Concave Bandpass Filter for Ambient-Light-Resistant Ranging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In portable electronic equipment, light receiving modules require a bandpass filter with a wider bandwidth to accommodate varying chief ray angles, leading to increased disturbance from ambient light.
Innovation Solution
A distance measuring system with a light receiving module that incorporates a bandpass filter with a concave-shaped light incident surface, allowing for a narrower bandwidth while reducing disturbance from ambient light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bandpass filter with a wider bandwidth is used to accommodate varying chief ray angles in portable electronic equipment, then the filter can receive target light at the center and periphery of the light receiving unit, but the influence of disturbance light increases
Solution Approach 1:
The bandpass filter is designed with a concave-shaped light incident surface instead of a flat surface. This curvature allows the filter to accommodate varying chief ray angles from the center to the periphery of the light receiving unit while maintaining a narrow bandwidth, thereby reducing the influence of disturbance light while still receiving target light effectively across the entire imaging element.
2Object-affected harmful factors
If a narrow bandwidth is set for the bandpass filter to reduce disturbance light influence, then the filter can reject ambient light effectively, but it becomes difficult to receive target light at the periphery with varying incident angles
Solution Approach 1:
The concave-shaped light incident surface of the bandpass filter is specifically designed to match the angular distribution of incoming light from the optical system. This curvature enables the filter to maintain a narrow bandwidth for effective disturbance light rejection while still accepting target light across the full angular range from the center to the periphery of the light receiving unit.
3Adaptability or versatility
If the bandwidth of the bandpass filter is widened to accommodate pupil correction, then the filter can work with chief ray angle differences, but measurement precision deteriorates due to increased disturbance light
Solution Approach 1:
The concave-shaped light incident surface enables the bandpass filter to maintain a narrow bandwidth while being compatible with pupil correction optical systems that have varying chief ray angles. This preserves measurement precision by effectively blocking disturbance light while still allowing target light to pass through across the entire field of view.
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 enables high-quality ranging imaging even under external light conditions by maintaining measurement accuracy and reducing noise from disturbance light.
Implementation Method 1
an optical member including a bandpass filter that is selectively transparent to infrared light in a predetermined wavelength range
Implementation Method 2
the bandpass filter has a concave-shaped light incident surface... an incident angle of oblique light can be reduced
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A distance measuring system includes a light source unit that emits infrared light toward a target object, a light receiving unit that receives the infrared light from the target object, and an arithmetic processing unit that obtains information regarding a distance to the target object on the basis of data from the light receiving unit, in which an optical member including a bandpass filter that is selectively transparent to infrared light in a predetermined wavelength range is arranged on a light receiving surface side of the light receiving unit, and the bandpass filter has a concave-shaped light incident surface.