Raspberry Pi Telescope

Telescope

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Last summer my dad and I built a Raspberry Pi based telescope based on the PiKon project. It was impressive that a basic understanding of optics, a curved mirror, and a lensless camera resulted in pictures of the moon!

Telescope

The idea behind the telescope seemed ingenious. Having taken physics the previous year I had been introduced to optics, but it didn't occur to me how easy it was to magnify an image. The goal of this project was to get clear pictures of the moon and to do that all we had to do was limit the light that entered our camera.

In an introduction to optics, one learns how to predict the image created by a series of lenses and mirrors by tracing the path of a photon traveling through such devices. The diagram shows this idea applied to a moon-telescope situation.

Diagram The light from the moon is assumed to be straight because of how far away it originated from

As the lunar photons enter the telescope, the parabolic mirror reflects them onto the image sensor placed at the mirror's focal point. Just like that, a magnified image appears!

Moon

After printing and fitting together the parts, two key challenges remained. How do we get the images from the Pi to a computer, and how do we aim the telescope?

Streaming

To get the Raspberry Pi to send back images I used VLC to create and receive a live stream. Besides capturing video, this made it easier to aim and focus the telescope. As the device had to be mobile I couldn't rely on WiFi to connect the computer and Pi, so I opted for a direct wired connection instead. Because the computer the Pi was being connected to didn't run a DHCP server, the Pi had to assign itself an IP on boot to make access via SSH simple. To do this, I found and followed this guide.

Once I could connect to the Pi, I installed VLC and started a live stream using the following commands.


sudo apt-get install vlc
sudo modprobe bcm2835-v4l2

cvlc v4l2:///dev/video0 --v4l2-width 1920 --v4l2-height 1080 --v4l2-chroma h264 --sout '#standard{access=http,mux=ts,dst=0.0.0.0:12345}'

The second command is required to setup the drivers for the camera to work with VLC. This fix was found on this StackOverflow post

After starting up the stream the first pictures appeared! Below you can see the image of a soccer ball on the laptop's screen. The soccer ball is by the left hand of the blurry person in the background.

Soccer

Scope

Once we could capture images from the telescope, we realized how difficult it was to focus the telescope on small objects. After spending half an hour angling the tube towards the moon with mediocre results, we decided a tripod was in order. While building a basic wood frame, we ran across a spotting scope. After attaching it with rubber bands and setting up the tripod-like holding device, we were able to get pictures like the one of the moon seen above!

Scope

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