red laser use & safety

You could use something like the disks used to draw cut lines for miter saws, one mounted on each side of the rear wheel. The rotation would draw the lines and make it eye-safe. A shield could be used to keep the light where you want it. These use a centrifugal switch to turn them off when not in use (and keep it eye-safe, as well).

On Sun, 30 Aug 2015 09:44:10 -0400, krw Gave us:

They make tail lights for bikes that strike two parallel lines down on the ground about ten feet long with no moving parts.

If sold in the US the product and packaging will have a label advising yo u not to look directly into the beams if there was ever any suspicion the b eams could harm anyone or anything. Sometimes they go overboard but for the se devices, I'd say such a label is appropriate.

I would never use such a device. First, it seems obnoxious to me to carry one's own personal pretend bike lane around. More important is the practic al risk of highly reflective road debris (or water) that could put the beam into the eye of a driver approaching the bike from the rear, making the ca r-bike interaction even more dangerous than usual.

Mark L. Fergerson

Well, from that description, first you heve to get run over by the bike.

On Sun, 30 Aug 2015 11:40:53 +0000 (UTC), unk Gave us:

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.

^^^ oops Non-visible

On Tue, 1 Sep 2015 08:26:30 -0700 (PDT), George Herold Gave us:

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

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 ret ina. The other was the light had to be kept moving. I don't know how safe t hese bike light gizmos are. If I was designing one I would keep the power l evels low at the distances that it might be seen and have the laser shut of f if it stopped scanning.

On Wed, 2 Sep 2015 06:05:33 -0700 (PDT), George Herold Gave us:

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".

On Wed, 2 Sep 2015 09:11:06 -0400, Phil Hobbs Gave us:

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."

On Wed, 2 Sep 2015 06:41:23 -0700 (PDT), Wanderer Gave us:

Bullshit. That is orders of magnitude too much for a direct beam.

On Wed, 2 Sep 2015 06:41:23 -0700 (PDT), Wanderer Gave us:

It is not a "scanning laser", idiot. It is a non-moving line painted by a diffraction grating.

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

That's pretty high even for a short pulse. 80 microwatts would be more like it.

The other was the light had to be

Cheers

Phil Hobbs

I'm sure you're right. Thinking about it walking to the mailbox, I think mi lliwatts had to be wrong. It was like a dozen years ago. Though it was pret ty 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. Thank s