Universal laser protection - Polifilm

Yep, you've only got one spare!

But... orange is orange. These 'laser safety' companies are charging huge money for what is just normal coloured acrylic. They give all sorts of fancy figures, and 'OD' numbers, but what they really do is to buy a bunch of off-the-shelf acrylic and put it through a spectrum analyser - which you can do at home, except the cost of an analyser is more than a sheet of 'laser' acrylic.., but, I just happen to have a transmissive and reflective spectrum analyser and the absorption capabilities of yellow through red acrylic give varying levels of absorption of 445nm light, from over 50% to over 90%.

And I live in the middle of nowhere in SE Asia, where you can't easily buy 'laser safe acrylic'... unless you want to pay US$150 for shipping of a 12"x12" square.

There's nothing special about 'laser safe' acrylic - its just coloured acrylic that naturally absorbs a specific range of frequencies of light. Orange is high up on the visible spectrum - around 640-650nm - which means it doesn't transmit other, lower colours, but passes the range we see as orange.

If you had a blue sheet of acrylic, that's low on the spectrum - 420-470nm, depending on the colour. That would pass a 445nm laser, but block a red diode laser at 640nm

It very much matters a) what kind of laser - diode vs CO2 b) the power of your laser c) IR or visible spectrum d) the opacity of your acrylic.

For IR lasers, even a sheet of clear acrylic will block 95% of IR. But a clear sheet won't do much at all for a visible-light diode... and theres a reason black acrylic is easy to cut - it absorbs all the energy and converts it to heat.

So, don't worry too much about it - if you have a 500mw - 10W 'blue' laser diode, a sheet of 50% orange acrylic will cut down the transmission of harmful rays to a non-harmful level. So will dark sunglasses, but without knowing the colour of the glasses and the frequency of the laser, you are just being stupid to use sunglasses as your primary defence.

And you can test it yourself - get a piece of acrylic you want to test, set your laser at 90deg to the beam, place a piece of tissue paper or other easily burned object and fire up. You won't even be able to scorch light tissue with the beam focused on the paper.

Reflection is the major source of stray coherent light beams in unexpected places. And, unless you're cutting or engraving mirrors 0.o then the reflected beam is going to be significantly lower powered than the beam that struck the object. it will also absorb some of the 'speed' of the beam, shifting it to a lower frequency.

If you want to DIY your laser shielding, get some complementary coloured acrylic and for additional safety some 'one way' reflective film for the inside and you will be fine - but ALWAYS wear your safety specs, even if you have shielding. One accident is all it takes.

I agree with what you are saying. However, for me the decision was that since Tap Plastics was just a few dollars less for orange acrylic shipped to my house then Jtech was, and Jtech took the time to provide me with data I would go with theirs. I could have got the Tap Plastics piece significantly cheaper if I drove to the store, but I started putting a dollar amount on my weekend time and to me it was not worth the gas burned and the hour to hour and a half round trip.

The most powerful laser diode made by man is ~7W - anyone claiming a single diode is more is ‘marketing’ to an easily suckered audience.

As I posted before, any orange/red translucent acrylic will work fine. You can test by firing your laser through the acrylic to rice/tissue paper. You will be unlikely to even scorch it, let alone burn.

One issue is simply the brightness of the beam - it’s tiring on the eyes and even with protection, you should never look at the beam.

I’ve built a number of diode lasers and not used a shield with any of them, but you won’t get in my workshop without proper safety glasses.