1 minute understand DT50

[slicklasers]

What is scan speed and angle for the DT50BB with the mirrors for 7-8mm?

[jian725]

What is scan speed and angle for the DT50BB with the mirrors for 7-8mm?

There is no a standard answer this question.
What the speed at full angle?That depend on your shows and graph.
So we have a suggest:listen and touch.
If you make a show the scanner of noise not natural,set lower speed or angle.
At the same time touch the scanner mount,if just a little then just going,if very hot stop right now,don't let the galvo too hot.

DT50 alway lower heat than DT40,this is an important merit.

[Fearless]

What is the cost for DT50BB, and do you sell them directly?

[rns0504]

There is no a standard answer this question.
What the speed at full angle?That depend on your shows and graph.
So we have a suggest:listen and touch.
If you make a show the scanner of noise not natural,set lower speed or angle.
At the same time touch the scanner mount,if just a little then just going,if very hot stop right now,don't let the galvo too hot.

DT50 alway lower heat than DT40,this is an important merit.

How about a graph of maximum sinusoidal frequency vs angle for different apertures? This is a pretty standard graph that most manufacturers offer. Thanks!

[Fearless]

Hey Ryan,
I just got a scope and a function generator for tuning some Cambridge 6210H's that I bought off from fleabay. I got the manual from Cambridge for tuning the galvos--which have test points for the function generator and scope. I guess for looking at the tuning specs for other manufacturer's galvos and boards, that do not have testing points, I could input the a sinusoidal waveform via X+, X- inputs, but where would I put the scope probes for measuring output?
Thanks
Rick

[mixedgas]

Hey Ryan,
I just got a scope and a function generator for tuning some Cambridge 6210H's that I bought off from fleabay. I got the manual from Cambridge for tuning the galvos--which have test points for the function generator and scope. I guess for looking at the tuning specs for other manufacturer's galvos and boards, that do not have testing points, I could input the a sinusoidal waveform via X+, X- inputs, but where would I put the scope probes for measuring output?
Thanks
Rick

I've done my initial tuning that way for years. Cambridge used to give classes on how to do that method at LEMS and ILDA conferences. They also issued a handout on tuning to take with you. On the clone amps, you have to locate test point one and test point two by reverse engineering the position detector circuit. Most have the position sensor test point brought out and just labeled scan fail or test point on the board. Many amps simply do not have the test point.
~
THE SEVERE WARNING: WHILE CAMBRIDGE HAS YOU TUNE THE POSITION SENSOR OUTPUT TO 0.5V per DEGREE OR SIMILAR, THE CLONE AMPLIFIERS MAY NOT USE THIS CONVENIENT NUMBER AND MAY HAVE OTHER CALIBRATION FACTORS. NONE OF WHICH HAVE EVER BEEN PUBLISHED.
~
If you are tuning a cloned amplifier from scratch, accurately measure the volts per degree with their galvo before retuning the amp, or you may find yourself oscillating or unable to get a stable test pattern.

~
I've never seen the maker of a clone amplifier publish the Amplifier Volts Per Degree number, they either do not understand it or just do not wish to do it. Often they do change the resistor values to more or less suit their position sensor gain or different source LEDs/ detector PDs. So when you tune a clone or copy galvo amp from scratch that way, you can really dig yourself into a pit, if you mess with the position sensor initial setup per the Cambridge procedures. The slew rate change caused by adjusting the factor propagates through the whole servo loop.
~
For example, when I sold the modified amps for the 506s, the 506 has an awesome position sensor output voltage , we had to scale back the gains in the position sensor differential amplifier. Bill optimized that number in Orlando on the prototype,

If I'm messing with a clone/copy on the bench, I check the resistor values in the diff amp portion of the position sensor circuit. I also check the max position sensor LED current, as on some cloned amps, this can be quite high, and perhaps too high if I'm tuning a clone amp for a Cambridge or Scannermax Galvo. Often I'll buy a Chinese amp and use it with a US made Galvo, hence this little paragraph.
~
Another hint, the Cambridge tuning in the manual is usually for maximum speed, when I do that, I have actually detune the amp 10-20% and then go find the ILDA tuning by the test pattern. You will possibly have to back off on servo gain and derivative once you do the factory "square wave" tuning, in order to get the ILDA pattern into shape.
~

~
As for the signal generator, you can either build a differential sender circuit (Attached fragment in PNG) Link to full, original, ancient copy of ILDA document: http://photonlexicon.com/forums/atta...8&d=1390537157.


~
Or just ground the amp's Neg input and use the Pos input with the signal generator, remembering that you may now need double the input voltage for the same scan angle. If you build the "official" diff driver circuit, add a 100K or 1 Meg to ground on its input to pull its output to a weak zero voltage in case you disconnect the signal generator.
~

Steve

[mixedgas]

If I have time this weekend I'll show how to measure the 3 dB down sine response for poor Jian, who's post/thread has been hijacked many times now...

Steve

[rns0504]

Most max 60 degress,DT50W max 85 degress for 5mm beam.
http://www.dtelectronic.cn/production.asp?ArticleID=54

I am curious how a 8.5mm wide mirror can scan a beam 85 degrees as you say.

My math tells me that the mirror would need to be 12.41mm wide to be able to do this

My math also tells me that a 8.5mm wide mirror can only move a 5mm beam by a maximum of 18 degrees optical "forward", for a total of a 36 degree symmetrical scan angle.

Can you please clarify this for me - with math and facts and such? Thanks

[jian725]

I am curious how a 8.5mm wide mirror can scan a beam 85 degrees as you say.

My math tells me that the mirror would need to be 12.41mm wide to be able to do this

My math also tells me that a 8.5mm wide mirror can only move a 5mm beam by a maximum of 18 degrees optical "forward", for a total of a 36 degree symmetrical scan angle.

Can you please clarify this for me - with math and facts and such? Thanks

Who say scann at 85 degress all of beam on the mirror?

For 5mm beam is when the scanner working not max angle,maybe <50 degress.
When >50 degress maybe lose 40%,but still working.Like you show a 85 degress circle you can
see a complete circle,but don't need care how many power at the edge.

But if you use a max 60 degress DT50 when you show 85% degress circle you see a NOT complete circle.
Laser out of the mirrors.
That is the different.

[rns0504]

I mean, the words

DT50W max 85 degress for 5mm beam.

Kind of implies that it can scan a 5mm beam through 85 degrees...

See when I spec a mirror set, 4.5mm at 60 degrees, it will move a 4.5mm beam through a full 60 degrees optical without any losses. If I say 10mm at 40 degrees, it will scan a full 10mm beam through a full 40 degrees without any losses. Thats how to accurately spec something, and the honest way as well.

But maybe instead I should just call it a 10mm 100 degrees mirror set, im sure some part of the mirror will capture some part of the beam... seems to be the logic being used here.

I digress.