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Mobius hack and initial test of IR illumination

Not long ago I have found a video about an fpv racing by pitch black and I really loved it.

I am thinking of a similar solution some time and the time for the project has finally come.

I intend to use the same gear as for daylight flying, except the fpv camera. For that, I want to use the Surveilzone low-lux Starlight cam. For the HD video recording, the good old Mobius will be used, slightly modified.

 

The requirements:

  • stealth quadcopter (no visible light emission at all)
  • 4-5 minutes flight time (racing)
  • IR sensitive HD recording (hacked Mobius)
  • IR sensitive CCD fpv camera (low lux rating)
  • additional IR illumination (IR laser)
  • illuminated area at least 60 degrees and 15m distance
  • ability to fly in pitch black conditions with moderate speed
  • ability to mount the IR gear to any 250-sized quadcopter

 

The Mobius hack

 

The first steps has already been made. I have started with the Mobius hack.

The idea was taken upon this article: http://publiclab.org/notes/cfastie/04-22-2014/mobius-ir-conversion

The only difference is that my approach was not as evasive, I have heated up the lens when unmounted and then pry out the IR filter without damaging it at all. Additionally, no debris fell on the glass lens at all so the optics remained clean.

The result can be seen on this first video:

No additional IR illumination was used.

 

The IR illuminator device

 

Now the biggest question is which one is the wavelength that the Mobius is most sensitive to. Unfortunately I could not find any relevant information on the net so I have to find it out by myself.

What I know is that for achieving the same illumination intensity, a 950nm wavelength LED needs approx. 3x more emitting power, than a 850nm LED, so a 850nm one would be a better choice.

For now, I made tests with the OSRAM’s LD271 950nm wavelength IR LEDs. The reason is simple, these could be obtained fast from a local sorce.

I have soldered 9 of them in series and gave them 120mA each (130mA is the max rating). The driver is a single LM317T IC.

I have to say I am not impressed by the light power at all. The chain should give around 100mW of output power total, according to the specs.

 

 

So I shot another comparison video, this time, illuminating the area nearby.

The result can be seen here:

 

It is clearly visible that the illuminating power of the 950nm LEDs are too weak. There are many 850nm LED boards available on the market but the best ones are big and heavy for my application.

Another option that is relatively small, lightweight but powerful enough is the usage of an IR laser. The beam can be unfocused to a decent amount of degrees. So I give it a try and get a handheld IR laser device soon.

Published in m250nvblog

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