Question about high quality +200mw lasers.

I'm getting addicted to my x85, but unforunately i cannot leave it on for too long, so i'm thinking about saving funds for a laser with a 100% duty cycle (and a little more power)

Possible options are the Nova200, Hercules250, PPL-225 or RPL200.
Are there any big differences between these models (in performance and quality)?
And is it worth the money to go for an even more powerfull laser which is more than 300mw ?

Important for me are it's burning capabilities and the beam distance(low divergence)

the herc is the only one on that list you are going to be able to leave on for more than a few minutes.

the rpl will be the best burner. the ppl is basically the same as the rpl.


also consider the size:


That's the Herc, and aries/nova and a rpl.

Aseras said:

the herc is the only one on that list you are going to be able to leave on for more than a few minutes.

Click to expand...

Hi Aseras,
I would have to disagree with your above comment.
The run time duty cycle of the RPL (adjustable) is greater than 5 minutes on with a recommended 2 min cooling period if the diode current is adjusted only up to the level where output power no longer increases.

The problem many people have is that they think more diode current means more 532nm power output; this could not be further from the truth.

The reason for this is that the crystal will reach it's IR saturation point. What this means is that an increase in IR diode output will no longer produce an increase in 532nm power output.

The diode current adjustment switch is to "tune" the optimum IR diode output/current, so that no or very little crystal saturation occurs; using the Optotronics provided power cells, the optimum diode current amount will typically be at level 4 or 5.

This level number can increase a notch or two as the battery gets discharged below ~30% capacity or so, or if cells from other manufacturers or mAhr capacities are used, also the impedance (internal resistance) of the battery model can require the use of a higher setting.

An added benefit of the adjustable model is that lower levels of 3 or less will reduce the IR current, that will (since the crystal is not being saturated)at these levels) result in a lower 532nm output power.

To tune and optimized the IR diode current for maximum output. The user begins operation at a low output level, then either visually or preferably with a power meter, observe the output brightness/power.
Then increase the diode current by one level and note if output brightness/power also increases, if it did, then increase another level and repeat the process. When you reach the point where you increase the current, but output does not increase, you turn it back down by one level and you are there.

This process only needs to be done once on a particular battery model/capacity and should be done with a fully charged cell. After that you will know the best operating point for the laser/battery type combination and will only need to repeat this process if you change to a different battery model number.

The mistake most people make is the assumption that level 9 will be the most powerful, when typically level 9 will be 10% or more less than level 4-5 (Using the cell we currently provide with the RPL).
Besides the lower output at level 9, the added IR current, that is not getting converted to 532nm due to the crystal saturation, end up being converted to more heat (which reduces duty cycle).

In fact, we have had many customers report their RPL having 100% duty cycle until the cell can no longer provide power (30 minutes or more), if the diode current is tuned so that crystal saturation does not occur.

Also, when the RPL goes through it test and qualification process, the optimum diode current is determined and noted in the user supplied documents and all power output measurements were made at that same level.

I just wanted to explain this to everyone in a forum posting, and I'm going to take this text and include it in our FAQ.

Thanks
Jack

Hi Jack,

I can run my rpl till the battery is dead on "3" which is about 120mw. The next level of "4" is the highest output on my rpl, ~280mw, it will run there from 3-4 minutes before cutting out and "blinking". Anything beyond 4 is exactly the same on my rpl.

The herc I have on the otherhand though I've run for hours straight putting out a constant 350+mw.

It really depends on what the user wants. The herc has a nice fat pretty beam, the rpl's is thin and tight and so much better for burning popping or such. The herc while having a larger beam also seems to have better divergance, maybe 1/3 or 1/2 as good as the rpl. I've not had a chance to measure it, but it seems really impressive comparing the spot size from the rpl and the herc at over 1000 yards. the rpl is noticable larger than the herc's spot, yet the rpl's beam up close is 1/5 as big as the herc. it's like comparing a pin prick to a pencil eraser.

why not just add a heatsink?

Honestly IMHO I believe the rpl could run indefinetly. It seems to be a current issue rather than a heat issue. Right off the charger when the batteries are fully charged I've see the rpl only last a minute at 4 ( and the rpl goes well into the 350mw+ range too ). after a while once the charges goes down and the rpl levels off to it's rated power of ~260mw ) it'll run longer. The handle gets warm but the "heatsink" doesn't.

Since I got my rpl 2nd hand off of ebay I've completely dissected it. It could also be a heat issue since the crystal set and diode are in an aluminum tower that extends inside of the heatsink area. there's a 5-6 mm air gap between that and the heatsink, so all the heat from the diode has to go out of the handle area to be dissipated. I've considered making a ring of aluminum on the lathe to fill the gap a bit, i'm just afraid of damaging it the laser.

That said, Jack has mentioned that there are some rpl's that have a similar current issue where bypassing or modifying the protection circuit can increase the runtime significantly. I don't recall if he ever followed up on his offer to provide the directions to do that.

Hi Aseras,
Yes I found that the main issue with the diode being shut off is not overheating, but mostly due to the battery protection circuit which prevents the lithium ion cell from discharging too quickly. The circuit senses the battery voltage and current. When the voltage drops below a fixed cutoff point, it shuts the battery current down.
If you try the LG 2600mAhr unprotected cells (since the laser has the protection circuit built into it), you will get much longer run times as the newer, higher capacity cells don't drop their output voltage as quickly. The RPL-260 you got on Ebay was manufactured in October of 2006, the battery protection circuit design was changed in February to lower the battery circuit cutoff voltage and provide longer run time.

I never finished documenting the procedure to modify the circuit as the newer RPLs have decent run time and the rework, disassembly and reassembly is pretty involved and not for the faint at heart; requiring a microscope, a high end soldering station like a MetCal or equivalent, and very good soldering skills.

Jack

Well, thanks for the explanation
But it has made my decision more difficult. :-/
I like the burning capabilities of the RPL but i also like the thick bright beam and run time of the herc.
And i didn't know the herc was so large ( i thought they were all approx the same size )

It will take a few months to save for the funds so i still have time to decide.
Is the herc still a good burner or does the RPL perform significantly better on this?
And what about the Nova series? are they the same as the PPL?

the rpl is by far a better burner. the rpl and the ppl are basically the same, the ppl uses C batteries, the rpl is a newer design and uses 18650 rechargable lithium cells.

the nova's are CNI pgl-iii units. they'd look like the middle laser in the picture I posted. same as the aries by laserglow ( novalasers is laserglow, the novas are a bit beefier with a larger diode than the aries AFAIK ).
I've no personal experience with these, although most who have them like them. The one I have is a 808nm IR laser. It a vastly diffrent beast.

Aseras said:

the rpl is by far a better burner. the rpl and the ppl are basically the same, the ppl uses C batteries, the rpl is a newer design and uses 18650 rechargable lithium cells.

the nova's are CNI pgl-iii units. they'd look like the middle laser in the picture I posted. same as the aries by laserglow ( novalasers is laserglow, the novas are a bit beefier with a larger diode than the aries AFAIK ).
I've no personal experience with these, although most who have them like them. The one I have is a 808nm IR laser. It a vastly diffrent beast.

Click to expand...

Hi Aseras,
Which Herc do you own?

I was wondering, if you get a chance, could you measure spot size on both the RPL and Hercules at say 100ft and 300ft and let us know the results.
It seems strange that at 1000 yds, the Herc spot is smaller than the RPL spot???

Take care
Jack

I'd love to.... but the Herc is in for repair..

It wasn't working correctly on batteries. Worked great on AC power though.
I've not heard what the actual issue is/was yet. When it returns I'll let you know.