#3 for me please
EDIT:
My Mini-Laser Host Review:
(A regular review with its own thread will come later when I have photographs showing the host in operation).
I bought one, very nice. Made uber slender with the 14500 battery profile (ID for the batteries inside is the same size as 2 X AA in series). I have used a single mode blue 445nm diode in mine, relatively low power of 200mw for blue, but a great little host. I bought 14500 batteries on ebay for it for under 3 dollars each but still waiting for them to arrive. The unit has a black and red wire inside to hook up to a DTR 12mm diameter Aixiz module, red goes to the spring near the laser diode end of the tube. If hooking the red wire to the laser diode module's positive lead the batteries go in like a normal flashlight but it appears you can wire it either way, case negative or positive if you wish, depending upon the configuration of your laser diode. The head with its matching threaded cap allows you to vary the focus of the beam using a Aixiz G2 type of threaded M9x0.5 lens holder (which you can get with a DTR module, or 3 element M9x0.5 lens assembly for lower divergence).
Due to the small size and lower capacity batteries this unit uses, this host is better suited to lower powered laser diodes and to get the most bang for your milliwatts, 520nm green is the color to use due to the heightened sensitivity of our eyes to green compared to blue or red, milliwatt for milliwatt the beam of a 520nm green laser is viewed to be close to 10 times brighter than 445nm blue or 638nm red and the spot intensity near double that at near 20X. With the two 14500 batteries in series (for up to 8 volts when freshly charged) you can use a 120mw 520nm green laser diode in a *Aixiz module with plenty of battery capacity which will have a brighter beam than a 1 watt blue or red laser with a longer visible throw than the other colors, to borrow a flashlight term, especially when using a 3 element lens which has higher loss than a single element G2 lens, but will produce far more concentrated light at a distance due to the physics of divergence.
When I received this host, even after viewing the photographs in this thread, I was surprised how small it really is. The price might seem high for a little host, but I wouldn't want to spend the amount of time it takes to make one of these for less than 50 dollars myself, in fact, for that price I wouldn't even do it unless retired and doing this for the love of the work.
*Use a constant current regulator inside the DTR or Aixiz module for this host, there is no room for one to be placed elsewhere in the unit.
Note: I believe this host could be used with much higher power output laser diode modules, but the user must be very mindful of the duty cycle, or how long the laser operates due to how fast the diode can warm up and possibly overheat if such care isn't taken. Since the head and body of the laser are cut from one solid piece of aluminum without joints, the body of the host will also radiate heat away from the diode, because of this there is more area to dissipate heat than some larger hosts which are made from more than one piece.
DTR 120mw 520nm modules:
https://sites.google.com/site/dtrlpf/home/diodes/osram-plp520
Datasheet for 120mw 520nm LD:
https://drive.google.com/file/d/0B_6-KC5wFXIJRk5MYXQ0M2YzQkk/edit?pli=1
Don't let it's small size fool you, awesome things can be done with such a small host!
MAKE THIS LITTLE HOST UBER AWESOME: I'm trying to sell the idea of using single-mode laser diodes with three element lenses because too few seem to understand that at a distance they can outperform the higher power laser pointers which use multi-mode diodes and a lower loss G2 lens because their lower divergence allows them to catch up and overtake the spot producing brilliance of some lasers which are ten times more powerful, so here's the soap box rant:
Build this host with as high a power single-mode 520nm laser diode you can find with a 3 element lens and you will be able to shoot a beam with a tighter spot with more intensity at a distance than some of the 1+ watt green multi-mode diode lasers which cost hundreds of dollars more. The reason for this is that single-mode diodes produce less divergence than the higher power multi-mode diodes and when paired with a three element lens, which further reduces the divergence, deliver more light in a tighter spot at a greater distance than the high power multi-mode diodes can.
Add a 20X beam expander on the end and you can push a tighter beam even further with a brighter terminus spot than any of the high power laser pointers without such a combination to produce a spot twenty times smaller in diameter at a given distance (of over a quarter mile away) than any of the lasers without expanders can do, low divergence diodes or lenses not withstanding. Adding a beam expander to a laser which already has low divergence due to using a single-mode diode and three element lens brings you to a whole new level of performance as expanding the beam further reduces the divergence beyond what a multi-mode diode laser pointer could do, even if they added the same beam expander.
As of this writing, spending over an hour adding more information, I've just convinced myself to swap out my 200mw 445nm blue laser diode already installed in the host to a 50mw rated 520nm green single-mode diode for about 80mw out (they can safely be pushed harder to about that). Here's the single mode DTR moduled 520nm diode I will use for it (already have): https://sites.google.com/site/dtrlpf/home/diodes/pl520-520nm-laser-diode
