The message is a little long - don’t buy eBay uncertified rubbish - but there’s a salient point that I had not heard before.
There is the potential for other wavelengths to be created by cheap lasers. In the video, there’s discussion around infrared laser light also being generated in addition to the light that’s specified by the laser, in our case 450nm (for a SM2), 405nm (for SM Original) and 445nm (for the SM Original High Power module).
The video makes the case that you need to take this into consideration for some lasers.
Is there anyone who has measured the actual output of the SM2 laser?
The Wavelength for Infrared is 800nm to 1mm, which is a wide range.
Meanwhile, I’ve also been hunting down information about the potential for infrared being part of the output. This could be an issue if the glasses don’t filter those out. I have not found a definitive source yet, but, wikipedia has the following text[1] on the matter:
Blue lasers can also be fabricated directly with InGaN semiconductors, which produce blue light without frequency doubling. 450 nm (447 nm ± 5 nm) blue laser diodes are currently available on the open market. Some blue diodes are capable of very high power; such as Nichia’s NDB7K75 diode, which can continuously output over 5 watts if overdriven. The devices are brighter for the same power than 405 nm violet laser diodes, since the longer wavelength is closer to the peak sensitivity of the human eye. Mass production of laser diodes for commercial devices like laser projectors have driven down prices. Recent popularity of the high-power version of these 447 nm pointers, which also have improved optics for better collimation and lower divergence, rivals the hazards associated with the use of these portable devices by persons of questionable intention and cost has diminished to be competitive with DPSS green lasers wavelengths.
The salient point in the above quote is “without frequency doubling”, which I understand to mean that it doesn’t contain wavelengths of 900nm, which would be infrared, so glasses that only filter out 450nm should suffice.
Yes, that calculator you linked doesn’t specify the exact method it uses, but conveniently both EN208 and ANSIZ136.1 both give a result of 3.2.
With EN208 1mW of CW laser light admittance through the goggles is intended for alignment purposes, and can be sufficiently protected by the eyes blink reflex. It’s intended for diffuse viewing. With EN207 for full protection the calculation is more complicated and I haven’t done that. For EN208, 1600mW/103.2=1.0mW
However, as I’m in the states, we instead fall under ANSI Z136.1, which specifies an MPE for a 450nm laser being viewed for extended time is 0.1mW/cm2. A rough estimate of that would involve estimating the beam divergence and the viewing distance. I estimated 2 degree divergence, and guessed a viewing distance of 1m. Conveniently, that would put the beam intensity at 160mW/cm2 which would require the exact same goggles: log10(H0/MPE) = log101600 = 3.2.
How was it dealing with LSI? I’ve had one reply to my four emails since 11 November. It answered several questions, but it closed with “I’ll look into it”, nothing since.
I’m getting to the point where I’m wondering what kind of organisation it is. I know another SM owner here who has had similar challenges getting a response.
Onno,
I had a great experience from Laser Safety but I called them rather than e-mailing as I gather they are a reasonably small company. Based on the Holiday Season and Covid-19 being prevalent in the US it would not surprise me if they are short staffed for the the time being. If you haven’t already I suggest pinging them again
I did wonder about the pandemic situation in Minnesota - which looks to be increasingly poor.
I have pinged them via email, several times. Calling was on my to-do list, we’re 14 hours ahead, so I need to call early in the morning here, hopefully before they finish for the day.
Not sure of the best course of action at this point. It would be good if I can get some safety glasses here before my SM arrives
Hey all,
thanks for the interessting read. Will definitely get some better safety goggles (thanks @Melanchrom for the link) but also need to take care of two cats. Since the official enclosure only delivers OD1.something this won’t be a option and so far I haven’t seen laser safety goggles for cats…
The easiest would be to put the machine into a shelf and enclose it with intransparent material (wood, acrylic etc.) I guess but being able to see what the machine is actually doing would be very interessting especially at the beginning of using it.
I tried googling some alternatives and in some german laser engraver forums they recommend Plexiglass 2C04 (orange acrylic) which has a transmission of 0,06% for 450nm (still looking for a comfirmation, only found linear scaled spectra so far). So this would actually equal the mentioned minimum OD 3.2 but since it’s more a exemplary measurement than a certificate i was thinking of applying additional yellow foil to it. One foil I found is Soldera SOL-GLF which has a transmission of ca. 5% at 450nm.
With applying such a foil to both sides of the acrylic this would add up to OD 5.8 in the best case (please correct me if i got the math wrong ). At least the recommended OD 3.2 should be more or less certainly be achieved and the price would add up to ~150€/m² (~85€/m² for acrylic and ~30€/m² for the foil) for more design flexibility which is acceptable I guess.
I’m still looking for better yellow foils like for example this: Lithoprotect but haven’t found a retail seller yet…
What do you think, is this a reasonable approach or is this something to forget and rather follow the safe way and place the machine in an opaque enclosure?
The official enclosure hasn’t been certified yet as far as I know.
But there are two considerations to make:
Reports of gaps in the enclosure plus the delivered safety goggles are equal to the optical properties of the safety goggles alone in the worst case (OD 1.19 as I read). That’s why one should get proper safety goggles.
Given the price point i wouldn’t expect the used material to exceed OD 3
Those are of course only my thoughts. In the end the safest approach is to make sure no light can be emitted at all (opaque enclosure) and to hook up a camera e.g. through OptoPrint.
Trying to figure out what to get. Found Uvex Laservision
Would a P1L02 Filter do the trick for goggles
3125-532nm has a OD of 8+
D&I as the laser is pulsed in quite shorte pulses
D = LB6 | I = LB7
and potentialy replacement Windows made of
P5L03 (OD5+) or P5N01
Meassuring the Doors/Sides, ~ 3mm thick.
P5L03, P5N01 with 3mm each and ~OD5 could be an option.
Seems that they actually are switching the Laser Safety Goggles to better suited ones. At least in the newer Version of the Quick Start Guide (V1.3.0) they state that the provided glasses are OD6+:
). At least the recommended OD 3.2 should be more or less certainly be achieved and the price would add up to ~150€/m² (~85€/m² for acrylic and ~30€/m² for the foil) for more design flexibility which is acceptable I guess.