DT 40 Pro set or......

[steve-o]

Jian-
Just trying to clear something up- what is the 400-660nm reflectivity on your present mirrors? >90%? >95%?

[jian725]

Jian-
Just trying to clear something up- what is the 400-660nm reflectivity on your present mirrors? >90%? >95%?

Hi Steve,
Sorry,I haven't laser power meter on hand.
I think most people have this misconceive in lasershow system.
http://www.photonlexicon.com/forums/...?t=2154&page=4

Seem no anyone discuss how many loss at the laser of the modulation!!!

Even the mirror loss 10%,but is that your lasershow always runing at 90% power output???
Maybe,if you cut the modulation.

At fact when the laser of the modulation at 2Khz ,your laser output almost just 30% output,40% is the very good performance laser.

That loss 60%-70%!!!!!!!!!!!!!!!!!

e.g.
You buy one 1W green laser for your laser system.
hypothesis the galvo's mirror reflectivity 99.9%.
When the modulation up to 2Khz,the laser output about 300-400mw only!!!
If you buy the 10Khz modulation laser,maybe at 2Khz just 500-600mw output!!!

So DT40pro scanner using dielectric mirrors.
Anyway that better than aluminium mirrors ,maybe better than silver-gilt mirror.

Jian

[steve-o]

Thanks Jian, I think I understand.
I plan on buying a set of yours when money allows..
Steve

[Pangolin]

Hi bill,
Do you remember that projector of PR-laser scanner in ILDA conference?
I think you already saw PR-laser scanner of lasershow.

Actually no. That projector did not have PR scanners in it as far as I know. Plus, one thing we must keep in mind is exactly WHO's software was running that projector...

Why intuition ?

I already explained my intiution. When someone has his masters degree and dozens of published papers, and spends 10 years working for one of the top scanner companies in the world, thereby having access to trade secrets of how to make scanners, and when the vast majority of scanners used by Chinese companies are made by PR, well, it just makes sense that they would be the best. That's my intuition. I have not yet received scanners and parts that they are sending, so I can test them and back-up my intuition. But until then, that's going to be my intuition.

By the way, I seem to recall that you were going to send me another scanner, or at least another rotor to replace the one that was shattered during testing of DT scanners. Have you sent it yet?

You will know which is best in future.:-)

Sure. The answer to that question is simple. Whoever has access to the best knowledge base of the details of scanners, plus access to the best machines and test equipment to manufacture and test scanners, plus access to the best actual parts (magnets, bearings, winding jigs, etc.), and finally whoever has the best quality control in place, will, by definition, be the best.


Bill

[jian725]

Actually no. That projector did not have PR scanners in it as far as I know. Plus, one thing we must keep in mind is exactly WHO's software was running that projector...

Oh,I sure that is PR-laser scanner .They using phoenix software and CNI blue laser.
You care what software they using.I care what scanner they using:-)

so I can test them and back-up my intuition. But until then, that's going to be my intuition.

Ahhh,let's see~~~~~~~

By the way, I seem to recall that you were going to send me another scanner, or at least another rotor to replace the one that was shattered during testing of DT scanners. Have you sent it yet?

I make the bigger order for the parts,(300 shafts,450PCB and 250 glavo's housing)so everything slow and the parts not enough.
That will get better at next week,everything enough.send to you ASAP.
Last at this month-end.

Sure. The answer to that question is simple. Whoever has access to the best knowledge base of the details of scanners, plus access to the best machines and test equipment to manufacture and test scanners, plus access to the best actual parts (magnets, bearings, winding jigs, etc.), and finally whoever has they best quality control in place, will, by definition, be the best.

Bill

All right.
BUT make an exception,you will find soon.:-)
Jian's company not a company,just a team.
No oscillograph etc...
But our team can creation the details :-)

Jian

[Pangolin]

Hi All,

I have done a bit more testing of the DT-40 PRO scanner. Some people might recall that David Zurcher was kind enough to send me his pair, since he also had an older DT-40 set he was using. During some initial testing, I actually shattered the rotor in one of the DT-40 PRO scanners (first time I ever shattered a rotor in my life!!), so I stopped testing right then.

Since I recently received some scanners from PR-Laser, I wanted to do some testing of DT-40 just for comparison purposes, so I used the remaining scanner for this purpose, being more careful this time not to shatter the rotor. I have produced a write-up with some of the results, which can be downloaded here:

http://www.pangolin.com/DT40Testing.pdf

Basically, the reader's digest of my initial testing results is that I like the output shaft thickness and mirror thickness of the PR-Laser scanners better than the DT-40 scanners. Since stiffness goes as the fourth power of a solid cylinder, and at least as the square of the thickness of a solid plank, the larger output shaft and thicker mirror is far better from a mechanical resonance standpoint. Also, PR-Laser scanners are tuned for 30K "from the factory" while DT scanners are tuned "higher". But as we have learned, the "higher" tuning does not do end-users any favors, as discussed in the past, and as seen in person by Photon Lexicon members at the last FLEM (and no doubt many meetings to come)...

I think Jian can improve his scanner by making the output shaft diameter thicker, and mirrors thicker, as discussed in several previous postings. Jian would also do his users good (some of whom are also Pangolin users) by a) getting an oscilloscope; b) learning how to use it to tune scanners; and c) tuning scanners to 30K.

If you want to go faster than 30K, it requires a different scanner design, which is why Cambridge has the model 6215 and PR has their model BL-40 (which may some day become the BL-60).

There are some aspects of DT scanners which I like better than PR-Laser scanners. I think Jian's X-Y mount is better, and certain electrical-connection-related things are better. But this will not be the case for long. PR-Laser has specifically sent me all of their scanners, and even pieces parts, and asked me to give them feedback. They will no doubt take my advice and quickly improve their products. The company who takes these recommendations and the recommendations of other users to heart, will no doubt produce the best scanners. If Jian and PR both take the advice from users, then both will produce very good scanners and everyone wins, which is of course the point of this whole exercise...

Best regards,

William Benner

[dave]

Interesting stuff Bill

[Zoof]

Tanks Bill, that is interesting.. I'm just curious now how Cambridge achieves that low rotor inertia with the ticker shaft... Or should the difference be accounted to the difference in calculated and specified inertia?

[jian725]

Hi Bill,

Hi All,
I think Jian can improve his scanner by making the output shaft diameter thicker, and mirrors thicker

William Benner

In fact,I was finished all parts,but I still not send to you,because waiting the 0.8mm mirror.Now the output shaft diameter is 1.95mm,and the gap is 0.8mm.
So I will send the rotor and the galvo when I get the 0.8mm mirror.

Greeting
Jian

[Pangolin]

Hi Jian,

Sounds good, but you don't have to "turn down" the output shaft to 1.95mm. The perfect shaft size for the inner journal of the bearing is 2mm. By "turning down" the shaft to 1.95 mm, you add an extra machining step, thereby increasing your costs of manufacture, and also involve a "tolerance" into the equation, which could possibly cause you to throw away parts that don't meet tolerance.

What all of the big scanner companies do these days is quite easy -- don't turn it down!! Just come straight out of the bearing journal with the full shaft size, unmodified. No extra machining steps, no extra tolerance, no wasted parts, no additional cost.

But what's more important than all of this is the increase in stiffness. Stiffness goes as the fourth power of the diameter for a solid cylinder. So it might seem that going from 1.95mm to 2mm wont do much (it's only a 2.6% increase). BUT, the stiffness is increased by (2 / 1.95) ^ 4 = 11% !! THAT is my point .

Best regards,

William Benner