Credit cards store data via localized polarization of the magnetic domains in the magnetic strip. The strip is actually composed of two or three separate "tracks." The tracks each contain the primary account number, service code, expiration date, and PIN information, so that the card can remain functional even if one of the tracks is damaged. For some reason tracks 1 and 3 have a higher recording density, so they put some additional information on those tracks (name, country code, etc.).
From a visual standpoint, the typical credit card mag strip is not particularly interesting. The magnetic domains can be visualized, but not with any equipment that is readily available to me. It's pretty much just a brown strip of tape. Luckily my Discover card has a hologram over the magnetic strip, so I got some cool images of that.
By the true definition of the word, these are not actually holograms, but everyone seems to call them that, so I guess I'll stick with it. I wish knew more about the printing process for these "holograms," but the 30 minutes of internet research I'm allowing myself to dedicate to this blog right now did not come up with anything I'm willing to be quoted on.
Fun Fact: This card is now cut up and in a trash can in Santa Monica where I was playing ultimate this weekend. I guess someone apparently tried to buy groceries with my information in Chicago on Saturday. Still not quite sure how that happened... Anyway here are a few of the more interesting images I got out of it before that.
Image magnifications are 10X, 10X, 33X, and 200X respectively. The scale bar in the lower right should give you an idea of how big the features are, the units are millimeters (mm) and micrometers (um). For reference human hair ranges from about 50 - 100 um.
Fun Fact: This card is now cut up and in a trash can in Santa Monica where I was playing ultimate this weekend. I guess someone apparently tried to buy groceries with my information in Chicago on Saturday. Still not quite sure how that happened... Anyway here are a few of the more interesting images I got out of it before that.
Image magnifications are 10X, 10X, 33X, and 200X respectively. The scale bar in the lower right should give you an idea of how big the features are, the units are millimeters (mm) and micrometers (um). For reference human hair ranges from about 50 - 100 um.
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ReplyDeleteI know this post is from 6 years back but I found it due to my searching for why my new Discover card has these "holigrams". Well...I found the patent for them on Google and the ARE called holograms and the patent dates all the way back to 1987! Have a look. Very interesting stuff!
ReplyDeletehttps://patents.google.com/patent/EP0286738A1/en
Follow up to my post about the patent for holograms in magnetic stripes in credit and debit cards. After further reading it looks like the patent was applied by US Banknote Company. Googling US Banknote Company comes up with ABCorp. ABCorp got their start with being the official engraver of the US Mint and the First Bank of the United States in 1795.
ReplyDelete