3D Camera Using Fresnel Prisms for Compact Point Cloud Scanning
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Solution Overview
Problem
Existing surveying instruments capable of acquiring point cloud data and three-dimensional images have complex structures and are expensive, making them costly and difficult to implement.
Innovation Solution
A three-dimensional camera with a simplified structure, utilizing overlapping pairs of circular optical prisms for deflecting the distance measuring light, allowing for arbitrary scanning modes and integration of optical axis deflecting units, along with a posture detecting device for accurate measurements, reduces the size and weight while enabling easy acquisition of point cloud data and three-dimensional images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser scanner with deflecting mirrors is used to acquire point cloud data, then the measurement capability is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical deflecting mirror system with an optical axis deflecting unit composed of overlapping circular optical prisms. This substitution eliminates the need for complex mirror mechanisms while achieving the same light deflection function, thereby reducing device complexity and cost while maintaining point cloud data acquisition capability
Solution Approach 2:
The optical axis deflecting unit uses overlapping circular optical prisms that combine multiple optical elements into a unified structure. This composite optical system achieves efficient light deflection and scanning with simpler mechanics compared to traditional mirror-based systems
2Adaptability or versatility
If an image acquiring device is added to the laser scanner to capture images simultaneously, then the functionality is improved, but the device complexity and size increase
Solution Approach 1:
The patent integrates the image acquiring device with the optical axis deflecting unit, allowing both point cloud data acquisition and image capture to share the same optical path and deflecting mechanism. This merging reduces the overall device complexity compared to having separate systems
Solution Approach 2:
The optical axis deflecting unit serves dual functions: it deflects distance measuring light for point cloud acquisition and simultaneously directs light for image capture. This multi-functionality eliminates the need for separate deflection systems, reducing complexity while enhancing versatility
3Measurement precision
If traditional optical prisms are used in the optical axis deflecting unit, then the deflection function is achieved, but the size and weight increase
Solution Approach 1:
The patent transitions from traditional solid optical prisms to Fresnel prisms, which achieve the same light deflection function with significantly reduced thickness and weight. This parameter change in the prism structure maintains optical performance while reducing the weight of the moving optical unit
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
The solution provides a cost-effective and compact surveying instrument capable of acquiring point cloud data and three-dimensional images with high accuracy, even when carried or handheld, by simplifying the optical structure and using Fresnel prisms for reduced size and weight, and correcting measurements based on posture detection.
Implementation Method 1
an optical axis deflecting unit which deflects an optical axis of the distance measuring light; the optical axis deflecting unit includes a first optical prism and a second optical prism which are arranged in parallel and overlap each other
Implementation Method 2
the optical prisms which compose the second optical axis deflecting unit are Fresnel prisms
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
The invention provides a surveying instrument, which comprises a light emitting element for emitting a distance measuring light, a distance measuring light projecting unit for projecting the distance measuring light, a light receiving unit for receiving a reflected distance measuring light, a photodetection element for receiving the reflected distance measuring light and for producing a photodetection signal and a distance measuring unit for performing a distance measurement based on a light receiving result from the photodetection element, further comprises a first optical axis deflecting unit disposed on a projection optical axis of the distance measuring light for deflecting an optical axis of the distance measuring light at a deflection angle as required and in a direction as required, a second optical axis deflecting unit disposed on a light receiving optical axis for deflecting the reflected distance measuring light at the same deflection angle and in the same direction as the first optical axis deflecting unit and a projecting direction detecting unit for detecting a deflection angle and a deflecting direction by the first optical axis deflecting unit, wherein it is so arranged that the distance measuring light is projected through the first optical axis deflecting unit and the reflected distance measuring light is received by the photodetection element through the second optical axis deflecting unit and a three-dimensional data of a measuring point is obtained based on a distance measuring result of the distance measuring unit and a detection result of the projecting direction detecting unit.