Case Studies
1. Measurement Details
- Measurement Date
September 5, 2017 - Measurement Devices
1. LAN-XI Data Acquisition Hardware
– Brüel & Kjæ r 3050-A-040 (Serial Number: 3050-111438)
2. Data Analysis Software
– Brüel & Kjæ r PULSE LAB SHOP 22
3. Sensors
– PCB Accelerometer
– Model: 393B05 (Serial Number: 48995, 40626) - Measurement Location
1st Floor - Measurement Setup
Bandwidth: 0 – 100 Hz
Lines: 400
Window: Hanning
Averaging: Fast Fourier Transform Spectrum Averaging
Amplitude Units: m/s2
Spectral Unit: RMS
2. Equipment Information
- Manufacturer
Thermofisher Scientific - Model
Apero 2 - Floor Vibration Specification
Disturbances due to vibrations and acoustics play a significant role. Vibration levels can be limited by proper building design in combination with vibration isolated platforms.
The floor vibrations are defined by the vibration criterion (VC) curves, by Ungar and Gordon. VC levels are defined as rms speed values, integrated over one
third octave bands. The VC-curves are to be used as guidelines only, the final room behavior with regard to vibrations will be determined during a site survey performed by trained FEI personnel using FEI’s Site Evaluation Tool. Depending the purpose of the microscope, time constant is involved in the vibration characteristics. VC Curves Guidelines provided by the VC-curves can be interpreted as described below.
The table lists applicable VC-curves for certain direction and system. In general VC-F should be achieved.
3. Vibration Isolation System Information
Model: DVIA-MB1000
| Platform Dimensions | 1140 x 910 x 224 mm | |
| Load Capacity | 500 - 1700 kg | |
| Actuator | Electromagnetic Actuator | |
| Maximum Actuator Force | Vertical: 40N, Horizontal: 20 N | |
| Degrees of Freedom | 6 degrees | |
| Active Isolation Range | 0.5 - 100 Hz | |
| Vibration Isolation at 2 Hz | ≥90% | |
| Vibration Isolation at 10 Hz | ≥99% | |
| Input Voltage (V) | AC100 - 240V / 50 - 60 Hz / 1A | |
| Power Consumption (W) | Maximum 110W, <50 W in normal operation | |
| Operating Range | Temperature (°C) | 5 - 50 °C |
| Humidity (%) | 20 - 90% | |
| Required Air Pressure | ≥ 0.5 MPa (5 bar) | |
4. Installation Photos
5. Summary
| Floor Vibration Specification | |||
|---|---|---|---|
| Frequency Range | 1 - 80 Hz | ||
| Floor Vibration Specification | VC-F | ||
| Measurement Direction | Z axis (Vertical) | X axis (Left to Right) | Y axis (Front to Back) |
| Floor Vibration | Fail | Fail | Fail |
| Vibration On Active Vibration Isolation System | Pass | Pass | Pass |
6. Results
Z-axis (Vertical)
The measured vertical floor vibration exceeded the floor vibration specification at 5 Hz, 10 Hz, 20 Hz to 80 Hz. The
active vibration isolation system reduced the vertical floor vibration from VC-C to VC-G.
X-axis (Left to Right)
The measured vertical floor vibration exceeded the floor vibration specification at 5 Hz, 10 Hz, 20 Hz to 80 Hz. The
active vibration isolation system reduced the vertical floor vibration from VC-C to VC-G.
Y-axis (Front to Back)
The measured Y-axis floor vibration exceeded the floor vibration specification at 2.5 Hz.
The active vibration isolation system reduced the Y-axis floor vibration from VC-E to VC-G.
7. Results – Vibration Isolation Effects on Imaging
Active Vibration Isolation Off
HV:30.00 kV
Mag: 800 000 x
Linewidth: 100 nm
Active Vibration Isolation On
HV:30.00 kV
Mag: 800 000 x
Linewidth: 100 nm
Active Vibration Isolation Off
HV:30.00 kV
Mag: 800 000 x
Linewidth: 100 nm
Active Vibration Isolation On
HV:30.00 kV
Mag: 800 000 x
Linewidth: 100 nm
8. Reference
Generic Vibration Criteria
| Criterion Curve | Description | Amplitude1) μm/s (in/s) | Detail Size2) μm |
|---|---|---|---|
| Workshop (ISO) | Distinctly perceptible vibration, Appropriate to workshops and non-sensitive areas. | 800 (32,000) | N/A |
| Office (ISO) | Perceptible vibration. Appropriate to offices and non-sensitive areas. | 400 (16,000) | N/A |
| Residential Area (ISO) | Barely perceptible vibration. Appropriate to sleep areas in most instances. Usually adequate for computer equipment, hospital recovery rooms, semiconductor probe test equipment, and microscopes less than 40x. | 200 (8,000) | 75 |
| Operating Theatre (ISO) | Vibration not perceptible. Suitable in most instances for surgical suites, microscopes to 100x and for other equipment of low sensitivity. | 100 (4,000) | 25 |
| VC-A | Adequate in most instances for optical microscopes to 400x, microbalances, optical balances, proximity and projection aligners, etc. | 50 (2,000) | 8 |
| VC-B | Appropriate for inspection and lithography equipment (including steppers) to 3pm line widths. | 25 (1,000) | 3 |
| VC-C | Appropriate standard for optical microscopes to 1000x, lithography and inspection equipment (including moderately sensitive electron microscopes) to 1μm detail size, TFT-LCD stepper/scanner processes. | 12.5 (500) | 1-3 |
| VC-D | Suitable in most instances for demanding equipment, including many electron microscopes (SEMs and TEMs) and E-Beam systems. | 6.25 (250) | 0.1-0.3 |
| VC-E | A challenging criterion to achieve. Assumed to be adequate for the most demanding of sensitive systems including long path, laser-based, small target systems, E-Beam lithography systems working at nanometer scales, and other systems requiring extraordinary dynamic stability. | 3.12 (125) | <0.1 |
| VC-F | Appropriate for extremely quite research spaces; generally difficult to achieve in most instances, especially cleanrooms. Not recommended for use as a design criterion, only for evaluation. | 1.56(62.5) | N/A |
| VC-G | Appropriate for extremely quite research spaces; generally difficult to achieve in most instances, especially cleanrooms. Not recommended for use as a design criterion, only for evaluation. | 0.78(31.3) | N/A |
- As measured in one-third octave bands of frequency over the frequency 8 to 80 Hz (VC-A and VC-B) or 1 to 80 Hz (VC-C through VC-G).
- The detail size refers to line width in the case of microelectronics fabrication, the particle (cell) size in the case of medical and pharmaceutical research, etc, It is not relevant to imaging associated with probe technologies, AFMs, and nanotechnology.
The information given in this table is for guidance only. In most instances, it is recommended that the advice of someone knowledgeable about applications and vibration requirements of the equipment and processes be sought.