Do you really think that this is achievable?
Thanks, interesting.
But not sure i will go to this length.
Don't go there. We just found out a lot of imported items from the dollar store have 10x the legal amount of heavy metal contaminants.
So don't eat them.
It's not about what you intend to eat - it's about what you do eat. So as not to go off topic, you can buy laser pointers there too. I suppose they must be 5mW instead of 1mW also. 
I use holiday laser light displays and cover the color I don't want after ripping out the diffuser to get a nice solid beam.
I like to write my name in the sky all willy nilly at night with them.
Totally kidding on that btw. That would be insanely irresponsible for realz (except for the 1st sentence).
Yes, the data presented was from my home lab a few years back. I built the unit, captured the data, ran it thru Excel. It is repeatable...
A common red laser pointer at the center of the blackened cover-slip shows a temperature rise to equilibrium and a temperature drop to ambient.
Again, a calibrated commercial LPM showed the same results, after calibration.
Ray
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My buddy was waving his new 3mW pointer making lines when the line crossed a wide-view mirror he had. The mirror spread the reflection, the event was a moment and then for an hour and a half his right eye saw bright red.
This makes a big dot. A smaller, stronger lens closer to the led; made with threaded plumbing fittings to adjust the lens position by turning the holder. A lockwasher and nut can keep that set finger or wrench tight.
If this is for tag, it's the detectors that you want to limit, not the lights. A detector at the back end of a tibe has a narrow view. It only sees light inside that view pointed at it. And you can play without special goggles.
That would reduce the beam intensity.
Must be zero as it's listed as a sensor. 
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Yea, these sellers scare me, they literally have no idea what they are selling!
Which may be why he only went through 90 minutes scared spitless instead of a lifetime of sorrow.
A big deal with lasers, especially weak ones is the coherence of the beam makes clean interference patterns. Read up to find out uses and cautions before thinking about laser tag, laser goggles and waivers.
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Just to be clear, all i want to achieve is a red dot on the target, tag detection NOT necessary.
Is there an easier way to do this?
With tag detection you can get away with bigger dots better than small dots.
It's about how many sensors the target has to have.
Small dots have to find sensors to be detected, big dots may trigger multiple sensors around the "hit point". With lots of sensors, close misses could be factored. The harness could time inputs for a minimal time before it counts as a hit.
Other thing is the "beam" light can be IR or red (red leds make loads of IR, look at one with your phone) but needs to blink to tell signal apart from ambient light -- same as a TV remote only tight angle. The "shot" could transmit "gun" ID.
Sorry, i completely screwed up that post by leaving out the word "NOT".
Tag detection is NOT NEEDED
One way to guarantee < 1mW is to be really careful to limit the current to it (not really the Voltage). If you put less than 0.5 mA in, then the best imaginable materials, having less than 100% quantum efficiency, could at most deliver 0.5 mA x 1.9 Volts < 1 mWatts. So 0.5 mA is guaranteed to be legal.
That is still too bright to want it dangling on bouncy wires on a pinboard, or pointed carelessly at shiney things which might reflect it. tape and matt black paper stuck over folded cardboard can make reasonable safety backstops for 1mW. -snf- do I smell burning paper ?
More probably for a red, it might take quite a few mA to get to 1 mW. Whether limiting to 0.5mA or 3mA, if you are current limited then you can be sure that the light will be commensurately limited. Hopefully that "5V" package contains a sensible resistor to get a sensible current. Testing with a 1kOhm above that package, and an adjustable Voltage power supply, can you work out what series resistance it has in there as well as the 2V for the red junction? How many mA do you supply it with before the device gets to 5V ?
NOTICE TO ALL BUYERS : numbers on ebay are sometimes uncalibrated exaggerations and not to be trusted. for example the 300 dB bicycle horn. This week I bought a "3000 Watt" food blender which contains a 1000 Watt motor.
The modules I bought came with constant current circuits. Always 20mA 4.5V (5V works fine) or no beam. They have adjustable optics.
I feed the CCC and it feeds the laser. What it takes to start one up is too much once it warms up but if you pre-heat like it's a tube then I bet that a resistor could do.
Don't make this. That's my disclaimer.
This link is quite comprehensive about lasers.
Sam Laserdps
Specifically this page off that is about powering lasers from external power sources.
Powering Lasers