The famous ๐ป๐บ ๐ฝ๐ฒ๐ฎ๐ธ ๐๐ผ ๐ฝ๐ฒ๐ฎ๐ธ ๐๐ฝ๐ฒ๐ฐ๐ถ๐ณ๐ถ๐ฐ๐ฎ๐๐ถ๐ผ๐ป๐is the criterion most commonly used by manufacturers because it is easy to communicate and broadly understandable.
This displacement is the local resultant of surrounding energy sources, expressed in acceleration.
Acceleration and displacement are linked by vibration frequency:
x(ฯ)=a(ฯ) /(omega^2)
However, few scientists think to ask the crucial question:โ๐ช๐ต๐ฒ๐ฟ๐ฒ ๐ถ๐ ๐๐ต๐ถ๐ ๐ฑ๐ถ๐๐ฝ๐น๐ฎ๐ฐ๐ฒ๐บ๐ฒ๐ป๐ ๐๐ฎ๐น๐๐ฒ ๐ฎ๐ฐ๐๐๐ฎ๐น๐น๐ ๐๐ฝ๐ฒ๐ฐ๐ถ๐ณ๐ถ๐ฒ๐ฑโโ๏ธ
The answer, hidden away on page 72 of the manual, asterisked at the bottom of the page in font size 5, is: ยซย ๐๐ถ๐๐ฝ๐น๐ฎ๐ฐ๐ฒ๐บ๐ฒ๐ป๐ ๐บ๐ฒ๐ฎ๐๐๐ฟ๐ฒ๐ฑ ๐ฎ๐ ๐ผ๐๐ฟ ๐ฐ๐ผ๐น๐ฑ ๐ณ๐ถ๐ป๐ด๐ฒ๐ฟย ยป
This is because on early optical cryostat architectures, the cryocooler was quite literally sitting on top of the optical table, while the acceleration it generates may be well damped at the sample holder, it is far less attenuated at other sensitive components on the optical table
Even if a cryostat supplier guarantees low-nm vibrations at the sample, the acceleration transmitted to the optical table can still impact other delicate elements:
๐ทAn ultra-stable optical cavity can be detuned by repeated micro-acceleration.
๐ทCCD detectors (yes, trapped ion scientists, we’re talking about you) are often mounted on flexible arms or supports, which can enter into resonance.
๐ท Vertical acceleration (z) on a mirror can cause angle modulations, affecting the optical path.
Most scientists pay๐ฒ๐ฒ for a high-quality vibration table to isolate their experiment from environmental noise sources.
Yet, in 99% of cases, the cryocooler is the largest mechanical noise source around. It is fundamentally backwards to put the noise source on top of the table you are trying to isolate. This energy is now quite literallyย isolatedย from leaving!
This is why most laboratories we go in that have a table-top system donโt float the table. Over time, users have found that they can achieve a net vibration performance improvement when the table is notย floating and hard sitting on the support legs.
If you think about it, this make very good sense as it allows the mechanical energy from the cryocooler to be inertially sunk to the floor/earth instead of being isolated on top of the table.
This comes at a compromise:
1) the expensive table they paid for is not being used
2) environmental noise source can now exited on-table equipment
3) the net experimental vibration performance is not as good as they expected or planned
Four9 has recognized that scientists ultimately care about the vibrations of whole experimental hardware chain, even if they donโt always consider this factor when first selecting a cryostat.
The ๐๐ผ๐๐ฟ๐ต cryostat has the best of both worlds.
Low sample vibrations ๐๐ก๐ low energy on the optical table
๐๐ผ๐๐ฟ๐ต innovative approach moves the cryo-cooler off the table into a tower, which is call the SideKick, where the bulk of the energy is shunted into the floor of the lab.
By anchoring it to the floor, vibrations are dissipated in a massive, rigid structure, reducing disturbances on the table.
Result:
๐ท๐น๐ฒ๐๐ ๐๐ถ๐ฏ๐ฟ๐ฎ๐๐ถ๐ผ๐ป ๐ป๐ผ๐ถ๐๐ฒ ๐ผ๐ป ๐๐ต๐ฒ ๐ผ๐ฝ๐๐ถ๐ฐ๐
๐ท๐ง๐ต๐ฒ ๐ผ๐ฝ๐๐ถ๐ฐ๐ฎ๐น ๐๐ฎ๐ฏ๐น๐ฒ ๐ฟ๐ฒ๐๐ฎ๐ถ๐ป๐ ๐ถ๐๐ ๐ฑ๐ฎ๐บ๐ฝ๐ถ๐ป๐ด ๐ฝ๐ฟ๐ผ๐ฝ๐ฒ๐ฟ๐๐ถ๐ฒ๐
Four9 is setting a new standard for optical cryostats, one that other manufacturers will inevitably have to followโto the great benefit of experimental scientists.
