Question regarding IR Filter

Hey there, I'm new to the hobby and recently purchased this product on ebay

https://www.ebay.com/itm/Military-Blue-Purple-Laser-Pointer-405nm-Lazer-Pen-Beam-18650-Battery-Charger/351708574251?hash=item51e376f22b:g:9qUAAOSw2GlXEIyI

I'm fairly certain it does not have an IR filter, which leads me to my question for you guys. Is the lack of IR filter an issue? And if so is there any recommended ones that I can purchase and apply to the unit?

It's recommended that new member make a post the the "welcome" section and introduce themselves and tell us a bit about yourselves. Also it helps if you put your location in your signature, it makes it easier to give better advice.

That being said, you have no need of a ir filter on a 405nm laser. That doesn't mean it still not dangous to the eyes, it still can be. So they still need to be used carefully with wisdom. . Hope that helps and welcome.

Generally, you get a problem with no IR filter on a DPSS-type laser. These use a powerful infrared laser diode shined through a crystal. This is a special material which lets two photons of low energy infrared light at 1064nm combine to form one photon of higher energy 532nm green. A lot of it spills out the aperture without a filter. These days, there are also 520nm green diodes which generally don't put out much IR.

The point being, if this is indeed a 405nm (Blu-ray) it won't have much output in the infrared to filter. It may be a 445nm diode mismarked if it looks more blue than deep purple, but those are also diode-types.

You DO however need proper protection! That particular listing doesn't come with any blue-blocking goggles, and the ones that WOULD come with it could be very insufficient/cheap. Eagle Pair makes the best option I think. If you go to Survival Laser
https://www.survivallaserusa.com/Safety_Goggles/cat1667093_1527285.aspx
you can find a few. Make sure to get goggles that block the wavelength of your laser. There is NO goggle that works on all wavelengths, because it would just block all light and be completely dark!

Thank you for taking the time to to respond and give such detailed answers! I really appreciate the extra information you provided as well

The amount of collimated IR radiation coming from a 532nm laser is very small. I have measure it on several LPMs using an IR filter and have looked at it with my spectrometer. The most I've ever seen was 20% and it wasn't collimated, so it diverges quickly after leaving the output lens. Be more concerned about the light you can see. The one you can't won't hurt you before the visible light blinds you.