Re: [PSES] Automatic measurement with Class 2 laser

[Gary Tornquist]

Visible optical sources that are intense enough to be potentially hazardous are 
painful to look at.  The safety standards assume that an aversion response, 
blinking or looking away, will happen in no longer than 0.25 seconds.  This 
however can be overcome by an act of will, such as when people wished to 
observe the recent total solar eclipse in the USA.  So that is what I think the 
word 'stare' is trying to convey, don't try to overcome the natural human 
reactions.

Could the opportunity for viewing be reduced by narrowing the beam diameter, or 
by pointing it higher or lower than eye level?

Cheers,
Gary Tornquist
Microsoft Corp

Opinions are mine, not necessarily that of my employer.

From: John Woodgate [mailto:j...@woodjohn.uk]
Sent: Sunday, January 21, 2018 11:22 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Automatic measurement with Class 2 laser


Any remote possibility of a reflective surface diverting the beam to a place 
where someone could look at it? I think 'stare' is not a good word: I would 
suggest 'look' for simplicity, but TC82 probably wouldn't agree. There is a 
time element: 'glance' = 1 s, 'look' = 10 s, ''stare' = 30 s.  A 'look' may be 
long enough to cause permanent damage.

John Woodgate OOO-Own Opinions Only

J M Woodgate and Associates 
www.woodjohn.uk<https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.woodjohn.uk=02%7C01%7Cgarytor%40microsoft.com%7Cbfd05770aea147b3a55408d56168e44b%7Cee3303d7fb734b0c8589bcd847f1c277%7C1%7C0%7C636522025491856026=4IaMmo1oAQFwK2tPfabT6xrC09TU7EtG4jOL%2B90jydE%3D=0>

Rayleigh, Essex UK
On 2018-01-21 20:48, Charlie Blackham wrote:
All

Class 2 lasers are required to be fitted with a warning against staring 
directly into the beam

Whilst "stare" is not defined in EN 60825-1, the following is stated

However, dazzle, flash-blindness and afterimages may be caused by a beam from a 
Class 2 laser product, particularly under low ambient light conditions. This 
may have indirect general safety implications resulting from temporary 
disturbance of vision or from startle reactions. Such visual disturbances could 
be of particular concern if experienced while performing safety-critical 
operations such as working with machines or at height, with high voltages or 
driving.

Users are instructed by labelling not to stare into the beam, i.e. to perform 
active protective reactions by moving the head or closing the eyes and to avoid 
continued intentional intrabeam viewing.

The application I'm looking at involves a wireless connected laser distance 
measuring device making an automated measurement every 12 hours of the distance 
to a structure or tunnel wall for example. Provided that it is not installed in 
a location where someone could experience an unsafe startle reaction, as 
discussed above, are there any other issues I should be looking at and anything 
to prevent the installation of such an automated device?

Thanks
Charlie

Charlie Blackham
Sulis Consultants Ltd
Mead House
Longwater Road
Eversley
RG27 0NW
UK
Tel: +44 (0)7946 624317
Email: char...@sulisconsultants.com<mailto:char...@sulisconsultants.com>
Web: 
www.sulisconsultants.com<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Foutlook.hslive.net%2Fowa%2Fredir.aspx%3FC%3D02be3bf3e3a544d1bdf7b6c99fbd12f5%26URL%3Dhttp%253a%252f%252fwww.sulisconsultants.com%252f=02%7C01%7Cgarytor%40microsoft.com%7Cbfd05770aea147b3a55408d56168e44b%7Cee3303d7fb734b0c8589bcd847f1c277%7C1%7C0%7C636522025491856026=QW%2Bd1xrqlrHUCvt4XQT4EmFATUlUp7KMpyEWhN%2Blkx0%3D=0>
Registered in England and Wales, number 05466247

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Re: [PSES] Automatic measurement with Class 2 laser

[James Pawson (U3C)]

Hi Charlie,

 

A slight aside: I'm not a laser expert, but is there a way of soft starting
the laser over the course of a couple of seconds, perhaps via PWM, that
could be used to mitigate the hazard associated with sudden beam appearance?

 

All the best

James

 

 

From: Charlie Blackham [mailto:char...@sulisconsultants.com] 
Sent: 21 January 2018 20:49
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Automatic measurement with Class 2 laser

 

All

 

Class 2 lasers are required to be fitted with a warning against staring
directly into the beam

 

Whilst "stare" is not defined in EN 60825-1, the following is stated

 

However, dazzle, flash-blindness and afterimages may be caused by a beam
from a Class 2 laser product, particularly under low ambient light
conditions. This may have indirect general safety implications resulting
from temporary disturbance of vision or from startle reactions. Such visual
disturbances could be of particular concern if experienced while performing
safety-critical operations such as working with machines or at height, with
high voltages or driving.

 

Users are instructed by labelling not to stare into the beam, i.e. to
perform active protective reactions by moving the head or closing the eyes
and to avoid continued intentional intrabeam viewing.

 

The application I'm looking at involves a wireless connected laser distance
measuring device making an automated measurement every 12 hours of the
distance to a structure or tunnel wall for example. Provided that it is not
installed in a location where someone could experience an unsafe startle
reaction, as discussed above, are there any other issues I should be looking
at and anything to prevent the installation of such an automated device?

 

Thanks

Charlie

 

Charlie Blackham

Sulis Consultants Ltd

Mead House

Longwater Road

Eversley

RG27 0NW

UK

Tel: +44 (0)7946 624317

Email:   char...@sulisconsultants.com

Web:
 www.sulisconsultants.com

Registered in England and Wales, number 05466247

 

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Re: [PSES] Automatic measurement with Class 2 laser

[John Woodgate]

Any remote possibility of a reflective surface diverting the beam to a 
place where someone could look at it? I think 'stare' is not a good 
word: I would suggest 'look' for simplicity, but TC82 probably wouldn't 
agree. There is a time element: 'glance' = 1 s, 'look' = 10 s, ''stare' 
= 30 s.  A 'look' may be long enough to cause permanent damage.


John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK

On 2018-01-21 20:48, Charlie Blackham wrote:


All

Class 2 lasers are required to be fitted with a warning against 
staring directly into the beam


Whilst “stare” is not defined in EN 60825-1, the following is stated

However, dazzle, flash-blindness and afterimages may be caused by a 
beam from a Class 2 laser product, particularly under low ambient 
light conditions. This may have indirect general safety implications 
resulting from temporary disturbance of vision or from startle 
reactions. Such visual disturbances could be of particular concern if 
experienced while performing safety-critical operations such as 
working with machines or at height, with high voltages or driving.


Users are instructed by labelling not to stare into the beam, i.e. to 
perform active protective reactions by moving the head or closing the 
eyes and to avoid continued intentional intrabeam viewing.


The application I’m looking at involves a wireless connected laser 
distance measuring device making an automated measurement every 12 
hours of the distance to a structure or tunnel wall for example. 
Provided that it is not installed in a location where someone could 
experience an unsafe startle reaction, as discussed above, are there 
any other issues I should be looking at and anything to prevent the 
installation of such an automated device?


Thanks

Charlie

*Charlie Blackham*

*Sulis Consultants Ltd*

*Mead House*

*Longwater Road*

*Eversley*

*RG27 0NW*

*UK*

*Tel: +44 (0)7946 624317*

*Email: char...@sulisconsultants.com 
*


*Web: **www.sulisconsultants.com* 



Registered in England and Wales, number 05466247

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