Research in the So Lab

Fast XY Scanning Stage for Multiphoton Microscopy

Investigators: Hyuk-Sang Kwon, Ki Hean Kim, Ruby Pai & Peter So.

The design of the high precision XY stage was composed of two phases.

The first phase dealt with the design of a mechanical structure that ensured meeting the functional requirements.

The second phase focused on actuating the force along the two axes and on developing the appropriate sensor system and control method. Using the proper control, requirements can be achieved.

Functional Requirements
1) Stage geometry: has to fit the current XXX microscope
2) Coarse Translation: X direction in 3.5"
3) Fine Translation for imaging: X direction in 1", Y in 1"
4) Resolution of 1 micron in each direction.
5) Speed for coarse translation: 10 cm / 5 sec
6) Speed for fine translation: 2 mm / 0.02 sec
7) Sample load: up to 10 g
8) Settling time (98%): <1 sec for coarse translation
9) Settling time (98%): <0.02 sec for fine translation
10) Stiffness: enough to operate various cutting motion such as milling and vibratoming.

Mechanical structure design of the XY stage is designed in order to fit the current Olympus microscope. For sample positioning, the stage was designed with considerations of four major requirements defined earlier: proper travel range, small parasitic motion, and short transient time response. The stage must have a central aperture of about 2" diameter for white light illumination. Therefore, a custom designed stage was necessary. For less friction and higher stiffness, air bearing from Newway Precision is chosen. Coefficient of friction for it is .00001. Stiffness for air bearing is 2,000,000 lb/in. With this configuration, the expected air gap change is less than 2 micron. All components were bolted together using various size threaded screws and positioned with clearance holes. Linear Encoder from MicroE Systems is selected for its high resolution of 0.078 micron and its compactness. Linear motor from Aerotech is chosen for actuation for its high power and less friction.