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Author Topic: LED arrays  (Read 30182 times)

mala

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Re: LED arrays
« Reply #15 on: May 08, 2014, 06:01:51 PM »
Hi there,

My LEDs are not being "powered up" at 0.5ms... what I said was the exposure time of the camera was 0.5ms.

My setup is rather more complex than just a PSU.

The LEDs each have their own driver, the LEDs are mounted in pairs on a custom heatsink, to which is also mounted a custom PCB which contains the two drivers and micro for control, with data and power connections.
Each LED requires approx 18Volt DC, this is supplied by a distro system (yet another custom PCB)
The DC power distro system is ultimately fed by 12 x 24VDC 13A power supplies in a rack system.

My LEDs are all individually controllable at very high speeds with either 8 or 16 bit dimming.

I'm sorry but that is as much detail as I can give at the moment.
Suffice to say this is not a quick and easy solution to make.

Cheers,
mala

Mfranquelo

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Re: LED arrays
« Reply #16 on: May 08, 2014, 06:23:22 PM »
Thank you Mala, i understand.

From what i see you're using continuous light with 0.5ms exposure then?
Wouldnt that light luminance (about 224k Lm) burn someone's open eyes taking account that light is continuous ?

Cheers,
Manuel.

mala

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Re: LED arrays
« Reply #17 on: May 08, 2014, 06:49:24 PM »
ok lets do some maths :)

320*700=224000   8) correct but we have filters in front of LEDs that ONLY transmit 40% of light,

40% of 224000 = 89600  ;) then sometimes we have some more of the same filter in front of cameras that again only transmit 40% of light.

40% of 89600 =35840  ??? where did all the light go !

These LEDs are not just in front of the subject, they are all around the subject.....

No we are not using "continous light" as such... that suggest you turn the LEDs on,walk away and just leave them on... that is not what we are doing...we can have the LEDs on full at 100% for very long periods of time and WITH the filters in place its is not too uncomfortable, but without the filters it would not be pleasant...fortunately as mentioned before all LEDs are dimmable.

Cheers,
mala

Mfranquelo

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Re: LED arrays
« Reply #18 on: May 12, 2014, 02:10:04 PM »
Ah true, i didnt take the polarizing filters into account  :-[
So thats 36k lumens for 0,5 ms exposure... May i ask which is the distance from light source to the subject in your rig ?

I might end up using capacitors. Rise up time is a problem with PSU.

mala

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Re: LED arrays
« Reply #19 on: October 10, 2014, 02:46:14 PM »
Here's a little sneak peak / teaser of the rig I mentioned previously

http://vimeo.com/m/107037919

 ;)

Mfranquelo

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Re: LED arrays
« Reply #20 on: October 11, 2014, 02:05:51 PM »
Its looking incredible mala, good job!  :)

Im building from scratch the tiniest flashes on the market (i hope!), to attach 30 low power flashes to my hemisphere, each of them will have a diffuse layer paper and polariser. The housing is (60mm diameter and 12 cm height), almost no recycle time.

I will post news soon at the end of the month.
( I tried the LED solution, but it didnt work for me  :-\)

Cheers,

mala

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Re: LED arrays
« Reply #21 on: November 18, 2014, 08:07:05 PM »
Here's another video of the rig that shows a little bit more  ;)

http://vimeo.com/112159110



@Mfarnquelo... how are the mini flash going ? they sound quite crazy but cool!

Mfranquelo

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Re: LED arrays
« Reply #22 on: November 19, 2014, 03:40:13 AM »
Thats incredibly cool mala! *Claps*
Great video-marketing as well  ;)

I hope to post something this coming weekend, we had some issues with the PCB suppliers (Newbury on UK)...
15 flashes are already mounted, 15 assembled and ready to be mounted. Its working wonders at the moment.
Meanwhile im playing with Canon SDK...

I hope to post some photos and a video!  :D

Speak soon!

Mfranquelo

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Re: LED arrays
« Reply #23 on: November 21, 2014, 02:27:39 PM »
Just a little preview! Haven t finished them yet  ::)

Cheers,
Manuel.

Mfranquelo

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Re: LED arrays
« Reply #24 on: November 26, 2014, 03:33:33 PM »
Here's a little update of how the prototype is progressing and updated results.

- No high pass filter applied
- No denoise
- Just how it came out of Agisoft.

Illumination is definitely improving scans! I am still on the process of comparing results taken at f16 and at f22.

Cheers,
Manuel.

Mfranquelo

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Re: LED arrays
« Reply #25 on: November 26, 2014, 03:34:29 PM »
Prototype updated.
Cheers!

mala

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Re: LED arrays
« Reply #26 on: November 26, 2014, 04:15:36 PM »
Hey Manuel,

The test result looks really good, well done !

The machine looks crazy , like it should be in space 8)
The little flashes look cool too.... get some nice connectors and throw away those choccy bloc (connection blocks) though ;)

Cheers,
mala

Mfranquelo

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Re: LED arrays
« Reply #27 on: November 26, 2014, 04:38:43 PM »
Indeed! Just told that to my colleague engineer. I've found some really cool and tiny pin-connectors female/male used for radio control cars power supply.

I've just applied the high pass and Lo Minimization denoise algorithm & basic AO. Everything is very subtle though, might not be noticeable at that resolution.

Thank you mala,
Cheers,
Manuel.

mala

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Re: LED arrays
« Reply #28 on: November 27, 2014, 02:12:19 PM »
Looks very good Manuel, Top work !  8)

3dmij

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Re: LED arrays
« Reply #29 on: December 01, 2014, 04:47:44 PM »
We use LED strips, powerful ones. 19watts per meter. We have 20 poles of 2 meter, so 760 watts of LED at about 90cm away from the person.

We have dimmed the LEDs a bit, not using PWM but decreasing the voltage from 24v to 19volt. This is to allow our projection system still to be able to project over the LED light.