General Scanning, Inc.

Hans Bengtsson

Mack J Schermer

Herman Deweerd

Brian Patrick Stokes

Markus Weber

Peter Honkanen

An optical scanning system uses a low-resolution scanning operation, to automatically adjust the sensitivity of the system. The system performs a low-resolution scanning operation by scanning a line, automatically and iteratively setting the levels of excitation signal power and detector gain, skipping a plurality of lines and scanning a next line, adjusting the levels as appropriate, skipping a plurality of lines and scanning a next line, and so forth. After the system sensitivities have been set, the calibrated system then scans all the lines of the sample to collect data. The calibrated system thus scans for the first time the lines that were skipped during the low resolution scanning operation.

Scanning system and method of operation for automatically setting

An optical scanning system includes a power meter that during calibration operations is illuminated by an attenuated excitation beam. The power meter measures optical power in the attenuated excitation beam at various index settings of a variable optical attenuator, and the system constructs a lookup table that relates incident excitation beam power to the index settings of the attenuator. The system then uses the table to select the appropriate setting for the attenuator in order to deliver to the sample an excitation beam of a specified optical power. The system calibrates the gain of a detector by redirecting, or reflecting, the excitation beam of known intensity to the detector. A photometric device in the detector produces a signal that is proportional to the intensity of the beam at various gain settings. The system then produces a lookup table that relates the gain settings to the actual gain of the detector, that is, to the ratio of the known incident power to the detector readings. The system thereafter uses the table to select the appropriate gain setting for data collection and/or to normalize the data. A beam splitter included in the system preferably discriminates between the light is passes and the light it redirects based on the spatial properties of the light. During calibration operations the excitation beam is reflected to the detector as wide diameter beams, which are passed through the beam splitter. During sample measurement operations the excitation beam is reflected by the sample as a narrow-diameter beam, which the beam splitter directs away from the detector.

Optical scanner calibration device

A bi-directional optical scanning system includes a spring-stiffened, taut-band mechanical subsystem that translates rotational motion of a servo-controlled actuator to translational (scan line or 'fast axis') motion of a sample relative to a stationary objective lens. A first taut steel band attaches to a first end of a shuttle that moves the sample over the fast axis. The band then wraps partially in one direction around a light-weight wheel that is rotated by the servo-controlled actuator. The second end of the band attaches to a pre-loaded spring that is, in turn, attached to the wheel. A second taut steel band wraps partially around the wheel in the opposite direction, with one end of the band attached to the wheel and the other end attached to a second end of the shuttle. When the wheel rotates in one direction, the first band pulls the shuttle, and thus, the sample, in the forward scan direction. When the wheel rotates in the opposite direction, the second band pulls the shuttle and the sample in the backward scan direction. As the wheel rotates, the first band fits into a slit in the second band where the two bands would otherwise overlap. Each band thus remains tightly wrapped around the wheel. The wrap angle associated with the overlay of the first band on the wheel is carefully chosen to ensure that the band does not slip relative to the wheel in response to forces associated with the acceleration of the sample or differences in thermal expansion of the wheel and the band. There is thus a known relationship between the rotational movement of the wheel and the translational movement of the sample even under varying environmental conditions.

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Sudbury, MA, United States of America

Hans Bengtsson