Series PSD Arrangement for Extended Laser Detection Range
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Solution Overview
Problem
Current laser receivers for leveling applications face challenges with low saturation threshold, sensitivity issues in outdoor conditions, and limited detection range due to sunlight interference, making them unsuitable for commercial use in construction sites.
Innovation Solution
A light beam position detector using a series arrangement of Position Sensitive Devices (PSDs) with a readout circuitry that includes a variable interconnection and active resonator structure for improved backlight suppression and linearity, allowing for longer detection windows and increased sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single PSD is used for position detection, then the device structure is simple, but the detection range is limited due to low saturation threshold
Solution Approach 1:
The detection window is divided into multiple segments by using a series arrangement of multiple PSDs. Each PSD detects a portion of the light beam position, and their combined output provides an extended detection range while maintaining the simplicity of individual PSD structures.
2Device complexity
If photodiodes are used for position detection, then the device is simple, but sensitivity is low in outdoor conditions due to sunlight interference
Solution Approach 1:
The patent changes the operating parameters by using PSDs with higher saturation thresholds compared to conventional photodiodes. This parameter change enables the detector to maintain sensitivity and accuracy in outdoor conditions with sunlight interference, while the series arrangement further enhances the effective detection range.
3Length of stationary object
If the detection window is extended to cover wider distances, then the detection range increases, but linearity deteriorates
Solution Approach 1:
By segmenting the detection window into multiple PSDs arranged in series, each PSD maintains its linear response characteristics within its detection range. The combined output of these segmented PSDs preserves overall linearity across the extended detection window, solving the linearity deterioration problem that would occur with a single extended PSD.
Solution Approach 2:
The readout circuitry is designed to dynamically process signals from multiple PSDs, adjusting the interpretation of position based on which PSDs are active and their relative outputs. This dynamic processing maintains linearity across the extended detection range by compensating for the segmented nature of the detector array.
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 extends the detection range and sensitivity of laser receivers, enabling accurate position determination over a wide range of distances with improved linearity and robustness against sunlight interference, enhancing their usability in outdoor leveling applications.
Implementation Method 1
a first Position Sensitive Device (PSD) based on the lateral photoelectric effect, in particular with two - preferably opposed - output signals dependent on the striking position of the light beam
Data Source
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AI summary
The invention concerns a light beam position detector with a detection window, for detecting a position of a striking light beam within the detection window, which detection window comprises a first PSD based on the lateral photoelectric effect, in particular with two output signals dependent on the striking position of the light beam, and an electronic readout circuitry for the PSD. The detection window further comprises at least a second PSD based on the lateral photoelectric effect, being aligned in a geometrical line in succession with the first PSD, so that the first and the at least second PSD define the detection window.