— Automatic Optical Alignment for AFM

Adviser: Li-Chen Fu

The Project on Micro Manipulation Contest

Team Members:S. K. Hung, C. F. Tsai,Y. P. Shyu, D. J. Tzou

2003 Sep. 19

1. Introduction2. A Novel Optical Design for AFM3. The Profile of This Project

Outlines

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1. Introduction

Typical AFM Block Diagram

Question: Move the Sample or Move the Probe?

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Scanning Sample Type (move the sample / fix the probe)

simple detective optical arrangementlimited sample size / mass

Scanning Probe Type (move the probe / fix the sample)

unlimited sample size / massdetective optical head is too massive (700g) to movetracking laser path is hard to implement (nm scale tracking error)

Scanning Sample Type v.s. Scanning Probe Type

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Scanning Sample Type v.s. Scanning Probe Type

Detective Optical Head

4 DOFs to adjust!→ complex mechanism embedded→ massive (700g)→ limited scanning frequency

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Scanning Sample Scanning Probe

Sample Size small large

Optical Complexity

simple complex

Image Resolution

better worse

Response slow fast

Scanning Sample Type v.s. Scanning Probe Type

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Question:Move the Sample or Move the Probe?Answer: Move the Sample in Horizontal Directions (x, y)

and Move the Probe in the Vertical Direction (z).

Reason: 1. Horizontal scanning motion is slow (<10Hz) a massive sample is OK 2. Vertical tracking motion is fast (>1000Hz) a light probe is OK

Remark: I propose a novel optical design to cause the detective laser spot to track the probe’s vertical motion.

Scanning Sample Type v.s. Scanning Probe Type

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2. A Novel Optical Design for AFM

1. Detective Laser Spot Tracking (novel)2. Traditional Optical Microscope3. Combination

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Detective Laser Spot Tracking

The two lenses can move relatively

KEY: Keep the optical path parallel

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Traditional Optical Microscope

m100

Magnitude = f2 / f1

The two lenses can move relatively

CCD camera

KEY: Keep the optical path parallel

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Novel AFM + Traditional Optical Microscope

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3. The Profile of This Project

Integrating AFM with a traditional optical microscope

Automatic tip exchange (2-dof) and optical alignment (4-dof)

Combining advantages of both scanning types(scanning sample type and scanning probe type)

The Targets of This Projects12/17

D/A card 6208 with control software

Automation Flow Diagram

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protection

lens set

probe

magnet

bimorph

piezo z-scanner

base

steel plate

Z-Scanner Mechanism with Lens

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z

x

y

z

Robot Mechanism

Coil

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S. K. Hung C. F. TsaiY. P. Shyu D. J. Tzou

Optical Design Robot IP Integrationpreliminary exp. mechanical design Hardware Setup Servo Control

mechanical design motor driving Edge Finding System ProgramAFM setup control program

Human Resources

Any Comment Is Appreciated!

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