangement (schematic)
5.2 Source of radiation and condenser
The radiation source shall emit a continuous flux of radiation in the specified wavelength range. The variation
of flux during the measurement of a pair of values shall be less than 1 %. The condenser adapts the radiation
source to the optical measurement path.
5.3 Monochromator or set of filters
Grating or prism monochromators can be used to select the wavelength. The smallest adjustable wavelength
distance shall be less than 2 % of the dominant wavelength of the respective measurement.
The necessary spectral bandwidth depends on the sample. It shall be ensured that a steep alteration of the
transmission curve is detected correctly. Thus the bandwidth shall be smaller than the distance in the
wavelength, at which the transmittance is changed by 4 %. This condition cannot always be satisfied because
of measuring and energy reasons or because the time/cost effort is not adequate. In these cases, a maximum
bandwidth of 4 % of the wavelength is allowable. A bandwidth of less than 2 % of the wavelength is necessary
if the colour rendition indices are to be calculated.
Instead of a monochromator a set of filters can be used. They are especially useful with flat-shaped
transmittance curves. The number of measuring points shall allow for a definite curve fitting. Measurement
with spectral filters can be applied as well if only single measuring points are required.
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ISO 14490-5:2005(E)
5.4 Collimator
The collimator may contain a refracting lens or mirror. The collimator has to be adjusted to the aligned
components in such a way that full and uniform illumination of the following aperture stop is assured. The axial
chromatic aberration of a refracting lens shall be less than or equal to 1 % of its focal length in the spectral
range used. An off-axis parabolic mirror or an equivalent system is also suitable as a collimator.
5.5 Aperture stop
The aperture stop should be circular and located close to objective lens of the test specimen if possible. The
diameter should be u 80 % (50 % recommended) of the maximum available aperture of the test specimen.
Auxiliary systems can be used for beam forming to realize these requirements. These systems shall stay in
the ray path during measuring with and without test specimen.
5.6 Specimen mounting
The mounting of the test specimen shall be designed in a way that the test specimen can be adjusted and
held stable.
5.7 Veiling glare stop
A veiling glare stop with a diameter 1,1 times the diameter of the image of the aperture stop is located in the
image plane of the aperture stop, consequently in the exit pupil of the telescope. The veiling glare stop shall
be dull black on both sides. It shall be designed in a way that the veiling glare resulting from the test specimen
and upsetting the measurement result is reduced as far as possible; it shall further be designed in a way that
the necessary radiation for the measurement passes through unobstructed.
5.8 Integrating sphere
The integrating sphere shall be located near the veiling glare stop to ensure that the light passing through the
veiling glare stop will be completely collected by the integrating sphere. The integrating sphere has two
openings, one for the input of the bundle of rays to be measured and one for the detector. Both openings shall
not be located opposite each other. Direct radiation incident on the detector is prevented by baffles. The
surfaces of the two openings together shall not occupy more than 5 % of the internal surface of the sphere.
The diameter of the integrating sphere opening shall exceed the maximum diameter of the image of the
aperture stop (6 in Figu
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