有人知道美元的防伪特征么？我要英文的，谢谢
參考答案:About the New $50 Notes
The new $50 note is the second note issued of the Series 2004 designs, which not only include subtle shades of color, but also highlight historical symbols of Americana. The new $50 note, which was issued in late 2004, includes shades of blue and red along with an image of a waving American flag and a metallic silver-blue star.
Security Features
The new $50 notes are safer, smarter and more secure: safer because they're harder to fake and easier to check; smarter to stay ahead of tech-savvy counterfeiters; more secure to protect the integrity of U.S. currency. Because security features are difficult for counterfeiters to reproduce well, they often do not try, hoping that cash-handlers and the public will not check their money.
Color-Shifting Ink: Look at the number "50" in the lower right corner on the face of the note. When you tilt the note up and down, the color-shifting ink changes from copper to green. The color shift is more dramatic in the redesigned notes, making it even easier for people to check their money.
Watermark: Hold the note up to the light and look for the watermark, or faint image, similar to the large portrait. The watermark is part of the paper itself and it can be seen from both sides of the note.
Security Thread: Hold the note up to the light and look for the security thread, or plastic strip, that is embedded in the paper and runs vertically to the right of the portrait. If you look closely, the words "USA 50" and a small flag are visible along the thread from both sides of the note. This thread glows yellow when held under an ultraviolet light.
Design Features
To stay ahead of currency counterfeiters, the U.S. will be introducing new currency designs every seven to ten years. Not only will many of these design updates add complexity to the note and make counterfeiting more difficult, other features will help the public, particularly those who are visually impaired, to tell denominations apart.
Symbols of Freedom: New symbols of freedom have been designed on the face of the $50 note to represent images of the American flag. The traditional stars and stripes of the United States flag are printed in blue and red behind the portrait of President Grant. A field of blue stars is located to the left of the portrait, while three red stripes are located to the right of the portrait. A small metallic silver-blue star is located on the lower right side of the portrait. The symbols of freedom will differ for each denomination.
Color: The most noticeable difference in the redesigned $50 note is the addition of subtle background colors of blue and red to both sides of the note. Also, small yellow 50s have been printed in the background on the back of the note. The Series 2004 notes mark the first time in modern American history that U.S. cash will include colors other than black and green. Different background colors are being used for the different denominations. This helps everyone to tell denominations apart.
Updated Portrait and Vignette: The oval borders and fine lines surrounding the portrait of President Grant on the face and the United States Capitol vignette on the back have been removed. The portrait has been moved up and shoulders have been extended into the border. Additional engraving details have been added to the vignette background.
Microprinting: Because they are so small, microprinted words are hard to replicate. The redesigned $50 note features microprinting on the face of the note in three areas: the words "FIFTY," "USA," and the numeral "50" can be found in two of the blue stars to the left of the portrait; the word "FIFTY" can be found repeated within both side borders of the note; and the words "THE UNITED STATES OF AMERICA" appear on President Ulysses S. Grant's collar, under his beard.
Low-Vision Feature: The large numeral "50" in the lower right corner on the back of the note is easy to read.
Federal Reserve Indicators: A universal seal to the left of the portrait represents the entire Federal Reserve System. A letter and number beneath the left serial number identifies the issuing Federal Reserve Bank.
Serial Numbers: The unique combination of eleven numbers and letters appears twice on the face of the note. On the new $50 note, the left serial number has shifted slightly to the right, compared with previous designs.
