Fiber Spatial Filter for Detector Saturation Reduction
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Solution Overview
Problem
Conventional spatial filter designs for laser range finders (LRFs) require multiple optical elements and mechanical stages, making them difficult to set up and maintain, and they occupy significant space, while internal light scattering from outgoing laser pulses saturates the detector, preventing detection of short-range objects.
Innovation Solution
Implementing a fiber-based spatial filter using an optical fiber to discriminate against light rays outside the field of view by propagating only light within the acceptance angle, eliminating the need for additional optics and mechanical alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional spatial filter designs are used, then detector saturation is reduced, but device complexity and space requirements increase
Solution Approach 1:
The patent extracts the essential spatial filtering function from the complex conventional system (multiple lenses, pinholes, mechanical stages) and implements it using a single optical fiber. The optical fiber alone performs the spatial filtering by its inherent numerical aperture properties, eliminating the need for additional optical elements and mechanical alignment components while maintaining the ability to reduce detector saturation.
Solution Approach 2:
The optical fiber serves multiple functions simultaneously: it acts as both the spatial filter and the light guide to the detector. This multi-functionality replaces the conventional system where separate components performed spatial filtering and light transmission, thereby reducing overall device complexity while achieving the same detector saturation reduction effect.
2Object-affected harmful factors
If conventional spatial filter designs are used, then detector saturation is reduced, but system volume increases
Solution Approach 1:
The patent removes the bulky mechanical stages and multiple optical elements from the conventional spatial filter design, retaining only the essential spatial filtering capability through the optical fiber. This extraction dramatically reduces the system volume while maintaining the ability to prevent detector saturation from scattered light.
3Object-affected harmful factors
If conventional spatial filter designs are used, then spatial filtering is achieved, but alignment precision is difficult to maintain
Solution Approach 1:
The optical fiber inherently maintains its alignment through its physical structure and mounting mechanism. The fiber's flexibility and the simple mounting approach allow it to self-accommodate to positional variations without requiring precision mechanical stages or complex alignment procedures, thereby maintaining spatial filtering effectiveness without sacrificing alignment precision.
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 fiber-based spatial filter reduces detector saturation, minimizes the system's size and weight, and maintains precise alignment under shock and temperature variations, ensuring effective detection of return signals from all ranges.
Implementation Method 1
The optical fiber propagates only light received at incident angles no greater than an acceptance angle
Implementation Method 2
The spatial filter includes a detector lens to focus the collimated optical signal at a focal point located at a focal length from the detector lens
Data Source
AI summary
An optical receiver comprises an optical detector, including a detection surface having a linear dimension, and a spatial filter. The spatial filter comprises a detector lens and an optical fiber. The detector lens focuses an optical signal at a focal point located at a focal length from the detector lens. A field of view of the optical detector is a function of the linear dimension of the detection surface and the focal length of the detector lens. The optical fiber has a first end mounted at the focal point of the detector lens to receive the optical signal, and a second end coupled to the optical detector. The optical fiber propagates only light received at incident angles no greater than an acceptance angle, which is sized relative to the field of view of the optical detector to spatially filter incident light outside the field of view of the optical detector.