Tutorial
Selection of Vibration Isolators
Masaki Hosoda
Dec. 7, 2009
OPTI 521
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Contents
„
„
„
Purpose
Motivation
Two types of Vibration Isolation
„
„
„
Passive Vibration Isolation
Active Vibration Isolation
Summary
Dec. 7, 2009
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Purpose of this presentation
„
Let you know
„
„
„
how vibration isolation works
how to select vibration isolators
examples of application
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Motivation
„
Vibration Isolation is important for
„
„
Optical measurements
Optical fabricatons
From TMC, STACIS
From Zygo, GPI series
http://www.techmfg.com/appnotes/SematechAppnote.htm
http://www.zygo.com/?/met/interferometers/gpi/flashphase/
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Two types of
Vibration Isolation
„
Passive Vibration Isolation
„
„
„
Mass, Spring, and Damper
Can isolate high frequency (5Hz~)
Active Vibration Isolation
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„
Mass, Spring, Damper, and Feedback or Feedforward
Can isolate low frequency (~5Hz)+ high frequency
Dec. 7, 2009
From TOKKYOKIKI
http://www.tokkyokiki.co.jp/technology/technology_a.html
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Passive Vibration Isolation
1
fn =
2π
2
⎛
⎛
⎞
k
C ⎞
⎜1 − ⎜
⎟
⎟
m ⎜ ⎝ CC ⎠ ⎟
⎝
⎠
C/CC is Critical damping ratio CR
•You want fd/fn
•fd is defined.
•Then fn should
•C/CC should
•k should
•m should
Dec. 7, 2009
Advantage
•Low cost
Drawback
•Amplification Region
•Not stable.
OPTI
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From Barry
isolators
selection guide.pdf
6
Selection of
Passive Vibration Isolator
„
„
Determine fd (Disturbing frequency)
and Min. fn
fn =
fd
2
Use direct measurement
or Rule of Thumb
Dec. 7, 2009
From Yoder
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Example of
Passive Vibration Isolator
From THORLAB
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Active Vibration Isolation
Feedback
Feedback + Feedforward
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Advantage
•No Amplification Region
Drawback
•Cost
•algorism
•Need reference
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Selection of
Active Vibration Isolator
Advantage
Drawback
Feedback
durable for unexpected
disturbance
Slow response
Feedforward
+ Feedback
Fast response
Need correct reference
Need correct model
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Example of
Active Vibrartion Isolator
Lithography Stage by Canon
Vibration isolation platform
1. Pressure (Force)
2. Position
3. Velocity
S. Wakui, “Active vibration isolator, exposure apparatus, exposure method and device manufacturing method”
Dec.
7, 2009
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United States Patent
6,286,644
B1 (2001)
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Summary
„
Two types of Vibration Isolation
„
Passive Vibration Isolation
„
„
„
Low cost, works for high frequency
Have amplification region, Not stable
Active Vibration Isolation
„
„
Dec. 7, 2009
No amplification region, works for low freq.
Need Algorism and reference
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