June, 2019 Vibration Isolation Platform... Continued from previous page

vironments, such as vacuum cham- bers and cleanrooms, it is no wonder why every inch of space on bread- boards and platforms supporting a lab’s microscopy is fully utilized. Within these controlled envi-

ronments, floor and benchtop space is likewise optimized. And, mi- croscopy laboratories operating out- side of controlled environments fre- quently function in confined parame- ters, with little room to spare. Vibration isolation options for

the microscopy instrumentation in these environments has been limited to systems of several inches in height and higher, which for many can be too tall. This can make for tight working conditions and limit the in- strumentation that can be included on the breadboards and platforms. The ultra-thin, low-height CT-1

negative-stiffness vibration isolation tabletop platform, from Minus K Technology, can alleviate space con- straint issues. This unit is 2.25 in. (5.7 cm) in

height, yet delivers 0.5 Hz vertical natural frequency and 2 to 2.5 Hz hor- izontal natural frequencies. This is considerably more low-hertz vibration isolation performance when compared with air tables and active systems. Negative-stiffness isolators em-

ploy a unique and completely me- chanical design for low-frequency vi- bration isolation. They do not require electricity or compressed air. There are no motors, pumps or chambers, and no maintenance, because there is nothing to wear out. They operate purely in a passive mechanical mode. “In negative-stiffness vibration

isolation, vertical-motion isolation is provided by a stiff spring that sup- ports a weight load, combined with a negative-stiffness mechanism,” ex- plains Erik Runge, inventor of the technology enabling the CT-I isola- tion platform. “The net vertical stiff- ness is made very low, without affect- ing the static load-supporting capa- bility of the spring. Special flexures connected in series with the vertical- motion isolator enable the very low height, horizontal-motion isolation. The result is a compact passive isola- tor capable of low vertical and hori- zontal natural frequencies and high internal structural frequencies.” The CT-1 isolator achieves a

high level of isolation in multiple di- rections. It has the flexibility of cus- tom tailoring resonant frequencies vertically. The fact that the isolator operates entirely flexurally, and not translationally (which can exhibit stick-slip, frictional behavior), allows the isolator to operate in extremely low-vibration environments that would not be practical with top-per- formance air tables and other vibra- tion-mitigation technologies, such as active systems. “With the increased sensitivity

in instrumentation, particularly at the nanometer level, more precise vi- bration isolation technology than air tables was needed to deal with lower- hertz vibrations,” adds Runge. “Neg- ative-stiffness isolation, integral to the CT-1, was specifically designed to isolate these low-frequency perturba- tions.” Electronic-force cancellation sys -

tems (active isolation) use electronics to sense motion, and then add forces electronically to cancel out or prevent

the vibrations. “If sensitive mi- croscopy instrumentation can be iso- lated from vibrations, without having to deal with compressed air or elec- tricity, then it makes for a system that is simpler to install, easier to set up, and more reliable to operate and maintain over the long term,” ex- plains Runge. “It also makes for a sys- tem with considerable locational flexi- bility.” Reducing the height of the isola-

tor by several inches with the CT-1, not only optimizes critical space uti- lization, but also provides better er- gonomics for viewing through the eyepiece of the microscope. This is true not only for high-resolution mi- croscopy, but optical microscopy, as

well, as both rely on tabletop view- ing. As optical microscopes become more precise, the need for better vi- bration isolation becomes increasing- ly necessary.

Performance What the ultra-thin, low-height

CT-1 negative-stiffness isolator pro- vides is unique to the field of mi- croscopy — in particular, its trans- missibility. That is the vibration that transmits through the isolator as measured as a function of floor vibra- tions. The transmissibility of the CT- 1 is substantially improved over air and active isolation systems. When adjusted to 0.5 Hz verti- cal natural frequency, the CT-1 neg-

ative-stiffness isolator achieves ap- proximately 93 percent isolation effi- ciency at 2 Hz; 99 percent at 5 Hz; and 99.7 percent at 10 Hz. Negative-stiffness vibration iso-

lation systems have become a grow- ing choice for micro and nanotechnol- ogy microscopy applications. Not only are they a highly workable vi- bration solution, but they provide lo- cation flexibility and portability that other vibration isolation systems cannot. Contact: Minus K Technology,

Inc., 460 Hindry Avenue, Unit C, In- glewood, CA 90301 % 310-348-9656 fax: 310-348-9638 E-mail: Web: r

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