488nm Cyan laser - What ND filter would I need to lower the common ebay cyan laser to safe dot viewing

[Nuguns]

This laser Im sure some of you own or have seen is well known to have about 65mw - 70mw. My goal is to get this to 20-30mw area of safe dot viewing with no safety glasses using an ND filter. So what ND filter rating would I need to do this job.

My goal with this laser is to play around inside or maybe even with my cat depending on how she likes lasers and then to remove the said safety filter for night time sky beaming or treetop stuff. I want to have fun inside safely with no worry of glasses. Burning things isnt my intention or interest. This blue is really cool and I wanna have a really nice beam option for outside night time and be able to play inside. I guess Ideally Id go and buy a regular 30mw 488nm laser but Ive only seen those for $250. This one is $65. Please help. I dont own the laser yet.

_____________________________

More in depth rambling- I want to somehow place the filter inside the cap to make it easy to hold and not mess up the magnification, So Im not sure if its possible with this model. It would take some custom work and there might be a good chance Id mess it up fiddling with the laser direction. I feel set on trying to make this work for safety, I wonder if it will be costly to find such ND filter.. I suppose depending on the price Id be ok with even safer around 10-15mw from it. I do want Some power in it beyond a measly 5mw

___________________________________________________

I have learned what the number after ND means; multiplying the light reduction. So that means Id need an ND4 filter to reach safe viewing. on the 488's best day with 70mw divided by 4 is 17.5. With an ND4 filter I could get the laser to have 17.5mw beam. And some quick amazon searching I might be able to get my hands on such a filter for around $25-$50, ideally the cheaper route cause Id probably end up cutting the filter to fit inside the laser.

Now the question is which filter would work best for my intention


This one made for tiny cameras looks great. Idk how Id temporarily attach it to the laser though. its like $10

 

[Nuguns]

after thinking I have an idea. grab a small hinge and super glue it to the filter while making sure the filter is unmoved from a flat position on top of the laser. It should be able to lift up if I want the bright beam

 

[paul1598419]

Eye safe lasers for humans are 5 mW or less. Don't know if there is a difference for cats, but you can get cheap cat friendly lasers very inexpensively at most pet stores. I wouldn't try using a neutral density filter on a higher power one.

 

[Nuguns]

Eye safe lasers for humans are 5 mW or less. Don't know if there is a difference for cats, but you can get cheap cat friendly lasers very inexpensively at most pet stores. I wouldn't try using a neutral density filter on a higher power one.

good to know. I wont use any crazy laser for my cat

I heard somewhere that 30mw was the 'safe' range or lower for peering at the dot and I saw on brainiacs youtube channel where he lowered the reading of a 150mw to 3mw ish using a neutral density filter though that one was adjustable. Still he had others

I could get that the standard and official ratings are 5mw though more common sense would say 30mw probably would be alright used responsibly. Personally, for my potential project id be around 16mw with the ND4 filter. There must be something you know that I dont thats a lot of lasers youve got

_________________

I bought a purple pen laser from aliepress and brainiac had one that looked just like my rated at 50mw. holy sh*t. Its not here yet I think i can assume its gonna be like that

 

[atomd]

1. ND is exponential. ND4 will have transmittance of 10^-4 or 0.1%.
2. Save beam to look at (without optical components like lenses) is just 0.36mW

 

[Nuguns]

1. ND is exponential. ND4 will have transmittance of 10^-4 or 0.1%.
2. Save beam to look at (without optical components like lenses) is just 0.36mW

Ok with the new math that makes an ND4 filter with 70mw to 7mw. So with a ND2 filter Id get like 14mw. Is that right? 70 times .1 or 70 times .2 =

UHHHH so i looked it up it says that math equation is .0001 or -2 is .01 which would bring my laser to .7mw from an ND2 filter. U sure that equation is right man

Look at the reallly dark picture I added in my post, it is a table of light blocking % for ND filters

 

[Nuguns]

ok the video from brainiac Im talking about is his cola video where he takes ND filters, and the video with rechargeable batteries. In that video he uses an ND8 filter on a 50mw purple laser and reduces it to 5mw. that equation is simply 50 divided by 10= 5. So back to ND4 it goes 50 divided by 5 = 10mw. Or with 70mw with ND4= 14mw

 

[Nuguns]

It appears in real life testing a lot of laser gets thru ND filters more than such a rating by equation. Makes sense. Is there anyone here willing to test their lasers with a cheapo ND filter to find some better answers

An ND4 filter would reduce a 50mw-100mw to 10mw-20mw Theoretically

 

[atomd]

I have thorlabs set of lab grade both reflective and absorption ND fitlers and I can assure you that it's base 10 exponent.

Mounted Absorptive Neutral Density Filters

Thorlabs specializes in the building blocks for laser and fiber optic systems. From optomechanical components to telecom test instrumentation, Thorlabs' extensive manufacturing capabilities allow us to ship high quality, well priced components and devices for next-day delivery. Optomechanics...

www.thorlabs.com

 

[Nuguns]

1. ND is exponential. ND4 will have transmittance of 10^-4 or 0.1%.
2. Save beam to look at (without optical components like lenses) is just 0.36mW

Well the math does not reflect the given results check out brainiacs videos where he uses the ND8 filter on a 150mw. I bet its the math of ambient light or wide array or something light like the sun but if you stare at the sun with a telescope you need some SERIOUS dimming. Imagine then the laser is like the sun. That sucker is gona get thru and ur math aint gonna stop it. My mom had a sun filter for staring at the sun thru a large telescope to where you could see sun spots. The ratings are designed behind its intended purpose for cameras and taking pictures.

.........................SIGH i think you werent listening to my research

 

[WizardG]

Oh they were listening to your research all right. You're just wrong and don't want to listen to people here who have been doing this kind of thing for a long time.

 

[kecked]

You’re an arrogant little one….the number in ND IS based on the log. just go buy a cat toy.

 

[atomd]

I feel like this discussion is pointless. Someone bought fake ND filters and now wants to change how world marks ND filters for his one to be right?

 

[kecked]

https://www.bhphotovideo.com/explora/photography/hands-on-review/a-guide-to-neutral-density-filters#:~:text=For%20the%20photographer%2C%20the%20easiest,number%20or%20optical%20density%20number.

now stop saying the earth is flat.

PS if your not a bone head a 1w laser can be safely used with no issues. I think you are asking a lion to be a kitty. Just get a kitty.

 

[Nuguns]

ok guys normally id back off cause this has gotten out of hand and im ineperienced by a lot. Only in braniacs video shows proof of what happens with an ND8 filter with a laser. I really wana discuss these findings no more arguing. Im not sure where you guys are leading me anymore

now stop saying the earth is flat.

PS if your not a bone head a 1w laser can be safely used with no issues. I think you are asking a lion to be a kitty. Just get a kitty.

I want to use the laser like a bone head inside and stare into the dot. Nor do I wanna burn things Ive no interest in that. And Im talking about a, at most 70mw laser never 1w.

So with 70mw a cheap ND4 filter would reduce the power of the light to around 17mw "ish" which is a pretty safe number dont you think

AND.................................. in my original post I already said a 30mw 488nm laser cost 250$ the ebay one is 60$

seriously guys chill out please

 

[Nuguns]

honestly what has gotten into you guys. I wanted to share enthusiasm about the hobby you guys love