Scepter Scientific Inc. Integrated Vision Technologies

Summary

An instrument was developed to modulate the cantilever of a microscope at high frequencies while monitoring changes in amplitude and phase to extract surface image information.

Since the instrument drives the cantilever directly with a magnetic field, the need to drive the cantilever mounting mechanism was eliminated, thus resulting in an increase in control. The resulting increase in control allows for smaller amplitudes, and therefore much smaller vertical forces on the sample.

The amplitude of the cantilever is amplified over a programmable range and is synchronously detected and converted to digital information with two16-bit analog-to-digital converters. The DSP then extracts phase and amplitude information while providing a programmable bandwidth and filter attenuation, so that a tradeoff of scanning speed versus noise level can be made.

The phase and amplitude information, which is the image, is converted back to 16-bit analog data for transfer to a computer for image capture.

An operator interface was provided for control of parameters such as gain of input stages, current drive of the cantilever, frequency of the cantilever oscillation, amplitude of the image signal, and bandwidth of the signals.

All parameters were stored in non-volatile FLASH memory for easy configuration of the instrument.

Features

Technologies

	Direct Digital Synthesis
	DSP Signal Processing
	Synchronous Detection of Low Level Signals
	Programmable Logic