Which laser color for setting flags

[Andy Cross]

Hey I was

Nah! I just had to repair Trump and Rofin lasers. CO2. At this company, they Laser welded sheet metal.
Patriot Missile Sys. Ray domes. They made the backer plate. 2000 were made.
US Marine SUV. Boat looking under carriage. 1000's.
They innovated Laser welded blanks.
Your Prius used laser welded blanks. It reduced the weight by 30%. And made Liberals 80% more likely to die in a major accident.
A major MIS-CONCEPTION that tech. could sweeck out a few more MPG's. IS WRONG. It was lighter vehicles.
I guess. I was wrong.
Andy indicates that using a 5mW laser will make your retinas ash.
As I indicated before. It's all up to the user. Maybe it does not bother you....

Everyone on a Firing Range is required to always wear safety glasses. And hearing protection. There are no set hours of an exception.
So that indicates ANY TIME YOUR ARE ON A FIRING RANGE. YOU HAVE TO WEAR EYE PROTECTION. JUST LIKE IN YOUR JOB.
3 WEEKS AGO A MI SHOOTER WAS ALMOST BLINDED.
AT the next match I saw half the guys take off their glasses.......AND They were aware of the other guys injuries.....

So does Andy wear his eye protection? Prolly not.

.... I was congratulating you on dispelling the myth about lasers. I didn't say that using a 5mW laser will make your retinas ash at all. Reread what I wrote.

And yep I do wear eye protection. Hearing protection and I probably should wear a gas mask when the black powder guys shoot.

And for those who think muffs protect you against the noise well they only protect within the audible range. A lot of damage can still be done by the frequencies we can't hear. Believe it or not.

 

[zippy06]

BS, WOW. Zippy, I was there you were not. I set it up and the original batteries didn't last very long so I put in new unused batteries. Turned it on and walked towards the 100 yd line setting up my flags which didn't take too long. When I got back to the bench there was no light left. C'mon, these things are made in China you don't think the one I had could be a lemon. I've got at least three electronic calipers that also eat batteries. I've got a Fowler that I have to take the battery out when I'm done using it. Don't shoot from the lip, zippy.

yea. I take the batteries out of my Fowler. It's a nice tool. I think, i do it more because it sits in my BR tool box. Not used very often...

 

[zippy06]

.... I was congratulating you on dispelling the myth about lasers. I didn't say that using a 5mW laser will make your retinas ash at all. Reread what I wrote.

And yep I do wear eye protection. Hearing protection and I probably should wear a gas mask when the black powder guys shoot.

And for those who think muffs protect you against the noise well they only protect within the audible range. A lot of damage can still be done by the frequencies we can't hear. Believe it or not.

Okay. sorry. I now realize that was a pro/lib/commie/NAZI political trick. I used to work with a bunch of those. Always had to be on the offensive, for their offensive behavior.....

Andy a friend made a scope set up with a set of 2 D batteries. Quit the work of art. Couple of wires, batteries have covers, scope mount, laser mount, toggle switch, leveling screws, .... I wonder if he went to D batteries for longer life.
Tim B.
Oh, and sometimes I like to just start typing. It's amazing what comes out...............

 

[brickeyee]

...... you are another optical engineer on the forum. Made a number of vicious lasers when I was in the lab. Glad you dispelled the myth about lasers in the one flash and your retinas are ash.

One flash of even lower power lasers WILL easily burn the dot your eye focuses on the retina.

Do it enough times and you may start to have issues.
Do it in the fovea 9the small highly concentrated area in the middle of your visual field) and appears sooner and worse.

 

[brickeyee]

NO Not so much.
Barely burns plastic. Now 8000 Watts for 20 m sec. Nice 25mm circle. Burned half way through 3/8" plexiglass. That's called a "Mode Burn".
To check the optics of the laser. CO2 laser......14 yrs. doing maintenance and repair. Still have my eye balls. Yag lasers require special precautions. Most are solid state.
CO2 laser require gases mixed into the chamber and an electron split off. If I remember correctly 80% Helium, 15% Nitrogen, and 5% CO2. All one step below Hospital grade gases....

I am now retired but after 35+ years my optical lab had nice burn marks all around the wall.

We used about 6 inches as a common setup height.

Did plenty of work on very high power lasers.

100 W on a well collimated small dieter beam with minimal dispersion will create enough heat to leave marks.

It easier to create high power tightly collimated lasers with some technologies.

How you source the beam is not nearly as important is the power level and density you create.

50 years ago I built a CO2 laser that would easily shatter a glass pane in about 10 seconds of operation.

Scared the you now what out of my high school physics teacher.

The window cost about $80 to have the glass replaced.

 

[Boyd Allen]

Personally, I think that Hensler's device is brilliant. I need to get busy and have a friend who owes me a couple of favors make me one. Here is a link relating to lasers and retinal damage.
http://www.pattyvisioncenters.com/index.php/myth_busters/myth/can_laser_pointers_hurt_your_eyes

 

[Jerry H]

Not my idea. I don't know who first came up with it. These were in use at least 20 years ago.

 

[Andy Cross]

By rights I should

One flash of even lower power lasers WILL easily burn the dot your eye focuses on the retina.

Do it enough times and you may start to have issues.
Do it in the fovea 9the small highly concentrated area in the middle of your visual field) and appears sooner and worse.

By rights I should be blind. 17 years ago I was diagnosed with diabetic retinopathy and required laser treatment. They belted both retinas with an argon laser in both the macula and outer regions of the retina over several months. The leakage stopped and the eyes stabilized. I can see no visual effects from the treatment at all. Not sure what the wattage used was but even with the anaesthetic it stung. From what the ophthalmologists told me I would need a lot more treatment before I would. So I don't see how getting the odd ping from a low output laser could do any measurable damage.

 

[brickeyee]

By rights I should be blind. 17 years ago I was diagnosed with diabetic retinopathy and required laser treatment. They belted both retinas with an argon laser in both the macula and outer regions of the retina over several months. The leakage stopped and the eyes stabilized. I can see no visual effects from the treatment at all. Not sure what the wattage used was but even with the anaesthetic it stung. From what the ophthalmologists told me I would need a lot more treatment before I would. So I don't see how getting the odd ping from a low output laser could do any measurable damage.

They very carefully avoid doing any more damage than they have to and use a VERY small spot.

It DOES damage the retina.
That is why a tny scar froms to anchor the retina and help hold it in place.

Detecting tiny spots is a very difficult measurements.
Even detecting larger areas can be hard.
We naturally move our eyes all the time shifting the location of the image on the retina.

This limits saturation effects on any particular area.

Ever seen the 'inverted shadow' after staring at a bright object?
It can show for a few seconds after looking at a bright image and closing your eyes.

The retinal nerves have used up some of the chemicals they use to create nerve impulses from the light.
They tend to replenish quickly and the after image fades away.

The brain smooths everything out so that we hardly detect the almost constant motion of our eyes.

If the eye focuses that little 50 mW down to a few thousandths dot size on the retina what is the power density now?

Did you notice that everyone in the room during your treatment had laser safety glasses on?

 

[Andy Cross]

More info

They very carefully avoid doing any more damage than they have to and use a VERY small spot.

It DOES damage the retina.
That is why a tny scar froms to anchor the retina and help hold it in place.

Detecting tiny spots is a very difficult measurements.
Even detecting larger areas can be hard.
We naturally move our eyes all the time shifting the location of the image on the retina.

This limits saturation effects on any particular area.

Ever seen the 'inverted shadow' after staring at a bright object?
It can show for a few seconds after looking at a bright image and closing your eyes.

The retinal nerves have used up some of the chemicals they use to create nerve impulses from the light.
They tend to replenish quickly and the after image fades away.

The brain smooths everything out so that we hardly detect the almost constant motion of our eyes.

If the eye focuses that little 50 mW down to a few thousandths dot size on the retina what is the power density now?

Did you notice that everyone in the room during your treatment had laser safety glasses on?

The process has undergone some modification since it was first developed. They use a much larger spot now and don't target the leaking blood vessle directly. They put spot burns around the leak a tenth of a mm in diameter . This is a bit like heating up a plastic tube. It shrinks and tightens after about 3 months. Hence the time between treatments. This approach has proven to be much more effective than other methods. According to the ophthalmologists the anaesthetic immobilises the ciliary mussels that alter the shape of the lens so that it cannot alter focus and is stuck at infinity. And no the Dr was looking through the slit lamp and was not wearing any laser protective device. She said you will eventually see the effects of the burns but you need a lot more shots than I have received before it's an issue. I did see the blood vessels in the retina after each shot in a latent image. The next day dark spots appeared which faded out after a day or two. Rather disconcerting.

 

[brickeyee]

The process has undergone some modification since it was first developed. They use a much larger spot now and don't target the leaking blood vessle directly. They put spot burns around the leak a tenth of a mm in diameter . This is a bit like heating up a plastic tube. It shrinks and tightens after about 3 months. Hence the time between treatments. This approach has proven to be much more effective than other methods. According to the ophthalmologists the anaesthetic immobilises the ciliary mussels that alter the shape of the lens so that it cannot alter focus and is stuck at infinity. And no the Dr was looking through the slit lamp and was not wearing any laser protective device. She said you will eventually see the effects of the burns but you need a lot more shots than I have received before it's an issue. I did see the blood vessels in the retina after each shot in a latent image. The next day dark spots appeared which faded out after a day or two. Rather disconcerting.

The damage spots are still there.
The brain learns how to ignore them.

Do not confuse the area used to determine how the spots are placed with the actual spot size.

The spots are tiny, from damaging neurons, and never 'go away.'

Detecting damage or not functioning areas can be a real PITA.
58 years of MS with multiple occurrences of optic neuritis made me learn a huge amount.

I finally had an exacerbation that was close enough to the retina on the optic nerve to create visible palor on the retina.
Every other time the actual affected area was on the optic nerve and NOT in the optic chiasma (since it only affected one eye).

By staring carefully at a complicated object (bookcases of many different appearing books works well) I could start to detect areas I was not 'seeing.'

With the first movement of the eye the brain filled in.

The large illumination you are 'seeing' when the laser is pulsed is from the laser light refracting in the lens of the eye and on the surface of the cornea.
It has nothing to do with the actual spot size the laser has been focused into.

The focusing is done with a very low power non-laser source with a tightly known frequency (color).
The focus mechanism of the equipment is than adjusted for the known difference of focus the actual laser wavelength will have.

The laser was locked off with a safety interlock key if anyone unprotected is in the treatment room.