Spartan GW 150mW from Dragon Laser - Part 2

[FrancoRob]

In date Feb. 12, 2009 I started a review of a Spartan GW150. While performing a longer P.O. test following the request of brtaman, I noticed abnormal losses of power. After few E-Mail with DL we agreed to send it back for inspection.

Today I have received the new Spartan GW150, and I have to give my warmly thanks to Adam (Sell Dept.) and Frank (Customer Assistance Dept.) of Dragon Laser for the kind and friendly assistance they have given me during the whole check and replacement procedure.

Just to avoid to members jumping fore and aft between my first review and this one, I'm annexing here the same picts. sequence, in which I have changed the Power Output graph with the new one just recorded.

So, Fig. 1 - Spartan two minutes Power Output graph.

Fig. 2 - The Spartan.

Fig. 3 - Beams comparison between the Viper GW95 and the Spartan GW150.

Figure 4: Dimensional comparison (top to bottom) between the IgorT Romisen host, the Viper and the Spartan.

Figure 5, top to bottom: The Viper, the DL Beam Expander with the adapter ring and the Spartan.

Figure 6, top to bottom: the Viper and the Spartan with the BE installed.

Figure 7: The beam coming out from the Beam Expander installed on Spartan.

Hoping this newly updated review will give to the Forum members more assurances about the quality of the DL products and assistance.

 

[MarioMaster]

I always thought the Spartans looked rather blah. Anyways it seems you got a nice unit, I know Amnizu liked his until he managed to break it

 

[FrancoRob]

I regret, but as I started this review I feel the duty to complete it, independently from the results, to respect the Forum readers.

My satisfaction lasted few hours; after the first graphic, recorded in the afternoon of April 2, I dedicated the afternoon time to my lovely grandson (3.5 years old).

Only in the evening, after supper, I found the time to start another longer test to give an answer to brtaman, but I noticed a strong underpower; so I changed the battery of my LaserBee I, I checked the P.O. of my Viper GW95 and my IgorT BR (everyone was showing the usual P.O., 100 - 110mW for the Viper and 154 - 155mW for the IgorT with the new 405-G-1 lens I received from JayRob), then I replaced the DL battery with a TR18650 protected one and I recorded a new graphic as per the annexed Fig. 2.

Not convinced of what was happening, in the early afternoon of the day after (after a recharge of the TR18650 till to see the green light of the charger - it took a short time, as I used it only for the test) I started another test, the relevant recording graphic is in Fig. 3.

I'm not a laser expert, having spent all my working life in aeronautic I can widely speak about aircraft and helicopters structure, flight controls, instrumentation, etc. but my knowledge in electronics design is just a little bit more than zero. I should be pleased to read some hypothesis from more experienced members about this strange behaviour of the Spartan GW150.

Obviously I have informed my DL friends Adam and Frank of the events; I know it's not their fault, but it's clear that for this type of laser, GW150, something is not going as expected. :-/

I thank in advance all Forum members that will dedicate some minutes and some explanations about this topic.

 

[MarioMaster]

Well that's strange - have you bumped it around at all? The only other problems I could see is maybe the pump diode is burning the coating on the crystals, or the pump diode itself is burning out.

Hopefully DL fixes it :-/

 

[FrancoRob]

Oh no, no bumping at all; I left it on a soft rubber layer on my desk... :-/
It's really a pity....

 

[FrancoRob]

This topic is ended. I have received a RMA to allow me to ship back the Spartan to DL..... :-/

 

[randomlugia]

I was surprised to see that the Viper was much brighter in the beamshot. Is it overspec, or just have better divergence?

 

[FrancoRob]

randomlugia:

well, my Viper shows to be a little overspec, as its P.O. (Power Output) exceeds 100mW (I received it in Jan 29, 2008).
I believe it's a problem of mW/sqmm, let me explain:

At a distance of 10 cm, the Viper beam has a diameter of about 1 mm, this means that the beam section area is: 3.14 x 0.5 x 0.5 = 0.785 sqmm

At the same distance, the Spartan beam diameter was about 1.8 mm*, (I say "was" as it is no more in my hands); this means that the beam section area was: 3.14 x 0.9 x 0.9 = 2.54 sqmm

Now it's easy to calculate the specific P.O. per sqmm:

For the Viper:     100mW / 0.785sqmm = 127.0  mW/sqmm
For the Spartan: 170mW*/ 2.54 sqmm =   66.9  mW/sqmm

* I have taken into consideration the value I got in my review Part 1.

So, as you can see, the Spartan shows a specific P.O. having about the half value of the Viper, I think this is why the Viper beam looks brighter....and this is also the reason of the 150mW Spartan model lower burning power: to have the same burning power of the Viper (taking constant the beam diameters), the Spartan P.O. should be:

x/2.54sqmm = 127mW/sqmm, that is: x = 127 x 2.54 = 322.6 mW  

Unfortunately, I didn't check the Spartan divergence value.... but (for my feeling) it was looking to be good...

 

[FrancoRob]

randomlugia:

Mmmm, I understand that my answer may appear to be an over-simplified one, as for a more scientific explanation of the power distribution in a TEM[sub]00[/sub] laser beam it is better to refer to:

http://en.wikipedia.org/wiki/Transverse_mode

as suggested in another topic of this Forum (Lasers - Science & Lasers - Laser Energy Distribution); anyway I think that my explanation may be roughly acceptable.....