Reply by Wanderer September 2, 20152015-09-02
On Wednesday, September 2, 2015 at 12:04:53 PM UTC-4, Phil Hobbs wrote:
> On 9/2/2015 9:41 AM, Wanderer wrote: > > On Sunday, August 30, 2015 at 7:42:44 AM UTC-4, unk wrote: > >> There is a type of bike light gizmo than uses a laser to draw a > >> line (actually two, two lines) on the road surface behind the > >> bicycle. > >> > >> How safe is this to look directly at? > > > > I used to design the safety circuits for instruments that shone > > lasers into peoples eyes to scan the retina, lens and cornea. There > > were two criteria. One was the power level which ,if I recall > > correctly, was 800mW at the retina. > > That's pretty high even for a short pulse. 80 microwatts would be more > like it. > > The other was the light had to be > > kept moving. I don't know how safe these bike light gizmos are. If I > > was designing one I would keep the power levels low at the distances > > that it might be seen and have the laser shut off if it stopped > > scanning. > > > Cheers > > Phil Hobbs > > > > -- > Dr Philip C D Hobbs > Principal Consultant > ElectroOptical Innovations LLC > Optics, Electro-optics, Photonics, Analog Electronics > > 160 North State Road #203 > Briarcliff Manor NY 10510 > > hobbs at electrooptical dot net > http://electrooptical.net
I'm sure you're right. Thinking about it walking to the mailbox, I think milliwatts had to be wrong. It was like a dozen years ago. Though it was pretty high in the infrared. Something around 1000nm. If you look at the graph for light in water in Photonics Rule of Thumb, the light is attenuated down a lot. It's a book I bought because you recommended it in your book. Thanks
Reply by Phil Hobbs September 2, 20152015-09-02
On 9/2/2015 9:41 AM, Wanderer wrote:
> On Sunday, August 30, 2015 at 7:42:44 AM UTC-4, unk wrote: >> There is a type of bike light gizmo than uses a laser to draw a >> line (actually two, two lines) on the road surface behind the >> bicycle. >> >> How safe is this to look directly at? > > I used to design the safety circuits for instruments that shone > lasers into peoples eyes to scan the retina, lens and cornea. There > were two criteria. One was the power level which ,if I recall > correctly, was 800mW at the retina.
That's pretty high even for a short pulse. 80 microwatts would be more like it. The other was the light had to be
> kept moving. I don't know how safe these bike light gizmos are. If I > was designing one I would keep the power levels low at the distances > that it might be seen and have the laser shut off if it stopped > scanning. >
Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by Phil Hobbs September 2, 20152015-09-02
On 9/2/2015 11:35 AM, DecadentLinuxUserNumeroUno wrote:
> On Wed, 2 Sep 2015 09:11:06 -0400, Phil Hobbs <hobbs@electrooptical.net> > Gave us: > >> On 9/2/2015 9:05 AM, George Herold wrote: >>> On Wednesday, September 2, 2015 at 8:27:37 AM UTC-4, DecadentLinuxUserNumeroUno wrote: >>>> On Tue, 1 Sep 2015 08:26:30 -0700 (PDT), George Herold >>>> <gherold@teachspin.com> Gave us: >>>> >>>>> On Tuesday, September 1, 2015 at 9:46:25 AM UTC-4, DecadentLinuxUserNumeroUno wrote: >>>>>> On Sun, 30 Aug 2015 11:40:53 +0000 (UTC), unk <me@privacy.net> Gave us: >>>>>> >>>>>>> There is a type of bike light gizmo than uses a laser to draw a line >>>>>>> (actually two, two lines) on the road surface behind the bicycle. >>>>>>> >>>>>>> How safe is this to look directly at? >>>>>> >>>>>> Since you are not supposed to "look directly at" ANY laser light >>>>>> emissions, I would say that you need to draw your own conclusions, >>>>>> however that task may also be over your head. >>>>> >>>>> Nah, laser light is just like other light. Too much will cook your eye, >>>>> or fry your optic nerve. About 1 mW into the eye is the "standard" type >>>>> number, (for visible lasers, where your blink reflex kicks in.) That's about the >>>>> same amount of light you get from starring at the sun. (Which can also >>>>> damage your eye if prolonged.) None visible light is more dangerous. >>>>> >>>>> George H. >>>> >>>> You are the same kind of idiot who goes around declaring that ESD is >>>> not a hazard. >>> >>> I'm hesitant to respond, but how is that even related? >>> >>> ESD and diode lasers (which is at least related to lasers) is a huge >>> issue! I had to flip around the current source for our >>> diode laser driver to keep the case at ground.. and added a >>> boat load of ESD protection diodes. I used a piezo-sparker from >>> a butane lighter to test it... The best monitor turned out to >>> be a photodiode looking at the diode laser output. >>> >>> George H. >>> >> >> The issue with laser light vs sunlight is the size of the retinal patch >> that gets illuminated. They eye is very good at focusing a collimated >> beam down to a small spot, which maximizes retinal damage. >> >> Cheers >> >> Phil Hobbs > > And that damage site is a nearly instantaneous event. I cannot > believe he is that stupid. The idiot probably looks into low powered > beams all the time and then says stupid shit like "See... I'm OK."
I doubt that very much. Even 100 uW is enough to cause instantaneous pain, and it would be very difficult to force oneself to stare into a beam that bright. Generally the laser safety regs err very far on the side of caution, but considering the upside vs the downside, that's not a bad plan actually. At the moment I'm in the middle of aligning a lidar system based on a 1W CW Nd:YAG laser (1064 nm). I make sure my goggles are on unless there are two safety features enabled, e.g. putting the laser on standby _and_ closing the shutter. I have a $50 eBay video microscope that can (barely) see the beam, so I don't need to take my glasses off to align it. Even the front surface reflection off an IR-viewing card is enough to be very dangerous with this laser. The lidar is sort of fun--it's designed to detect and (eventually) map particles down to 0.2 microns, moving at up to 3 km/s (Mach 9 at room temperature). It's a pig to align though--I've been putting it off for ages. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by DecadentLinuxUserNumeroUno September 2, 20152015-09-02
On Wed, 2 Sep 2015 06:41:23 -0700 (PDT), Wanderer
<wanderer@dialup4less.com> Gave us:

> If I was designing one I would keep the power levels low at the distances that it might be seen and have the laser shut off if it stopped scanning.
It is not a "scanning laser", idiot. It is a non-moving line painted by a diffraction grating.
Reply by DecadentLinuxUserNumeroUno September 2, 20152015-09-02
On Wed, 2 Sep 2015 06:41:23 -0700 (PDT), Wanderer
<wanderer@dialup4less.com> Gave us:

>One was the power level which ,if I recall correctly, was 800mW at the retina.
Bullshit. That is orders of magnitude too much for a direct beam.
Reply by DecadentLinuxUserNumeroUno September 2, 20152015-09-02
On Wed, 2 Sep 2015 09:11:06 -0400, Phil Hobbs <hobbs@electrooptical.net>
Gave us:

>On 9/2/2015 9:05 AM, George Herold wrote: >> On Wednesday, September 2, 2015 at 8:27:37 AM UTC-4, DecadentLinuxUserNumeroUno wrote: >>> On Tue, 1 Sep 2015 08:26:30 -0700 (PDT), George Herold >>> <gherold@teachspin.com> Gave us: >>> >>>> On Tuesday, September 1, 2015 at 9:46:25 AM UTC-4, DecadentLinuxUserNumeroUno wrote: >>>>> On Sun, 30 Aug 2015 11:40:53 +0000 (UTC), unk <me@privacy.net> Gave us: >>>>> >>>>>> There is a type of bike light gizmo than uses a laser to draw a line >>>>>> (actually two, two lines) on the road surface behind the bicycle. >>>>>> >>>>>> How safe is this to look directly at? >>>>> >>>>> Since you are not supposed to "look directly at" ANY laser light >>>>> emissions, I would say that you need to draw your own conclusions, >>>>> however that task may also be over your head. >>>> >>>> Nah, laser light is just like other light. Too much will cook your eye, >>>> or fry your optic nerve. About 1 mW into the eye is the "standard" type >>>> number, (for visible lasers, where your blink reflex kicks in.) That's about the >>>> same amount of light you get from starring at the sun. (Which can also >>>> damage your eye if prolonged.) None visible light is more dangerous. >>>> >>>> George H. >>> >>> You are the same kind of idiot who goes around declaring that ESD is >>> not a hazard. >> >> I'm hesitant to respond, but how is that even related? >> >> ESD and diode lasers (which is at least related to lasers) is a huge >> issue! I had to flip around the current source for our >> diode laser driver to keep the case at ground.. and added a >> boat load of ESD protection diodes. I used a piezo-sparker from >> a butane lighter to test it... The best monitor turned out to >> be a photodiode looking at the diode laser output. >> >> George H. >> > >The issue with laser light vs sunlight is the size of the retinal patch >that gets illuminated. They eye is very good at focusing a collimated >beam down to a small spot, which maximizes retinal damage. > >Cheers > >Phil Hobbs
And that damage site is a nearly instantaneous event. I cannot believe he is that stupid. The idiot probably looks into low powered beams all the time and then says stupid shit like "See... I'm OK."
Reply by DecadentLinuxUserNumeroUno September 2, 20152015-09-02
On Wed, 2 Sep 2015 06:05:33 -0700 (PDT), George Herold
<gherold@teachspin.com> Gave us:

>On Wednesday, September 2, 2015 at 8:27:37 AM UTC-4, DecadentLinuxUserNumeroUno wrote: >> On Tue, 1 Sep 2015 08:26:30 -0700 (PDT), George Herold >> <gherold@teachspin.com> Gave us: >> >> >On Tuesday, September 1, 2015 at 9:46:25 AM UTC-4, DecadentLinuxUserNumeroUno wrote: >> >> On Sun, 30 Aug 2015 11:40:53 +0000 (UTC), unk <me@privacy.net> Gave us: >> >> >> >> >There is a type of bike light gizmo than uses a laser to draw a line >> >> >(actually two, two lines) on the road surface behind the bicycle. >> >> > >> >> >How safe is this to look directly at? >> >> >> >> Since you are not supposed to "look directly at" ANY laser light >> >> emissions, I would say that you need to draw your own conclusions, >> >> however that task may also be over your head. >> > >> >Nah, laser light is just like other light. Too much will cook your eye, >> >or fry your optic nerve. About 1 mW into the eye is the "standard" type >> >number, (for visible lasers, where your blink reflex kicks in.) That's about the >> >same amount of light you get from starring at the sun. (Which can also >> >damage your eye if prolonged.) None visible light is more dangerous. >> > >> >George H. >> >> You are the same kind of idiot who goes around declaring that ESD is >> not a hazard. > >I'm hesitant to respond, but how is that even related?
Are you really that stupid? YOU claimed that low power lasers are not harmful, and even came very close to saying that they have no potential for harm at all. That is NOT true, and again, idiots like you are the same type of clowns who claim to be engineers, but go around touting ESD as "non-hazardous", or overkill on the part of those taking the precautions. Idiots like you walk across a carpeted floor with a chip or circuit assembly in the palm of your hand. So, I guess you are too stupid to see "how it was even related".
Reply by Wanderer September 2, 20152015-09-02
On Sunday, August 30, 2015 at 7:42:44 AM UTC-4, unk wrote:
> There is a type of bike light gizmo than uses a laser to draw a line > (actually two, two lines) on the road surface behind the bicycle. > > How safe is this to look directly at?
I used to design the safety circuits for instruments that shone lasers into peoples eyes to scan the retina, lens and cornea. There were two criteria. One was the power level which ,if I recall correctly, was 800mW at the retina. The other was the light had to be kept moving. I don't know how safe these bike light gizmos are. If I was designing one I would keep the power levels low at the distances that it might be seen and have the laser shut off if it stopped scanning.
Reply by Phil Hobbs September 2, 20152015-09-02
On 9/2/2015 9:05 AM, George Herold wrote:
> On Wednesday, September 2, 2015 at 8:27:37 AM UTC-4, DecadentLinuxUserNumeroUno wrote: >> On Tue, 1 Sep 2015 08:26:30 -0700 (PDT), George Herold >> <gherold@teachspin.com> Gave us: >> >>> On Tuesday, September 1, 2015 at 9:46:25 AM UTC-4, DecadentLinuxUserNumeroUno wrote: >>>> On Sun, 30 Aug 2015 11:40:53 +0000 (UTC), unk <me@privacy.net> Gave us: >>>> >>>>> There is a type of bike light gizmo than uses a laser to draw a line >>>>> (actually two, two lines) on the road surface behind the bicycle. >>>>> >>>>> How safe is this to look directly at? >>>> >>>> Since you are not supposed to "look directly at" ANY laser light >>>> emissions, I would say that you need to draw your own conclusions, >>>> however that task may also be over your head. >>> >>> Nah, laser light is just like other light. Too much will cook your eye, >>> or fry your optic nerve. About 1 mW into the eye is the "standard" type >>> number, (for visible lasers, where your blink reflex kicks in.) That's about the >>> same amount of light you get from starring at the sun. (Which can also >>> damage your eye if prolonged.) None visible light is more dangerous. >>> >>> George H. >> >> You are the same kind of idiot who goes around declaring that ESD is >> not a hazard. > > I'm hesitant to respond, but how is that even related? > > ESD and diode lasers (which is at least related to lasers) is a huge > issue! I had to flip around the current source for our > diode laser driver to keep the case at ground.. and added a > boat load of ESD protection diodes. I used a piezo-sparker from > a butane lighter to test it... The best monitor turned out to > be a photodiode looking at the diode laser output. > > George H. >
The issue with laser light vs sunlight is the size of the retinal patch that gets illuminated. They eye is very good at focusing a collimated beam down to a small spot, which maximizes retinal damage. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by George Herold September 2, 20152015-09-02
On Wednesday, September 2, 2015 at 8:27:37 AM UTC-4, DecadentLinuxUserNumeroUno wrote:
> On Tue, 1 Sep 2015 08:26:30 -0700 (PDT), George Herold > <gherold@teachspin.com> Gave us: > > >On Tuesday, September 1, 2015 at 9:46:25 AM UTC-4, DecadentLinuxUserNumeroUno wrote: > >> On Sun, 30 Aug 2015 11:40:53 +0000 (UTC), unk <me@privacy.net> Gave us: > >> > >> >There is a type of bike light gizmo than uses a laser to draw a line > >> >(actually two, two lines) on the road surface behind the bicycle. > >> > > >> >How safe is this to look directly at? > >> > >> Since you are not supposed to "look directly at" ANY laser light > >> emissions, I would say that you need to draw your own conclusions, > >> however that task may also be over your head. > > > >Nah, laser light is just like other light. Too much will cook your eye, > >or fry your optic nerve. About 1 mW into the eye is the "standard" type > >number, (for visible lasers, where your blink reflex kicks in.) That's about the > >same amount of light you get from starring at the sun. (Which can also > >damage your eye if prolonged.) None visible light is more dangerous. > > > >George H. > > You are the same kind of idiot who goes around declaring that ESD is > not a hazard.
I'm hesitant to respond, but how is that even related? ESD and diode lasers (which is at least related to lasers) is a huge issue! I had to flip around the current source for our diode laser driver to keep the case at ground.. and added a boat load of ESD protection diodes. I used a piezo-sparker from a butane lighter to test it... The best monitor turned out to be a photodiode looking at the diode laser output. George H.