Designing and Building a Laser

[Grayne]

Hello all,

I am good at engineering and software development (proficient in every language/architecture out there) but am completely new to electronics and especially lasers and i have a time-sensitive project that consists of a few parts - one of them being a laser device. If you could kindly provide me with any relevant information - i'd really appreciate it as i am honestly overwhelmed by all of the fragmented information out there. Thank you for your time in advance.

Let me first describe what the end result needs to be and then ask questions:

I need to build a portable laser preferably the size and shape of a Preon 1 flashlight that would run on one AAA battery (possible?) and project a diffracted shape clearly visible in daylight/fully lit room only at a maximum of 50". Priorities are weight > size > power consumption > color. I also need to find or machine the housing, tubular preferably. To sum it up: light, small, efficient. Ideally i need 2 of these built identically but i can start with one if i have to.

Questions:

1. Is what i'm set out to do possible (size-wise and battery-wise)?
2. Which components do i need (putting a complete list together is my starting point, i guess the diode is first)?
3. What tools/equipment do i need?
4. Which parts will i have to "manufacture" and which parts are available for purchase? Soldering is something i do have experience with but i'd prefer to save time where possible.
5. Which build/assembly steps can i "outsource" and to whom?

Thank you for your help.

 

[betwixt]

You are asking for one of these:
**broken link removed**

They sell at half of that price on my local market. Everything is done for you and you can remove the lens from one of the 42 supplied tips and change it for one producing the shape you need. It will cost you more than 10 times as much to make one yourself.

The only drawback is the battery. The one in the advert uses 3 x LR44 silver oxide batteries which makes it a fraction wider than a single AAA cell but you have to consider that the laser diode needs about 3V to produce any output so you would need more than one battery anyway.

Brian.

 

[Grayne]

Thank you for the quick reply.

I looked at those and unfortunately due to the nature of the application i need to have a custom housing so buying an already assembled product is out of the question unless it can be a) easily taken apart and b) easily converted to fit the new housing.

Basically i can not do it with 1xAAA battery is what you are saying and i need a Li-MnO2 type? How many hours of continuous use would i get out of it? Is it possible to get all of the components used to build the pointer you linked separately? is there a service that can create the lens i need?

I apologize for so many questions, i am just trying to soak in as much as i can given the short time i have to complete the project.

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Sorry, new to the board, my reply was wiped out somehow (Thanks for merging Mods!).

Basically i need a Li-MnO2 battery then and i absolutely can not do this with one AAA? How much continuous use time does it give me per battery?

Unfortunately due to the nature of the application i can not use any off the shelf product unless i gut it and then install it into my custom housing. Would you (or anyone) know exactly which parts i would need?

Thanks again.

 

[ads-ee]

Take a look at what shows up on google images:
https://www.google.com/search?q=laser+pointer+components&espv=2&biw=1499&bih=867&tbm=isch&imgil=Royg9VlDrrMQiM%253A%253BmwEo1L7xCoMGpM%253Bhttp%25253A%25252F%25252Fwww.globalspec.com%25252Flearnmore%25252Foptical_components_optics%25252Flasers%25252Flaser_pointers&source=iu&pf=m&fir=Royg9VlDrrMQiM%253A%252CmwEo1L7xCoMGpM%252C_&usg=__QtuY2w1DChkaChyUa0t-Zlwyfuo%3D&ved=0ahUKEwirhuLpwtXMAhUI6mMKHSFbDn8QyjcIVQ&ei=Jfs0V-vfPIjUjwOhtrn4Bw#imgrc=-eb_t7RQq4cYhM%3A
As you can see there are a number of items that probably aren't simply things you can buy off of Digikey, etc.

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A laser pointer module could be bought, but I have no idea where you would get the custom end to make the pattern you want or who manufactures them.

 

[c_mitra]

I need to build a portable laser preferably the size and shape of a Preon 1 flashlight that would run on one AAA battery (possible?) and project a diffracted shape clearly visible in daylight/fully lit room only at a maximum of 50". .

You can purchase a laser diode module fully assembled without a battery. one AAA battery will not drive the common LD modules. Either you have to step up the voltage or use at least two AAA (it will not last long).

I am not familiar with a Preon I flashlight (no, I am not interested in googling) but a good engineer will first make a prototype and next consider about the enclosures.

You did not say anything about the intended diffracted shape.

50" is perhaps a bit small: if I am standing in front of the projector screen, it may not cover edge to edge. But if it is open daylight, you are certainly not thinking about a projector screen.

In short, conventional 2-3mW output LD modules should be sufficient- (the beam may be hard to locate in broad daylight) but your other specs are baffling...

 

[BradtheRad]

project a diffracted shape

You might get a shape if you send it through a motorized laser display device.

As I understand it, a laser is a single wavelength. It does not refract. Its beam is extremely narrow. It spreads a small amount over a distance of miles.

For these reasons, whatever lenses you may send it through, it remains a tiny dot.

A convex mirror may disperse the beam somewhat, although the mirror might need to be a tiny ball bearing to get any effect.

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'Diffracted shape'... Does this involve a diffraction grating? If so then I think my post could be irrelevant to what you're doing.

 

[c_mitra]

As I understand it, a laser is a single wavelength. It does not refract.

The statement above is not accurate. Laser beams in the visible, UV and IR regions show refraction consistent with their wavelengths.

The bandwidth (range of wavelengths) of a given laser depends on the cavity (mostly). In common laser diodes, the cavity is so small that the bandwidth tends to be rather large.

The divergence and coherence of solid state laser diodes are far poorer compared to conventional gas discharge tubes (based lasers).

 

[BradtheRad]

I wrote: "It does not refract."

The statement above is not accurate.

You are correct. I guess what I meant was that a laser does not spread to a spectrum when sent through a prism. You get only a single color of a narrow width. Nevertheless it is refracted through the prism, as you point out.

 

[betwixt]

Sorry, new to the board, my reply was wiped out somehow (Thanks for merging Mods!).

Basically i need a Li-MnO2 battery then and i absolutely can not do this with one AAA? How much continuous use time does it give me per battery?

Unfortunately due to the nature of the application i can not use any off the shelf product unless i gut it and then install it into my custom housing. Would you (or anyone) know exactly which parts i would need?

The battery type isn't too important although obviousy one with higher capacity will work for longer. The issue is that laser diodes are relatively hard things to drive, they have a threshold voltage below which they do not exhibit laser action, it varies from one type to another but is usually around the 2V to 4V region. If you want to use a single AAA cell the voltage is simply too low so your options are to use more than one cell or use a boosting converter to increase 1.5V to a higher voltage. Bear in mind there is no free lunch here, you boost the voltage at the expense of drawing additional current so the battery drains even faster. To add to the voltage complication, if you just apply a voltage above threshold to any diode, laser included, it instantly burns out! You have to stabilize the current through it so it stays at safe level and that means extra circuitry between the battery(ies) and the diode. Most laser diodes have a built in sensor that can be used to monitor the light output, you use the monitor output to control the current through the main laser diode to keep it's output constant.

I just checked a small blue laser diode here and at 40mA current it needed 4.85V supply across the diode wires. I would expect a red laser to need a bit less voltage but consider that I took the measurement using a constant current source, if a voltage was put directly acoss the diode it would die pretty quickly! You might be able to find a laser module with a built in regulator board but expect it to need a much higher voltage to supply it.

Regarding diffraction: The pointer I linked to comes with 42 screw on caps over the laser window, they project various shapes including arrows, targetted at kids rather than 'industrial' users but as a source of diffractor it might be useful to salvage the glass from them. I would imagine it extremely difficult to make your own, the glass is only about 3mm (1/8 inch) square.

Brian.

 

[Grayne]

Thank you for the help. I decided to pick up several different housings that i should be able to modify as well as all of the components i think i may need plus several diffraction lenses. Hopefully with more research and work i can make this project happen.