Experiments in optics and image processing

After successfully mating a web cam with my microscopes (http://www.thingiverse.com/thing:216821) and telescope (https://www.youmagine.com/designs/web-cam-adapter-for-meade-telescope-eyepiece), I decided to design and print adapters to mount my Droid Turbo phone on the same scopes (https://www.youmagine.com/designs/microscope-adapter-for-droid-turbo-phone and https://www.youmagine.com/designs/droid-turbo-phone-to-telescope-adapter) so I could shoot higher resolution stills (21 Mp) and 1080p (and even 4k) video.   The telescope adapter fits over a Meade 32mm focal length Super Plössl eyepiece and provides about 47X magnification with the telescope.  I printed a similar adapter for my surgical microscope.

IMG_0995_crop

 

 

 

 

 

 

 

 

 

 

 

 

The telescope adapter firmly grips the phone and the eyepiece.

 

IMG_0993_crop

 

 

 

 

 

 

 

 

 

 

 

 

Initial tests were a little disappointing.  The combination of the phone’s camera and the telescope’s optics has significant pincushion distortion.  The image has only been mirrored L-R and scaled down (original is 21 Mp).  Note the lack of contrast (looking through 1/2 mile of humid air) and the curves in the power line and pole, and even the grass line:

pinch test original

 

 

 

 

 

 

 

 

 

A quick search found that the Gimp has built in transform tools to correct (or create) lens distortion.

 

gimp

 

 

 

 

 

 

 

 

It only took a couple minutes of messing around to get acceptable results.  Here’s the same image with the pincushion distortion corrected (whole image), contrast stretched and white balance corrected (rectangular area).  The pole, power line, and even the grass line now look straight.

pinch test corrected

 

 

 

 

 

 

 

 

 

And here’s the final image with all corrections and cropping applied:

final

 

 

 

 

 

 

 

 

 

 

Next step: photograph known square grids through the microscope and telescope and then create and save some preset corrections to apply with Gimp.

I wonder if something like this exists for video.  Hmmmmm…

 

 

 

 

 

Fix Your Symbols

BadSymbol

This Saturday I continued with the commissioning of my unified singing pumpkin controller. I got all the sub-systems working except for the power amplifier. In the picture above, on the left is the pumpkin controller. On the right is a (normal) Arduino amplifier shield using the same amp chip.  That shield works. If you look carefully you can see that the chip pins are mirrored between the two boards.

Mirroring pins is an innocent enough mistake. It happens to everyone once in a while. The problem is that I made the EXACT same mistake on the first round of that amplifier shield. (Notice the R2 on the right hand silk?) Apparently I fixed that problem manually without correcting my library symbol. That was many months ago and I forgot about it, thus resulting in a repeat of the same error on the unified pumpkin controller. Dumb mistake! It would have taken 10 mins at most to fix the symbol.

Don’t be like me, fix your symbols the moment you notice the mistake! You may not get back to it for a while and may not remember there was a problem.

 

Singing Pumpkin Controller

pumpkins pcb smallA few years ago I made animatronic singing pumpkins using an Arduino Uno, a Wave shield, a 16-channel servo/pwm controller, and some DC-DC power converters, all from Adafruit. I designed a single PCB that unified all of that and included a 15W amplifier. Today I completed assembling that board and began its commissioning. I used solder paste and a mylar stencil cut on our laser. Its the first time I have ever soldered a TSSOP package with no shorts.

Anyway, I managed to forget to bring a microSD card, but the program loaded into the AVR OK and is running. All the various power supplies are outputting the correct voltage.  6 volts for the servos, 5 volts for the AVR, and 3.3V for the microSD card and buffer chip. The amplifer gets the raw 12 volts. So, I’m hopeful that over the next week I’ll be able to bring the board completely online.

 

Member Badge Contest – Voting Open!

 

As announced in January, we had a Badge Contest that ran through April 21.  We had some great entries this year from our members.

Badge Contest Members

We had nine members show off their awesome badges at the meeting: Karen, Bill**2, Keith, Tom K., Kathy, Jon, Tom G., Brant & Carl

Now it’s the opportunity for everyone to vote and determine which badges they like the best!  Please view the badges and descriptions below, then click on the “VOTE HERE” link and select your favorite.

Several of the members submitted descriptions – please see them below.

Continue reading

Sometimes you gotta think outside the vase!

I found this nice vase on Thingiverse and printed it at 75% scale a couple weeks ago.

75% scale vase looks fine from this angle...

75% scale vase looks fine from this angle…

It came out pretty good except for the area near the bottom where it was overhanging.  3D printers don’t handle overhangs without support material very well.  I tried reslicing with support material added, but didn’t like the way it looked in either Cura or Slic3r so I didn’t try to print it again.

Overhang caused poor print quality for the first 6-8mm of the vase.

Overhang caused poor print quality for the first 6-8mm of the vase.

 

Then I tried printing it upside down- the overhang is much smaller.

100% scale vase printing upside down.

100% scale vase printing upside down.

About 12 hours later, here’s the result:  perfect!

The two vases, bottoms up- the 100% scale vase is perfect!

The two vases, bottoms up- the 100% scale vase is perfect!

 

 

 

 

 

 

 

 

 

 

 

 

 

CP2110 Breakout Board

cp2110_small

In following the internet chatter about the FTDI bricked-chip dust up some months ago I came across mention of a Silicon Labs USB-Serial chip, the CP2110, that worked a bit different. The device enumerates as a regular HID device and uses a standard OS driver rather than a manufacturer specific one. Being a HID device, there is no COM port. Instead you link a library into your application that knows how to engage the standard HID driver to talk to the chip in a serial-like fashion. In effect, this moves the driver from the OS to your application.

So I grabbed some of the chips and made up an OSHPark board that implemented the minimum passives and broke out the pins. Tonight, during Builder’s Night Out, I finally got around to soldering it up. The worst part about the CP2110 is that it is a 4mm x 4mm QFN with a 0.5mm pin pitch. I used the space’s 50W laser to make a solder paste stencil out of some of the giant roll of 3 mil mylar we have. My first go at it with one pass of the solder paste squeegee didn’t put down enough paste on the QFN and my second go with 3 or 4 passes in orthogonal directions put down too much solder paste.  There is probably a middle ground there.

Anyway, I used the space’s Zallus reflow toaster oven to reflow that second paste attempt and wound up with a number of the QFN pins shorted together. (I should have wiped the paste off and looked for that middle ground.) To fix the shorts I used the space’s hot air rework gun to pull the QFN chip off. That allowed me to solder wick the pads to a point free of shorts and then use the hot air gun once again to put the chip back. I over heated and burnt the tantalum caps and the LEDs in that rework process. So I used the hot air gun to remove those components and then hand soldered replacements back on to the board.

The moment of truth came when I plugged the freshly soldered board into my laptop’s USB port. I fully expected it to say “over current limit”, but to my delight it happily installed the HID driver! I’m looking forward to trying out the link library.

Classes and Collaboration lead to Happy Makers – Part 2

This a follow up post to this one. I’ll list a few more ongoing classes and collaborative build efforts at our space.

Ceramics 101

This class is required before working in the ceramics and pottery area. It teaches you the general rules of housekeeping and basics of materials used in this process. Class details here.

Polymer Clay Basics

This class is designed to give you an overview of the Polymer Clay process. This medium can be used to make a wide variety of small accessories and jewelry pieces.

Woodturning

Felisha has been introducing the addicting process of wood turning to many makers. The beginner class covers tools, sharpening, turning spindles, basic work holding strategies, and finishing. By the end of the class each person will have completed a bottle stopper!  Students actually learn on Felisha’s professional machine at Our Daily Salt. Class details here.

Trash to Cash

Tom had an ingenious scam idea to clean the makerspace. He shows you how to take a pile of junk and determine what has value and how to take it to the scrap yard and get cash for it! The money made from recycling is used to improve the space.

Keep your eyes open for more classes on the mailing list!

Annual Meeting Coming Up!

Ah…it’s that time of the year again – the time to pick new board members. This coming Tuesday, March 3rd, we’ll being nominations for the following positions:

  • President
  • Treasurer
  • Communications
  • Secretary
  • Operations Director

If you’re interested in giving back to this awesome community, please consider running for one of these positions or nominating someone you hate trust.

These (5) positions will be filled on March 17th and then we’ll begin nominations for the (2) At-Large board members. In summary, see this graphic courtesy of Brant.

borgmember