Need small diameter (narrow) module for hand build laser pointer (color, power open)

[wb0gaz]

New participant here -

I've got a task to build a laser pointer into a piece of metal tubing (laser diode at one end, wires going through the tubing to electronics at the other end. Looking for recommendation for laser diode module (that can be sourced online in US).

The tubing diameter is the constraint (as thin as possible.) Prefer 7mm OD or less for the laser module (length is unconstrained.) If optics are required, they'd need to be integrated.

From what I've seen in brief online searching, 12mm diameter seems common for a green laser diode module, but that is too large diameter for the application.

Color and power are TBD, this is just to function as a basic laser pointer. Projected form would be a dot.

I'm comfortable with electronics circuit design/construction but have no hands-on experience sourcing/building a laser pointer.

Any recommendations?

Any requests for clarifying requirements?

Does this post belong in another part of laserpointerforums (moderator - feel free to move or modify as needed.)

Thank you.

 

[atomd]

5.6mm laser diodes will be problematic to fit, maybe it's worth switching to 3.8mm. Also most colimating lenses are mounted in M9 mount, so I guess the only option here is to switch to some custom mount, probably some flexure

 

[wb0gaz]

Thank you atomd --

Are laser pointer diode modules usually manufactured with integrated optic lens? If so, what should I look for or avoid to ensure that I don't need to fabricate a mount that supports both the laser diode package and collimating lens?

What is dimension of M9?

Sorry, these are complete beginner questions as I'm just encountering this task for the first time.

 

[Encap]

You need to see what is and is not done and for what reasons rather than chase a daydream based on no knowledge or experience. Have a look on eBay and similar places offering laser pointers to see what is and is not offered would be a start.

The only laser modules available that have an OD of 6mm are low cost 5mW 650nm.
Search "6mm X 10mm laser diode module" on eBay. Several focusable and not focusable can be seen there.

Nobody makes any 7mm OD laser pointers for several reasons. Nobody offers modules that are 6mm OD for 3.8mm laser diodes or offers lenses for use with higher output laser diodes because it is not practical/is a waste of $s, time, and effort.. High output 3.8mm diodes will just overheat and die/fail from thermal runaway within a very very short time. You need as much metal in the module as is practical and marry that with as much metal to metal contact in a host or housing as possible to effectively heat sink more powerful diode and it's module. A thin wall 7mm OD brass tube doesn't cut it in several ways.

 

[wb0gaz]

Thank you, Encap - that gets me much closer. 6x10mm parts at least look workable mechanically (as for thermal, I expect to use low duty cycle, as I'm not looking for high intensity, just compliant packaging.

 

[atomd]

Thank you atomd --

Are laser pointer diode modules usually manufactured with integrated optic lens? If so, what should I look for or avoid to ensure that I don't need to fabricate a mount that supports both the laser diode package and collimating lens?

What is dimension of M9?

Sorry, these are complete beginner questions as I'm just encountering this task for the first time.

This question instantly shows you're from the US M9 is standard 9mm thread.
You could try some tiny collimator like 355390-A from thorlabs. It's small enough to be able to manufacture threaded holder and fit in your 7mm limit.

 

[wb0gaz]

This question instantly shows you're from the US M9 is standard 9mm thread.
You could try some tiny collimator like 355390-A from thorlabs. It's small enough to be able to manufacture threaded holder and fit in your 7mm limit.

Yes, from US, but my work is almost all metric (electronics and related small mechanical components) so did not want take anything for granted here.

My last exposure (so to speak) to lasers as an area of special interest was avid reading of "laser focus magazine" in university library when I was undergraduate EE there (1974-1978). laserpointerforums will make interesting reading as I catch up on the last ~50 years!

 

[wb0gaz]

Question - cut to the chase - is there a typical efficiency spec for a garden variety red low power laser diode as used in a cheap consumer laser pointer ("1mw 5V" is the only spec I have - the ebay posting below says 3V but the writing on the delivery package said 5V, so I'm using that as absolute max.)

Details to follow:

Back again after almost 3 weeks since original posting, much progress (build a very simple red laser pointer that can be embedded in a woodworking project), nearly done.

The basic components for this project are a "1 mW 5V focusable" laser diode (ebay item number 134201973244, about USD 0.80 each, has tiny PCB with 33 ohm SMD resistor in series), thick-wall 300mm long, 7mm OD brass tubing (K&S 9825), four AlkalineLR44 cells in series, additional 27 ohms in series (operating the diode at about 55 mA max, less as batteries lose charge; 55mA was the current draw when the module was directly powered from 4.8V).

I removed about 15mm (of the 300mm) length 240 degrees radially to provide a resting place "cradle" for the diode (tiny amount of thermal material to pass residual heat into the tubing and heatshrink tubing to hold the diode in place) as the diode body diameter - 6mm - fit into the tubing but the tiny PCB containing the 0805 SMD 33 ohm resistor meant that the assembly wouldn't fit into the tubing, hence the "cradle" arrangement.

My question is this - the diode is advertised as 1 mW and is running at 55 mA (near max per the seller's terse specs written on the plastic bag). Can the output power be estimated from the available info (that is, if the input power is ~130 mW, what would be a typical efficiency?) I'm not seeking more (or less) power, just want to be able answer the question (other than parrotting the 1mW claim.)

Thanks again for the replies to my initial posting - they definitely helped get my project off the ground!