Laser Power Meter < 2 W

[michelrietveld]

and what is connected to the tec +in and -In ??
i would expect a photon cell or something like that.
or does it measure heat?

[borgqueenx]

Forget my pm, it was the radiant elektronics meter.
Its 100dollar, you can search for it on LPF and pm the topic creator. Maybe you will get a faster reply
Good luck

[lasersbee]

hey jerry i also found the zero pot usless replaced it with a 10k multi turn pot been fine since, as for being accurate mine with in 5mw ,ie if i put it in front of one of my 640's it reads 145mw and if try on my 1050mw green i get 1055mw other than like you say its slow
it makes a great hobby meter when funds dont allow for a better one. +- 5mw good enough for me
i have had a laserbee before, highly recomended very good for the price
the only reason i did not buy another was shipping and import costs took me over budget

Hey badger...
thanks for the kind words on the LaserBee..

If you would calibrate it at 1/2 range... then any errors would divide by half at
the extremes...
When I get the Alpha back in my hands I'll try the 10K pot idea. Thanks.
Yeah... the alpha circuit is better than sticking your finger into the Laser's beam
to get a power reading...LOL

I understand what you are saying about the shipping costs...
It is so cheap to ship anywhere in the world from the USA. Canada Post
kills us when we ship internationally and of course the customer must pay
for those shipping costs.


@michelrietveld....
as shown on the schematic.. the input is connected to a TEC (Thermal
Electric Cooler). The Alpha uses a 15mm square TEC from Mouser.
You can also get them from DigiKey. They will cost <$20.00

As I've mentioned before...he TECs we use on the LaserBee products
as Thermopiles... are specially manufactured for us to our specs and
cost just under $60.00 ea in large quantities.

@borgqueenx...
They are always out of stock... It's been that way since day one..
You would think that they would build more than 2 or 3 at a time like
a serious business would do... rather than leave potential customers
hanging...
Maybe they are creating a need to have.... Hmmm


Jerry

[MarioMaster]

Yeah dnar... I had one in my hands a while ago..
They suck the life out of 9Volt batteries at >250mA
current draw.

Current draw of the Alphas are now 105mA, which is around the same, maybe even less than a laserbee with the LCD backlight turned on. Several customers have actually reported that the battery lasts a long time, and no complaints about it not lasting long enough.



It takes quite a long time to stabilize to a power reading.
If you test a 1000mW Laser it takes about 40 seconds to
get to 950mW then about another 30 seconds to get to 1000mW.

This is due to the thermal mass of the sensor - I'd rather have a sensor that will fit the whole beam even if it takes a while to stabilize. Also, laserbees exhibit the same behavior although not to the same extent as they use the same thing as the sensor, a TEC - just a smaller one.

We also found that the Alpha is probably calibrated at 100mW.
That was the only power that it was accurate at. Near 1200mW
we saw errors of +136mW. It was always over reporting above
100mW and under reporting under 100mW.
Still not bad for $100.00 built.

Alphas a calibrated with a temperature stabilized laser diode at full range.

The other thing we didn't like was that you could not Zero the
meter after a few tests. The zeroing knob became useless.


It also does not have Peak Detection. Probably not useful anyway
since the response is so slow it would no doubt miss the Peak.

This is a known and acknowledged problem from the original batch - and new potentiometers were given out for free to customers of the first batch. All new Alphas come with the newer ones included. Variations in the op-amps from the factory cause some units to be less responsive to the zeroing system which is why this problem didn't show up on the prototype or first few commercial units.

We will be getting a hold of that same Alpha again and will be
developing a Data Logging Interface ad-on that can be used on
our 5Watt LaserBee (that we sell on eBay as of today).. the "nospin"
5Watt LPM and the Alpha.

Like I said the Alpha is worth the $100.00 they are asking for it.
They are always out of stock since the launch... They must be
building them in batches of 1....LOL

Well, school comes first. My schedule doesn't have much free time this semester except weekends, which is when I usually work on building more units.

Here is a Schematic of the Alpha circuit... You could build your
own Alpha LPM for about $25.00....

Attachment 23328


Jerry

Yes, you CAN build you own - this is why I posted it for everyone to see on LPF - it's also been built by users here.

and what is connected to the tec +in and -In ??
i would expect a photon cell or something like that.
or does it measure heat?

Optical power meters are unreliable by design especially if your laser is emitting more than one wavelength. IR leakage from a green laser can significantly throw off readings since optical sensors have different responses for different wavelengths.

The Alpha and Laserbee power meters use TECs to convert the heat of the laser to an electrical signal.

Hey badger...
thanks for the kind words on the LaserBee..

If you would calibrate it at 1/2 range... then any errors would divide by half at
the extremes...
When I get the Alpha back in my hands I'll try the 10K pot idea. Thanks.
Yeah... the alpha circuit is better than sticking your finger into the Laser's beam
to get a power reading...LOL

I understand what you are saying about the shipping costs...
It is so cheap to ship anywhere in the world from the USA. Canada Post
kills us when we ship internationally and of course the customer must pay
for those shipping costs.


@michelrietveld....
as shown on the schematic.. the input is connected to a TEC (Thermal
Electric Cooler). The Alpha uses a 15mm square TEC from Mouser.
You can also get them from DigiKey. They will cost <$20.00

As I've mentioned before...he TECs we use on the LaserBee products
as Thermopiles... are specially manufactured for us to our specs and
cost just under $60.00 ea in large quantities.

@borgqueenx...
They are always out of stock... It's been that way since day one..
You would think that they would build more than 2 or 3 at a time like
a serious business would do... rather than leave potential customers
hanging...
Maybe they are creating a need to have.... Hmmm


Jerry

I'm surprised you waited this long to bash my meters here Jerry


Also if anyone is ever unhappy with their Alpha, they are welcome to send it back for a full refund.

[lasersbee]

I'm surprised you waited this long to bash my meters here Jerry

I don't see any bashing MM...

I stated it was worth $100.00...
If you think that is bashing... you are grasping at straws...

I'm just stating honest first hand facts...


Jerry

[badger1666]

i dont care how crude and slow this design is, it works
and is good enough for my hobby use, fairly acurate too. once calibrated correctly.
and for what it costs to build i can live with the 40secs it takes for me to get a reading
give the laser chance to stabalise
its been great for alighning my 640nm 6 diode build
thanks to mario master for making a power meter affordable for me and others
gerry your meters are good too
cheap power meters have there down sides but i can live with it

please lets not have a mines better than yours pissing match please
there are other forums for that

[MarioMaster]

I don't see any bashing MM...

I stated it was worth $100.00...
If you think that is bashing... you are grasping at straws...

I'm just stating honest first hand facts...


Jerry

You wouldn't have typed out that giant post if you didn't have problems with me selling my meters.

[MarioMaster]

i dont care how crude and slow this design is, it works
and is good enough for my hobby use, fairly acurate too. once calibrated correctly.
and for what it costs to build i can live with the 40secs it takes for me to get a reading
give the laser chance to stabalise
its been great for alighning my 640nm 6 diode build
thanks to mario master for making a power meter affordable for me and others
gerry your meters are good too
cheap power meters have there down sides but i can live with it

please lets not have a mines better than yours pissing match please
there are other forums for that

Thanks, and that's exactly what these meters are, and why they're $99.95

[lasersbee]

i dont care how crude and slow this design is, it works
and is good enough for my hobby use, fairly acurate too. once calibrated correctly.
and for what it costs to build i can live with the 40secs it takes for me to get a reading
give the laser chance to stabalise
its been great for alighning my 640nm 6 diode build
thanks to mario master for making a power meter affordable for me and others
gerry your meters are good too
cheap power meters have there down sides but i can live with it

please lets not have a mines better than yours pissing match please
there are other forums for that

I agree with you... if the meter that you built is doing the job for you...
then that is all that is important.
I even posted MM LPM here with his name on it... how is that bashing
There is no pissing match here... I've never compared MM's lpm to our
Laser Power Meter... MM does it for us...

@MM
Here MM I'll say it one more time.... your Alpha is a good cheap meter.
BTW...That's not bashing.....

Bashing is what you try to do to me and my products on LaserChat...


Jerry

[mccarrot]

Just buy a decent head and connect it a multimeter.

Like this: http://cgi.ebay.com/Ophir-OEM-Broadb...#ht_518wt_1139

If you use a multimeter with datalogging or PC connecions you can even make nice graphs/