1. Positioning/ alignment device for ophthalmic scanning laser systems
Thomas Fleming
Dan Frost
Vidhya Raju
William Stanford
Client: Carol Rasmussen
Advisor: Dr. Tom Yen

3. Problem Statement and Specifications
Main problem: restricted motion
Patients may not be responsive to instructions
Need following degrees of motion
Vertical
Horizontal
Rotational
Tilt, if possible

4. Design Constraints Height, angle and rotation
Distance from patient’s eye
Resolution of movement
Loading (weight of machine 83 lbs)
Ergonomic interface with patient and technologist
Animals and humans

5. Design 1 – Overhead Arm Pros Movement in x, y and z directions
Tilt and rotation possible
Good coarse adjustment
Cons
Expensive to build or buy
Large, bulky
No fine adjustment

6. Design 2 Precision Frelon Plain-Bearing Slides with Lead Screw
Pros
Precise adjustments
Can withstand five times load required
User friendly controls
Cons
Expensive to buy all parts
Difficult to assemble for all movements
Torque considerations

7. Design 3 Fine-Adjust Cross-Slide Tables
Pros
Precise adjustments
Can withstand two times load required
Hands provide easy adjustment
Cons
No tilt option
Requires modification for rotation
Heavy

8. Design Matrix Design Constraints Weight Overhead Arm
Precision Frelon Plain-Bearing Slides with Lead Screw
Fine-Adjust Cross-Slide Tables
Degrees of Motion 20 19 17
Ergonomics 15 3 10 13
Load Bearing 5
Ease of Rotation 7
Precision 2 14
Cost
Total
100 44 72 90

9. Design Decision: Fine-adjust Cross Slide Table
Relatively low cost ($285 of $1000 budgeted)
Allows us to focus on rotation options
Could be modified for electromechanical control

10. Future Work: Rotation & User Interface
Rotation about a fixed point at the front edge
Ball casters
Fix to the edge of the table
Current interface has multiple dials
Reduce to a single control interface