Surveying Optics With Triple-Reflection Prism for Wider Tracking
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Solution Overview
Problem
Conventional surveying instruments face limitations in trackable range and usability due to insufficient back focus and narrow angle of view, particularly when tracking fast-moving prisms at short distances.
Innovation Solution
A surveying instrument with a light receiving prism configured to internally reflect tracking light three times, using a first and second prism with specific surface configurations and coatings, and incorporating band pass filters to separate and receive distance and tracking light, allowing for a short focal distance lens and increased trackable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light receiving lens with a long focal distance is used to ensure back focus, then the back focus is sufficient, but the angle of view becomes small and the trackable range is narrow
Solution Approach 1:
The patent introduces a light receiving prism that redirects the optical path at approximately 90 degrees, changing the spatial dimension of light propagation. This allows the use of a short focal distance lens while maintaining sufficient back focus through geometric redirection rather than extending the optical axis length.
Solution Approach 2:
The patent changes the optical path configuration by introducing a light receiving prism with specific internal reflection surfaces. This geometric transformation allows the optical system to achieve the required back focus distance without using a long focal distance lens, thereby enlarging the angle of view and trackable range.
2Reliability
If a light receiving lens with a long focal distance is used to ensure back focus, then the back focus is sufficient, but the usability deteriorates at short distances and for fast-moving prisms
Solution Approach 1:
By redirecting the optical path through a light receiving prism, the system achieves sufficient back focus with a short focal distance lens. This dimensional change in light propagation enables the system to track fast-moving prisms and perform short-distance measurements effectively, significantly improving usability.
3Area of moving object
If the angle of view is enlarged to increase trackable range, then the trackable range is widened, but the back focus becomes insufficient
Solution Approach 1:
The light receiving prism redirects the optical path at approximately 90 degrees, allowing the system to use a short focal distance lens with a large angle of view while maintaining sufficient back focus. This geometric redirection decouples the relationship between angle of view and back focus distance.
4Area of moving object
If a short focal distance lens is used to enlarge angle of view, then the trackable range is widened, but the back focus becomes insufficient
Solution Approach 1:
The patent uses a light receiving prism to redirect the optical path, enabling the use of a short focal distance lens while achieving sufficient back focus. This allows the system to enjoy both the large angle of view and adequate back focus simultaneously.
Solution Approach 2:
The light receiving prism acts as an intermediary optical element that redirects light between the objective lens and the photodetector. This mediator allows the system to use a short focal distance lens while maintaining the required back focus distance through geometric path redirection.
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
Ensures a back focus for a short focal distance lens, enlarges the trackable range, improves distance measuring accuracy, and enhances usability by increasing the received light amount, especially for short-distance measurements.
Implementation Method 1
the light receiving prism is configured to internally reflect the reflected tracking light three times
Implementation Method 2
a separation surface is formed on a joined surface of the first prism and the second prism, the separation surface is configured to cause the reflected distance measuring light to be transmitted and to be received by the photodetector and to cause the reflected tracking light to be reflected and received by the tracking photodetector
Implementation Method 3
to deposit band pass filters on the first surface and the second surface, wherein the reflected tracking light having been transmitted through the first surface is incident into the second surface at an incident angle at which a transmittance is in the vicinity of 0%
Data Source
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AI summary
A surveying instrument comprises a distance measuring light projecting module (23) having a light emitter (28) which projects a distance measuring light (35) to an object, a distance measuring light receiving module (24) having a photodetector (39) which receives a reflected distance measuring light (49) from the object, a tracking light projecting module (25) having a tracking light emitter (53) which projects a tracking light (36) coaxially with the distance measuring light to the object, a tracking light receiving module (26) having a tracking photodetector which receives a reflected tracking light (51) from the object coaxially with the reflected distance measuring light, and an arithmetic control module which controls the distance measuring light projecting module and the tracking light projecting module, calculates a distance to the object based on a light receiving result of the reflected distance measuring light with respect to the photodetector, and calculates a position deviation between the object and a center of the tracking photodetector based on a light receiving position of the reflected tracking light with respect to the tracking photodetector, wherein the distance measuring light receiving module and the tracking light receiving module each have a light receiving prism, and the light receiving prism is configured to internally reflect the reflected tracking light three times.