IR Pointer...

[mm85]

Alright, I've been thinking about this, just because I like things that are more powerful than they should be, and because infrared power is just as cool to me as a beam. Being that a lot of light energy is lost when the 1064nm lases KTP to become 532nm, what kind of outputs could be gained if the KTP crystal was removed? Also, which crystal in a laser is the first to fail under higher power, KTP or the Nd?

 

[Fussy]

mm85 do you use an ir laser and if so does the ir light come out of it in a beam or like a torch???????

 

[The_LED_Museum]

Without the collimating optics, the beam will very likely emerge from the laser in a fan-shaped configuration. The optics (at least one positive lens) is optimised for the 532nm green laser radiation; I do not know how the beam focus will differ with the 1,064nm laser radiation from the NdYVO4 crystal or the 808nm laser radiation from the pump diode - both are near-IR wavelengths, so you won't be able to adjust the focus with the unaided eye.

 

[mm85]

So the wavelength actually has an effect on the lenses ability to focus divergence? Sounds like I may need different lenses in the pointer if the wavelength is not 532nm. Imagine using a 500mw or even a 1w 808nm diode collimated at full output, no crystal. I wonder what that would do to trashbags?

 

[PocketBeam]

Yes, the lens focuses different wavelenghts differently. I believe it is called chromatic abberations.

Be very very careful. This is a good way to lose vision now, or sometime later. To view the beam, try using a camcorder. Of course the Sony nightshot would work best, but many will see some IR. And beware of reflections from the beam, also know that IR may reflect off surfaces that visible light doesn't.

I am interested in knowing what you find out though.

 

[sharkeeper]

Please remember that many DPSS lasers (with the exception of the most inexpensive pointers) become class IV devices if you just use the output of the pump diode alone!

I have a DPSS laser that uses a 35W bar and that can really hurt you. Don't even think about using such a laser without goggles.

Cheers!

 

[liteglow]

sharkeeper : That image (laser) is the most impressive picture i have ever seen /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif my i wisit u someday haha..

But, i`m new here.. and i wonder what the IR in the laser is(and do), do all laser got it (green\red) ?
Have search some FAQ but did not find the correct answer /ubbthreads/images/graemlins/blush.gif


Is that a second light that HAS to be in there?

 

[sharkeeper]

The camera does not reveal how the IR "looks" in person. The glow is actually a deep red like a much weaker laser. (hence the extreme danger!)

Green lasers are acutally two lasers in one. A 808nM diode which pumps another solid state laser which lases at 1064nM and a frequency doubler which produces a 532nM beam. You (typically) get about 10% of the power (from the pump) although efficiencies vary dramatically by design and envinonmental operating constraints.

Red diode lasers produce output directly from their junctions however the beam is fan shaped and must be corrected with optics to obtain a round beam with low divergence. A simple (grin) lens can do this for the task of pointing and these are available everywhere as cheap pointers.

One day green (and blue and violet!) lasers will be available very cheap just like their red diode pointer counterparts. They will have the same (beam quality) limitations as the red ones we have today. I prefer the beam quality of the DPSS.

Cheers!

 

[mm85]

Sharkeeper what wavelength is the laser in the photo? It's beautiful in that pic. Can a digital camera see infrared, or only a dv camcorder with night ability? What did you use for the pic? Also can a dv cam see all the way to a Co2 output of 10.6m?

 

[sharkeeper]

808 nm

I use a variety of cameras mostly Canon Digitals. They all can "see" near IR well. Nowhere near as sensitive as a Handycam in night view mode, however. Most IR lasers will bloom the heck out of such a camera too!

I wish they could see 10.6 microns. That's deep into the IR and you need a specialty viewer to see that. Of course, most CO2 systems will make typical things around the house light up, no detector needed! /ubbthreads/images/graemlins/smile.gif

Cheers!

 

[mm85]

So could a pointer with no crystals, only the 808nm diode, become a powerful IR device with proper optics? If so, I want to experiment with a cheapie and see what kind of IR output could be realized.

 

[mm85]

So could a pointer with no crystals, only the 808nm diode, become a powerful IR device with proper optics? If so, I want to experiment with a cheapie and see what kind of IR output could be realized.

 

[sharkeeper]

It will be a powerful IR LASER device, however if you need a lot of photons in the IR range, a halogen bulb with a filter puts out hundreds of mW of useable IR.

Then again, a hopped up pointer does too! /ubbthreads/images/graemlins/smile.gif

Just remember, that the duty cycle applies. Those pump diodes are already heavily stressed when the pointer body feels warm in hand. Operation with high current above 40C will put the diode lifetime into hours if not minutes.

Cheers!

p.s. I think the forums server is about to take a dump!

 

[mm85]

Yes the server is getting slow.

What would happen with the lenses from a DPSS laser with only 808nm light being pumped, could you get a decent divergence at all? How could I go about collimating the IR light correctly?

 

[sharkeeper]

The lenses in the pointer will not work. In most pointers, there are a pair of grin lenses to shape and collimate the IR to a sharp point to lase the MCA. The output from the MCA is quite nice but quite divergent so it needs to be expanded then collimated. An IR filter wraps the package right after the expander but before the final collimator.

To use the output from the 808nm pump, you would use a single grin lens and focus it similarly to focusing a red pointer! If you wanted the best beam quality (circular) with lower divergence, a multi-segmented collimator (typically four lenses) is required. Some higher quality firearm sites have these.

One thing to remember! If the lens is far focused, the beam will be very tiny a few feet (or a few yards or more!) and extremely hot. If your diode is putting out 500mW or more and focused to less than 1 mm, it can start fires and burn you like welding slag! If it hits an unprotected eye, forget it!

Cheers!

 

[mm85]

Where could a find a four lens setup to use in a pointer to focus 808nm?

 

[sharkeeper]

Optima Precision has them

Cheers!

 

[mm85]

So if I had a leadlight, swapped the diode with a 500mw, removed crystals, these lenses would install and work perfectly in the body? How could I focus IR if I can't see it?

 

[sharkeeper]

You need to have goggle on anytime you're working with the pump diodes! You can find the threshold of your diode and operate it at that current to align and set focus.

A camcorder or digital cam in ready mode can be used as well. NEVER try adjustments at full power outside of a lab!

The pointer once focused, can be a powerful tool. (toy?) Albeit quite dangerous. A mere 50mW can be used a long ways for surveillance - bouncing the beam off a window and picking up the reflected beam with a pv cell. Hook the pv cell up to a simple 386 based (amp ic not computer) amp and a pair of cheap telex cans and you could probably catch a good glimpse at what people in the room are talking about.

Well, that's a topic for another thread altogether! /ubbthreads/images/graemlins/smile.gif

Cheers!

 

[mm85]

Will my HP digital camera with mpeg recording see IR?