Optical Comparators

16H Optical Comparator with 16″/400mm Screen

Dorsey’s most popular model of optical comparator, now featuring new look.

16H Optical Comparator

16H Optical Comparator Key Features:

• 16” high resolution vertical glass screen for optimum viewing of the erect profile image.
• Machined chart ring with recessed screen protects internal optics and facilitates the alignment of the screen to the optical axis.
• Large format vernier protractor with one minute graduations.
• Quick change single lens mount with choice of lenses: 10X, 20X, 25X, 31.25X, 50X, 62.5X, & 100X.
• Coated telecentric par focal optics.
• Choice of fiber optic or LED surface illumination.
• Nickel plated cast iron workstage 18” X 5” with universal dovetail slot.
• Stage travel is 10” x-axis and 6” y-axis and 2” focus.
• Crossed roller bearing table travel in all axes.
• X & Y axis 0.0005mm/.00002” linear scales have zero backlash and are mounted in the center of the stage movement for increased accuracy.
• The optics and workstage movements are mounted on cast granite composite base.
• Single hand quick release table allows for rapid travel and fine adjustment.
• The y-axis drive is mounted directly under the center of gravity for better weight distribution and increased accuracy. The handles are located for operator comfort during use.
• True par focal helix adjustment +/- 15 degrees with 5 minute vernier.

For more information please visit 16H Optical Comparator page at Dorsey Metrology website.

Pi, Greek letter (π), is the symbol for the ratio of the circumference of a circle to its diameter. Pi Day is celebrated by math enthusiasts around the world on March 14th. Pi = 3.1415926535…

With the use of computers, Pi has been calculated to over 1 trillion digits past the decimal. Pi is an irrational and transcendental number meaning it will continue infinitely without repeating. The symbol for pi was first used in 1706 by William Jones, but was popular after it was adopted by the Swiss mathematician Leonhard Euler in 1737.

π is an irrational number, which means that its value cannot be expressed exactly as a fraction m/n, where m and n are integers. Consequently, its decimal representation never ends or repeats. It is also a transcendental number, which implies, among other things, that no finite sequence of algebraic operations on integers (powers, roots, sums, etc.) can be equal to its value; proving this was a late achievement in mathematical history and a significant result of 19th century German mathematics. Throughout the history of mathematics, there has been much effort to determine π more accurately and to understand its nature; fascination with the number has even carried over into non-mathematical culture.

A Brief History of Pi

Ancient civilizations knew that there was a fixed ratio of circumference to diameter that was approximately equal to three. The Greeks refined the process and Archimedes is credited with the first theoretical calculation of Pi.

In 1761 Lambert proved that Pi was irrational, that is, that it can’t be written as a ratio of integer numbers.

In 1882 Lindeman proved that Pi was transcendental, that is, that Pi is not the root of any algebraic equation with rational coefficients. This discovery proved that you can’t “square a circle”, which was a problem that occupied many mathematicians up to that time.