oSIST prEN 167:2007
(Main)Personal eye-protection - Optical test methods
Personal eye-protection - Optical test methods
This European Standard specifies optical test methods for eye-protectors, the requirements for which are contained in other ENs.
Persönlicher Augenschutz - Optische Prüfverfahren
Protection individuelle de l'oeil - Méthodes d'essai optiques
1 Domaine d'application
La présente Norme européenne spécifie les méthodes d'essai optiques pour les protecteurs oculaires dont les spécifications sont données dans d'autres EN.
Il est possible d'utiliser d'autres méthodes s’il est démontré qu'elles sont équivalentes.
Les méthodes d'essais optiques ne font pas l’objet de prEN 168.
Les spécifications sont fournies dans le prEN 166.
Une définition des termes employés est donnée dans l’EN 165.
Osebno varovanje oči - Metode optičnih preskusov
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN 167:2007
01-december-2007
2VHEQRYDURYDQMHRþL0HWRGHRSWLþQLKSUHVNXVRY
Personal eye-protection - Optical test methods
Persönlicher Augenschutz - Optische Prüfverfahren
Protection individuelle de l'oeil - Méthodes d'essai optiques
Ta slovenski standard je istoveten z: prEN 167
ICS:
13.340.20 Varovalna oprema za glavo Head protective equipment
oSIST prEN 167:2007 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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EUROPEAN STANDARD
DRAFT
prEN 167
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2007
ICS 13.340.20 Will supersede EN 167:2001
English Version
Personal eye-protection - Optical test methods
Persönlicher Augenschutz - Optische Prüfverfahren
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 85.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language
made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the
same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to
provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 167:2007: E
worldwide for CEN national Members.
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prEN 167:2007 (E)
Contents
page
Foreword.3
1 Scope .4
2 Normative references .4
3 Test for spherical, astigmatic and prismatic refractive powers .4
3.1 Testing unmounted oculars covering one eye .4
3.2 Testing unmounted oculars covering both eyes and mounted oculars (spectacles, goggles
and face-shields).6
4 Light diffusion test.8
4.1 Principle.8
4.2 Test methods.8
5 Assessment of quality of material and surface.14
6 Determination of transmittance.14
7 Determination of variations in luminous transmittance .15
7.1 Unmounted oculars covering one eye .15
7.2 Mounted oculars and unmounted oculars covering both eyes .16
7.3 Method to correct transmittance for variations in thickness of the ocular .17
8 Determination of spectral reflectance in infrared.18
Annex A (normative) Method for measuring spherical and astigmatic refractive powers over small
areas.19
A.1 Principle.19
A.2 Apparatus .19
A.3 Measurements.20
Annex B (informative) Uncertainty of measurement and results interpretation.25
B.1 Test report and uncertainty of measurement .25
Annex C (informative) Significant technical changes between this European Standard and the
previous edition .27
Annex ZA (informative) Clauses of this European Standard addressing essential requirements or other
provisions of EU Directives .28
2
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prEN 167:2007 (E)
Foreword
This document (prEN 167:2007) has been prepared by Technical Committee CEN/TC 85 “Eye protective
equipment”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 167:2001.
This document has been prepared under a mandate given to CEN by the European Commission and the European
Free Trade Association, and supports essential requirements of EC Directive(s).
For relationship with EC Directive(s), see informative Annex ZA, which is an integral part of this document.
Annex C provides details of significant technical changes between this European Standard and the previous
edition:
3
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prEN 167:2007 (E)
1 Scope
This European Standard specifies optical test methods for eye-protectors, the requirements for which are contained
in other ENs.
Alternative methods may be used if shown to be equivalent.
Non-optical test methods are given in prEN 168.
Specifications are given in prEN 166.
A definition of terms is given in EN 165.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text, and the publications are listed hereafter. For
dated references, subsequent amendments to or revisions of any of these publications apply to this European
Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the
publication referred to applies (including amendments).
EN 165, Personal eye-protection — Vocabulary.
prEN 166:2007, Personal eye-protection — Specifications.
prEN 168:2007, Personal eye-protection — Non-optical test methods.
3 Test for spherical, astigmatic and prismatic refractive powers
NOTE The reference methods for assessment of refractive power are contained in 3.1 and 3.2.
If during measurement using the telescope a doubling or other aberration of the image is observed then the ocular
may either be classified as a defective, or subjected to further examination using the method described in annex A.
3.1 Testing unmounted oculars covering one eye
3.1.1 Apparatus
3.1.1.1 Telescope
A telescope with an aperture of nominally 20 mm and a magnification between 10 and 30, fitted with an adjustable
eyepiece incorporating a reticule.
3.1.1.2 Illuminated target
A target, consisting of a black plate incorporating the cut-out pattern shown in Figure 1, behind which is located a
light source of adjustable luminance with a condenser, if necessary, to focus the magnified image of the light
source on the telescope objective.
The large annulus of the target has an outer diameter of (23,0 ± 0,1) mm with an annular aperture of
(0,6 ± 0,1) mm. The small annulus has an inner diameter of (11,0 ± 0,1) mm with an annular aperture of
(0,6 ± 0,1) mm. The central aperture has a diameter of (0,6 ± 0,1) mm. The bars are nominally 20 mm long and
2 mm wide with a nominal 2 mm separation.
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prEN 167:2007 (E)
3.1.1.3 Filter
A filter with its maximum transmittance in the green part of the spectrum may be used to reduce chromatic
aberrations.
3.1.1.4 Calibration lenses
-1 -1 -1
Lenses with positive and negative spherical refractive powers of 0,06 m , 0,12 m and 0,25 m
-1
(tolerance ± 0,01 m ).
3.1.2 Arrangement and calibration of apparatus
The telescope and illuminated target are placed on the same optical axis (4,60 ± 0,02) m apart.
The observer focuses the reticule and the target and aligns the telescope to obtain a clear image of the pattern.
This setting is regarded as the zero point of the focusing scale of the telescope. The telescope shall be aligned so
that the central aperture of the target is imaged on the centre of the cross-line graticule. This setting is regarded as
the zero point of the prism scale.
The focusing adjustment of the telescope is calibrated with the calibration lenses (3.1.1.4) so that a power
-1
of 0,01 m may be measured. Any other equivalent calibration method may be used.
3.1.3 Procedure
Position the ocular in front of the telescope in the as-worn position, or other position as specified by the
manufacturer. If the as-worn position is unknown, or if no position is specified by the manufacturer then the ocular
shall be positioned normal to the telescopic axis and the tests conducted at the geometric centre.
3.1.3.1 Spherical refractive power and astigmatic refractive power
3.1.3.1.1 Oculars without astigmatic refractive power
The telescope is adjusted until the image of the target is clearly focussed. The spherical power of the ocular is then
read from the scale of the telescope.
3.1.3.1.2 Oculars with astigmatic refractive power
The target, or the ocular, is rotated in order to align the principal meridians of the ocular with the bars of the target.
The telescope is focused firstly on one set of bars (measurement D ) and then on the perpendicular bars
1
D + D
1 2
(measurement D ). The spherical power is the mean, the astigmatic refractive power is the absolute
2
2
difference, D − D , of the two measurements.
1 2
NOTE During this process the best focus shall be used across the whole target for each meridian.
3.1.3.2 Prismatic refractive power
The ocular to be tested is placed in front of the telescope, and, if the point of intersection of the lines of the reticule
falls outside the image of the large circle, the prismatic power exceeds 0,25 cm/m. If the point of intersection of the
lines of the reticule falls inside the image of the small circle of the target, the prismatic power is less
than 0,12 cm/m.
5
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prEN 167:2007 (E)
Figure 1 — Telescope target (dimensions are given in 3.1.1.2)
3.2 Testing unmounted oculars covering both eyes and mounted oculars (spectacles, goggles
and face-shields)
3.2.1 Determination of the spherical and astigmatic refractive power
Position the ocular such that it is in an “as-worn” orientation in front of the telescope.
Measurements of spherical and astigmatic powers shall be taken at points corresponding to the maximum and
minimum pupillary distances as specified by the manufacturer using the procedures specified in 3.1.3.1.
3.2.2 Determination of the difference in prismatic refractive power
3.2.2.1 Apparatus
The arrangement of the reference method is shown in Figure 2.
3.2.2.2 Procedure
The diaphragm LB , illuminated by the light source, is adjusted in such a way that it produces an image on the
1
plane B when the eye-protector (P) is not in position. The eye-protector is placed in front of the lens L in the as-
2
worn position so that the axis of the eye-protector is parallel to the optical axis of the test assembly. Adjustable tilt
eye-protectors are positioned with their oculars normal to the optical axis of the test equipment.
Measurements are taken at the two extremes of pupillary distance claimed by the manufacturer. Consequently, the
distance between the two holes in diaphragm LB2 must be adjustable, or a selection of diaphragms must be
available to cater for the range of pupillary distances which need to be accommodated.
Measure the vertical and horizontal distances between the two displaced images arising from the two ocular
regions of the eye-protector.
These distances in centimetres are divided by two to give the horizontal and vertical prismatic differences
in centimetres per metre.
If the light paths which correspond to the two eye regions cross, the prismatic refractive power is `base in' and if the
light paths do not cross, it is `base out'.
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prEN 167:2007 (E)
Dimensions in millimetres (nominal unless toleranced)
Key
L Light source, for example, small filament lamp, laser with wavelength of (600 ± 70) nm, etc.
a
J Interference filter with peak transmittance in the green part of the spectrum (required only if a filament lamp is used as
the light source)
L Lens, focal length between 20 mm and 50 mm
1
LB Diaphragm, diameter of aperture 1 mm nominal
1
P Eye-protector
LB Diaphragm as shown in detail A
2
L Lens, 1 000 mm nominal focal length and 80mm minimum diameter
2
B Image plane
a
As close as possible.
b
X = (pupillary distance)/2 ± 0.5mm
Figure 2 — Arrangement of apparatus for measurement of prismatic difference
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prEN 167:2007 (E)
4 Light diffusion test
4.1 Principle
The luminance (L ) of an illuminated ocular is a measure of its light diffusion and is proportional to the illuminance
s
(E). The proportionality factor is the luminance factor l = L /E, which is expressed in candelas per square metre per
s
2
(cd / m )
lux .
lx
To obtain a factor l* which is independent of the transmittance of the ocular, the luminance factor is divided by the
transmittance τ.
L
*
s
l =
τE
This quantity is known as the reduced luminance factor and is expressed in the same units as the luminance factor.
NOTE Most oculars have diffusion properties which are symmetrical about the optical axis. For these oculars, the mean
value of the reduced luminance factor is measured within an angle limited by the two cones shown in Figure 3. This mean value
depends upon values α and ∆α.
Key
1 Incident light on optical axis
2 Diffused light
3 Ocular
Figure 3 — Diffusion angles
4.2 Test methods
Two test methods are specified which use the same measurement principle. The `basic method' detailed in 4.2.1
may be used for oculars without corrective effect and for all shade numbers. The `simplified method' detailed
in 4.2.2 has to be used for oculars with corrective effect.
The results obtained with the two methods may be considered to be equivalent; whichever method is used the
relative measurement uncertainty for the reduced luminance factor shall not be greater than 25 %.
Measurements of light diffusion shall be taken at the visual centre of the ocular. If the visual centre is not known
then the geometric centre shall be used.
NOTE Visual centre is as defined in prEN 166:2007.
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prEN 167:2007 (E)
4.2.1 Basic method
4.2.1.1 Apparatus
The arrangement is shown in Figure 4.
The spherical concave mirror H forms an image of light L of identical dimensions at diaphragm LB. The spherical
1
concave mirror H forms an image of diaphragm LB in the plane of diaphragms B and B . The achromatic lens A is
3
L R
positioned immediately behind the diaphragm so that a reduced image of the test sample in position P appears on
diffusing screen MS. The image of iris diaphragm IB is formed at the same time as IB .
1 2
The arrangement collects all the light originating from the filter between angles α = 1,5° and α + ∆α = 2° in relation
to the optical axis.
4.2.1.2 Procedure
The ocular is placed in the parallel beam at position P, then diaphragm B is put in place. The flux Φ falling onto
L 1L
the photodetector corresponds to the undiffused light transmitted by the sample. Diaphragm B is then replaced by
L
annular diaphragm B ; flux Φ falling onto the photodetector corresponds to the total diffused light originating from
R 1R
the filter and from the apparatus. The test sample is then placed at position P′. The flux Φ which then falls onto
2R
the photodetector corresponds to the diffused light coming from the apparatus only.
The difference Φ - Φ corresponds to the light diffused by the filter. The mean reduced luminance factor l* for
1R 2R
the solid angle ω is calculated from the preceding fluxes by means of the formula:
1 Φ −Φ
*
1R 2R
l = ⋅
ω Φ
1L
where
Φ , Φ are the luminance fluxes with the annular diaphragm;
1R 2R
Φ is the luminous flux with the circular diaphragm;
1L
ω is the solid angle defined by the annular diaphragm.
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prEN 167:2007 (E)
Key
L High-pressure xenon lamp (for example XB0 150 W or CSX150 W)
H Spherical concave mirror; nominal focal length 150 mm; nominal diameter 40 mm
1
H Spherical concave mirror; nominal focal length 300 mm; nominal diameter 40 mm
2
H Spherical concave mirror; nominal focal length 300 mm; nominal diameter 70 mm
3
A Achromatic lens; nominal focal length 200 mm; nominal diameter 30 mm
U , U Flat mirrors
1 2
B Annular diaphragm; diameter of outer circle (21,0 ± 0,1) mm, diameter of inner circle (15,75 ± 0,10) mm. See note below
R
B Circular diaphragm; diameter of aperture (7,5 ± 0,1) mm
L
M Photomultiplier corrected according to curve V (λ) with diffusing screen
IB Iris-diaphragm to adjust diameter of field of measurement
1
IB Iris-diaphragm to eliminate edge effects from IB
2 1
LB Circular diaphragm, diameter of aperture (1,0 ± 0,1) mm
MS Diffusing screen
P, P′ Positions of test ocular
Figure 4 — Arrangement of apparatus for measurement of light diffusion - basic method
NOTE The diameters of the annular diaphragm circles shall be measured to an uncertainty not exceeding 0,01 mm in order
that the solid angle ω may be determined accurately; any deviation from the nominal diameters shall be taken into account by
calculation.
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prEN 167:2007 (E)
4.2.2 Simplified method
4.2.2.1 Apparatus
The test arrangement is shown in Figure 5.
NOTE The measurement principle is identical to that given in 4.2.1, but the diameter of the measuring zone is smaller
(approximately 2,5 mm) and the test arrangement is simplified.
The beam of the laser (L) is expanded using the two lenses L and L and is directed towards the measuring point
1 2
of the ocular (P). Ocular (P) is positioned in such a way that it can rotate around the axis of the beam.
The deviation of the beam is a function of the prismatic refractive power at the measuring point.
The annular or circular diaphragm, whichever is chosen, is at a distance of (400 ± 2) mm from the centre of the
ocular.
The lens A then produces the image of the centre of the ocular on the photoreceptor S.
The part of the test arrangement, comprising the diaphragms, the lens and the receptor, is designed to rotate about
the vertical axis through the centre of the ocular.
The ocular and the detector part of the apparatus have to pivot in order to compensate for any prismatic refractive
power of the ocular.
NOTE For oculars without corrective effect, it is not necessary, in most cases, for the ocular and the detector part to pivot.
4.2.2.2 Procedure
4.2.2.2.1 Calibration of the apparatus
Set up the apparatus, the essential features of which are shown in Figure 5, without the ocular in place. Put the
annular diaphragm B in place. Rotate the detector part of the apparatus (consisting of a photoreceptor S, a lens A
R
and the annular diaphragm B ) horizontally about P so as to align the light beam from the beam expander
R
(consisting of a lens L with a typical focal length of 10 mm, a lens L with a typical focal length of 30 mm and a
1 2
circular diaphragm B with a pinhole of sufficient size so as to provide a uniform beam) with the cent
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