April 15th is tax day in the US, and of course this made me think about money. I started wondering if there were any features on paper currency that I could observe with my Foldscope 2.0! Read on to find out what I saw!
Figure 1. Picture of paper money from the USA from 1917 through 2017
(Photo Credit: Holly A. Stuart)
One Dollar Bills
I am fortunate enough to have a father in law who collects old currency. He recently gave me 1917 and 1934 dollar bills to look at under my Foldscope. The first thing I noticed on these bills was that George Washington’s face changed direction between 1917 and 1934. While studying his face with the 50X lens on my Foldscope 2.0, I was drawn to the magnified eyes of George Washington. The older bills were more challenging to view clearly because the bills were dirty with age, but the haunting stare was still evident!
Figure 2. Pictures of George Washington’s eyes on dollar bills from 1917 (top), 1934 (middle), and 2017 (bottom) viewed under a Foldscope 2.0 at 50X magnification
(Photo Credit: Holly A. Stuart)
Five Dollar Bill
In addition to the eyes of Abraham Lincoln (just as haunting as George Washington’s), I noticed that on the back of the bill, there was a replica of the Lincoln Memorial. When I looked at it under the microscope I was surprised to see that the Lincoln statue was visible inside the memorial. This was great - until I decided to zoom in on the face of the statue and it took on a more ominous appearance!
Figure 3. Pictures of Abraham Lincoln’s eyes viewed under a Foldscope 2.0 at 50X magnification (left), the Abraham Lincoln statue on the back of the five dollar bill at 50X (middle), and 50X plus 5X zoom on phone (right)
(Photo Credit: Holly A. Stuart)
Ten Dollar Bill
I found the eyes of Alexander Hamilton to be the most interesting things about the ten dollar bill. To me, the Foldscope view makes them look like the eyes of a raptor! With the 50X lens, you can also see the statue of Alexander Hamilton in front of the US Treasury building on the back of the bill.
Figure 4. Pictures of Alexander Hamilton’s eyes viewed under a Foldscope 2.0 at 50X magnification (left and middle) and Alexander Hamilton’s statue on the back of the ten dollar bill at 50X magnification (right)
(Photo Credit: Holly A. Stuart)
Twenty Dollar Bill
Again, the first thing I looked at on the twenty dollar bill were Andrew Jackson’s eyes. There is something powerful about thinking seeing your money “looking” at you through a Foldscope! I also observed the fine detail of the lantern that hangs above the entrance to the White House.
Figure 5. Pictures of Andrew Jackson’s eyes viewed under a Foldscope 2.0 at 50X magnification (left and middle) and White House lantern on the back of the twenty dollar bill at 50X magnification (right)
(Photo Credit: Holly A. Stuart)
All recent bills larger than one dollar have a textured surface. The Foldscope reveals the ridges on Andrew Jackson’s jacket (bottom row of pictures in the image below) that are not present on George Washington’s jacket from 1934 (top row of pictures in the image below). When I shifted the lighting on the twenty dollar bill, the ridges on the twenty dollar bill became more visibly prominent due to the angle of light hitting them.
Figure 6. Pictures showing the lack of texture on George Washington’s jacket on the 1934 one dollar bill viewed under a Foldscope 2.0 at 50X magnification (top left) and 50X plus 5X zoom on phone (top right) and the ridges of Andrew Jackson’s jacket on the twenty dollar bill at 50X magnification with direct lighting (bottom left) and angled lighting (bottom middle and right)
(Photo Credit: Holly A. Stuart)
One Hundred Dollar Bill
In addition to looking at the eyes of Benjamin Franklin, I also saw the crack in the liberty bell and the clock tower on the back of the bill. Interestingly, no one seems to know why the time is set at 10:30 (if anyone has any theories, please let me know!).
Figure 7. Pictures of Benjamin Franklin’s eyes (top), the crack in the liberty bell (bottom left), and the clock face (bottom right) viewed under a Foldscope 2.0 at 50X magnification
(Photo Credit: Holly A. Stuart)
The high value of a one hundred dollar bill has led to increased security features, one of which is color changing ink. When light hits this ink at different angles the color changes from copper to green. I achieved this effect with my Foldscope by shifting the LED light module slightly to the side (the images on the right side of the figure below).
Figure 8. Pictures of the color changing ink on the liberty bell (top) and the number 100 (bottom) viewed under a Foldscope 2.0 at 50X magnification
(Photo Credit: Holly A. Stuart)
The last interesting feature I found with US paper currency was the UV sensitive security strip that is embedded in every bill larger than one dollar. Each denomination has its own unique color that is revealed when the strip is placed under UV light. I used a blue/violet laser pointer to illuminate the five, ten, twenty, and one hundred dollar bills to see their respective colors.
Figure 9. Pictures of the security strip of $5, $10, $20, and $100 dollar bills (from left to right) viewed under a Foldscope 2.0 at 50X magnification with LED illumination (top) and UV illumination (bottom)
(Photo Credit: Holly A. Stuart)
Have you looked at money under a Foldscope 2.0? Use your Foldscope to dive into the microscopic world and find the beauty that is there waiting for you. Share your microscopic images and thoughts on the Microcosmos. Be sure to tag us on social media when you post the results of your explorations, creations, and discoveries! We love to see how Foldscopers around the world are using their Foldscopes in new and innovative ways!
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Sources:
https://www.secretservice.gov/sites/default/files/reports/2020-12/KnowYourMoney.pdf
https://www.uscurrency.gov/educational-materials/classrooms/currency-academy/science-lab
