In the fields of semiconductors, precision optics, and materials science, nanoscale measurement has become a standard for judging product yield and R&D success or failure. However, many laboratories have purchased high-precision profilometers or atomic force microscopes, only to find that the measurement data is always fluctuating. At this point, the problem often lies not in the host itself, but in a very easily overlooked link - the tiny tremors on the ground. To truly stabilize nanoscale measurements, the key lies inModel Shock Absorber PerformanceThe advantages and disadvantages. A high-performance shock absorber platform can isolate the ubiquitous environmental noise from the outside world, allowing precision instruments to return to their original measurement characteristics.
Practical data shows that the vertical vibration amplitude of an uninsulated ordinary experimental bench in an office environment is usually between 0.5 micrometers and 1 micrometer. When attempting to perform surface morphology scanning with a resolution of less than 10 nanometers, this vibration will directly superimpose on the measurement signal, resulting in horizontal stripes and severe thickness data jumping in the image. At this point, the performance of the shock absorber platform directly determines whether the original data is useless or valuable.
Passive shock absorber platform: absorbs and isolates vibrations through elastic elements such as rubber pads, air springs, or mechanical springs. Its advantages lie in its simple structure, high reliability, and ability to effectively isolate high-frequency vibrations above 30Hz. For conventional optical microscopes or basic measurement tasks, the passive option in the performance of the shock absorber stage is sufficient, and its natural frequency can usually be designed between 3-5 Hz, which can attenuate vibrations above 30 Hz by more than 90%.
Active shock absorber platform: introduces sensors, controllers, and actuators. The piezoelectric or voice coil motor within the system can detect vibrations in real time and instantly generate a force of equal magnitude and opposite direction to counteract them. For environments that require nanoscale measurements in the low frequency range of 1-30Hz, an active damping platform is the only option. A high-quality active shock absorber platform, whose model shock absorber performance can effectively isolate vibrations starting from 0.5Hz, and still provide vibration attenuation of 10-15dB at extremely low frequencies of 1-2Hz.
Natural frequency: This is the core parameter of the passive damping platform. The lower the natural frequency, the lower the lower limit of the frequency at which effective isolation can begin. For example, an air floating shock absorber with a natural frequency of 2.5Hz means that it begins to have a significant isolation effect on vibrations above 5Hz (twice the natural frequency).
Vibration isolation efficiency: usually expressed as a percentage. Actual test data shows that high-level active shock absorbers can achieve over 90% isolation efficiency at 2Hz and over 95% efficiency at 10Hz. This means that a vibration velocity of originally 1 micron/second will be attenuated to below 50 nanometers/second when transmitted to the instrument end.
Transmittance curve: This is the most scientific way to express the performance of a shock absorber. A transmission rate less than 1 indicates vibration isolation effect. A real third-party testing report shows that the performance of a certain model of shock absorber platform is strictly controlled at a magnification of 5-8dB at the resonance point (usually 1-2.5Hz), and then the curve rapidly decreases, with a transmission rate below 0.2 at 5Hz.
Static stability: The shock absorber not only needs to isolate vibration, but also ensure that it will not drift slowly. The static repeatability of active shock absorbers is usually better than ± 50 nanometers, ensuring that long-term scanning does not produce baseline drift.
Viewing measured data: The supplier is required to provide the transmission rate curve and time-domain response graph measured by a third-party organization (such as a metrology institute) or using a laser vibrometer, rather than a simple ideal curve graph.
Pay attention to load capacity: The performance of the shock absorber is closely related to the load. Can its natural frequency and isolation efficiency still maintain their nominal values under full load conditions? A good shock absorber platform allows for a certain range of load changes (such as ± 10%) without significant performance degradation.
Conduct on-site testing: If conditions permit, portable vibration sensors (such as three-axis accelerometers) can be brought to the site. First, place the sensor on the ground, and then place it on the shock-absorbing platform. Compare the vibration amplitude differences between the two platforms at the main interference frequencies (such as 50, 100Hz power frequency, or a few Hz background low-frequency vibrations).
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