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

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 http://cache.daylife.com/imageserve/0bS97VJbYyfaB/610x.jpg

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

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

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 http://www.mcmaster.com/

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 http://www.mcmaster.com/

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

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 http://www.palmgren.com

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 http://www.chproducts.com http://www.mcmaster.com/