Scanning Apparatus Spherical Cap Window Optical Distortion Correction
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Solution Overview
Problem
Laser scanners with spherical cap windows provide a wide field of view but introduce optical distortions in the 2-D image due to the curved window acting like a lens, which is undesirable in applications requiring accurate distance measurement.
Innovation Solution
The beam scanner is tilted or rotated about two perpendicular axes to define an intersecting point on the central axis of the window, and correcting arrangements such as lenses or curvature adjustments are used to minimize distortions, with options including shifting optics, inserting lenses, or providing a concave mirror to compensate for the spherical window's lens effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a spherical cap window is used to enable a wide field of view, then the field of view is improved, but optical distortions are introduced in the 2-D image
Solution Approach 1:
A beam scanner (mirror or prism) is introduced as an intermediary element between the laser source and the spherical cap window. This beam scanner directs the laser beam through the window while minimizing optical distortions by carefully positioning the beam path relative to the window's optical axis, thereby maintaining image accuracy while preserving the wide field of view provided by the spherical window
Solution Approach 2:
The patent adjusts optical parameters including the beam scanner's position, orientation, and scanning pattern to compensate for the lensing effect of the spherical cap window. By changing these parameters, the system maintains accurate 2-D imaging while utilizing the spherical window's wide field of view capability
2Measurement precision
If the beam scanner is positioned to minimize optical distortions, then image accuracy is improved, but the device complexity increases due to precise alignment requirements
Solution Approach 1:
The beam scanner is pre-positioned and pre-oriented relative to the spherical cap window during assembly to achieve optimal alignment before operation. This preliminary setup minimizes optical distortions and simplifies subsequent operation, as the alignment is established during manufacturing rather than requiring complex adjustment mechanisms during use
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes optical deviations and distortions, ensuring accurate 3-D imaging by maintaining the beam's coaxiality through the spherical cap window and improving the quality of data gathered by the scanner.
Implementation Method 1
the curved window acts, in some way, like a lens which, in cooperation with the beam scanner (mostly a mirror) might, however, introduce some optical distortions into the 2-D image
Implementation Method 2
beam scanning means for directing incident rays of radiation from a laser source to produce a pattern of a scanning beam
Data Source
AI summary
A scanning apparatus for use in a scanning optical system comprises a laser transmitter to produce a transmitter beam. This transmitter beam is deviated by a beam scanner, e.g. a tiltable mirror, to produce a pattern of a scanning beam. There are bearings which define first and second axes of rotation perpendicular to each other and intersecting each other in an intersecting point for allowing the beam scanner to scan. In front of the beam scanner is a window of transparent material in the shape of a spherical cap so as to define a central axis and a central point. The central axis intersects the intersecting point of the two other axes, and this common intersecting point coincides preferably with the central point of the sphere of the window.