BS EN 208:1994 download free.Personal eye-protectors used for adjustment work on lasers and laser svstems.
BS EN 208 applies to laser adjustment eye-protectors. These are eye-protectors for use in adjustment work en lasers and laser systems where hazardous radiation occurs in the visible spectral range of 400 nm to 700 nm. Filters specified in this standard reduce this radiation to values defined for lasers of
class 2 ( I mW for CW lasers). BS EN 208 defines the specifications, test methods and marking.
A selection guide is given in Annex B – EN 207 applies to higher power lasers and eye-protectors against laser radiation.
2 Normative references
BS EN 208 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 arc 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.
prEN 166, Personal eye-protection — Specifications.
prEN 167. Personal eye-protection — Optical test methods.
prEN 168. Personal eye-protection — Non-optical test methods.
EN 207, Personal eve-protection — Filters and eve-protectors against laser radiation.
EN 60825. Radiation safety of kiser prod ucts, equipment classification, requirements and user’s guide. ISO/Cl E 10526:1991, CIE standard colorimetric ilium inants.
ISO/C I E 10527:1991, CIE standard colorimetric observers.
3 Requirements
3.1 Spectral transmittance
Table 1 gives the spectral transmittance values of the filters and the frames for the laser wavelength.
3.2 Luminous transmittance
The manufacturer shall indicate in writing any luminous transmittance below 20 %.
NOTE It is recommended that the luminous transmittance of the fllters. reJative to the 0 65 standard illuminant
(see ISO1CIE 10526:1991 and ISO/VIE 10527:19911 should he at least 20%.
3.3 Stability to laser radiation
The filters and the frames shall meet the requirements of 3.1 when exposed to radiation at the laser wavelength and the power and energy densities given in Table 2 for a period of at least 10 a and
for 100 pulses.
No splinters shall become detached from the side of the filter facing the eye under the influence of laser radiation.
The requirements of the national standards apply to laser radiation protection filters with a corrective effect up until such times as corresponding European Standards have been prepared.
3.5 Quality of material and surface
3.5.1 Material and surface defects
Except for a marginal area of 5 mm wide, filters shall be free from any material or surface defects likely to impair the intended use, such as bubbles, scratches, inclusions, dull spots, holes, mould marks, scoring or other defects originating from the manufacturing process.
3.5.2 Scattered light
The reduced luminous coefficient (see clause 4 of prEN 167:1991) of a filter shall not be greater than 0,5 cd/rn2
lx
3.6 Stability
3.6.1 Stability to ultraviolet radiation
When exposed for 50 hours as specified in clause 5 of prN 168:1991 the properties f the eye-protectors shall not change to such an extent that they can no longer satisfy the requirements of 3.1 to 3.5. The relative change in the luminous transmittance shall be less than ± 5 %. The spectral transmittance for the laser wavelengths shall, however, in no case exceed the maximum spectral transmittance corresponding to the indicated scale number.
3.6.2 Stability at elevated temperature
After the eye-protectors and filters have been stored for 5 hours in a climatic cabinet at a temperature of (55 ± 2) °C and a relative humidity of at least 95 %, and then stored for at least 2 hours at room temperature, they shall satisfy the requirements of 3.1 to 3.5. The relative change in the luminous transmittance shall be less than ±5 %. The spectral transmittance for the laser wavelength shall, however, in no case exceed the maximum spectral transmittance corresponding to the indicated scale number.
3.7 Ignition
Vhen tested in accordance with 4.7, the frames and filters shall not ignite or continue to glow.
3.8 Field of vision
Eye-protectors shall have a clear field of vision of at least 400 in the vertical and horizontal directions (full anule) (see EN 207, Future 1).
3.9 Construction of filters
Filters shall be constructed so that when tested in accordance with 4.3, no splinters are detached from the side of the filter facing the eye, If the filters consist of several individual filters, they shall be assembled in such a way that they cannot he interchanged,
3.10 Frames
Filters shall not be interchangeable in the frame. The frame shall be designed so that no laser radiation can penetrate from the side unintentionally.
3.11 Mechanical strength
3.11.1 Basic requiremrnl
Filters for protection against laser radiation shall satisfy the static bending requirement as specified
in 7.1.4.1 of prEN 166:1991,
The frames of the eye-protectors shall satisfy the requirements of 7.1.4.2 of prEN 166:1991
3.11.2 Addlllonal requirement
If the mechanical strength of eye-protectors and filters against laser radiation is to satisfy more stringent
requirements, the requirements specified in 7.1.4.2 of prF.N 166:1991.
4 Teat method
4.1 Spectral transmittance
The spectral transmittance is determined for normal incidence. Filters with angular.dependent transmittance (such as interference layers) shall also be measured at an angle of incidence of 30° with polarized radiation. In this case, the scale numberresults from the higheraf the two spectral transmittance values measured.
4.2 LumInous transmittance
The luminous transmittance is determined for normal incidence, relative to the D6. standard illuminant.
4.3 StabIlity to laser radiation
The teat is specified in EN 207. For this, the power densities and energy densities given in Table 2 shall be used for the particular scale numbers. The test period is lOs with the stated power densiLies and 100 pulses with the stated energy densities.
The frame shall be exposed to radiation at the point of least wall thickness for each of the materials (with
the exception of headhands).
The diameter of the laser beam during this test shall be 0,1 mm.
4.4 Refractive value
The test shall be carried out in accordance with clause 3 of EN 167
4.5 Quality of material and surface
The teat shall he carried out in accordance with clauses 4 and 5 of EN 167.
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damaged (e.g by wraith,, sad bob..).
4.6 Stability
The teSt shall be carried out in accordance with clauses 5 and 6 of EN 168.
4.7 IgnItion
The test shall be carried out in accordance with clause 7 of EN 168.
4.8 Field of vision
The test shall be carried out in accordance with 4.8 of EN 207.
4.9 ConstructIon of Alters
The test shall be carried out by means of visual inspection.
4.10 Frames
The frames shall be tested by means of visual inspection.
4.11 MechanIcal strength
The test shall be carried out in accordance with clause 4 of EN 168
5 Instructions for use
The instructions for use shall he in the language(s) of the country in which the eye-protector is sold.
In these instructions for use, it shall be pointed out — e.g. on a sticker, in the case, or on a label — that:
the eye-protector only affords protection against laser radiation:
— up to 0.01 W and up to 2 × 10 J for scale number R 1,
— up to 0,1 Wand up to2 × 105J for scale number R 2,
— up to 1 W and up to 2 × 10 .J for scale number K 3,
— up to 10 V and up to 2 × i0 J for scale number R 4,
— up to 100W and up to 2 × 10-2 J for scale number R 5;
— the eye-protector is not intended to be used for looking directly into the beam;
— that it only offers protection against, occasional radiation exposure where there is no suppression or
reduction (medical treatment, sickness. ..) of the blink reflex; consequently, repeated exposures to
radiation shall be avoided;
— details regarding an appropriate cleaning method.
The luminous transmittance shall be given. If the luminous transmittance is less than 20%, it shall be indicated and the user shall be recommended to increase the intensity of illumination at the workplace. If the eye-protector or filter impairs colour recognition, this shall be indicated in the instructions for use. The instructions for use shall also contain a note to the effect that eye-protectors and filters which are damaged or have undergone a colour change shall not be used any more.
The symbols given in the designation shall be explained.
It shall be pointed out that hazards may arise because of accidental reflection of laser radiation, e.g. by
reflection from reflective parts (including eye-protectors), tilting or maladjustment of optical components.
All personnel working in these areas shall wear eye-protectors.
6 Marking
The following elements shall he marked permanently on the filters or frames for identification.
a) Maximum laser power in W and maximum pulse energy in joules.
b) Wavelength or wavelength range (in nm) for which the eye-protector is specified.
c) Scale number.
d) Manufacturer’s identification mark. In order to prevent multiple use, only marks granted on a
national or European level shall be used.
e) Test mark, if applicable.