ToF Optical Layout With Microlens Afocal Beam Splitting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing time-of-flight distance measurement systems face challenges in achieving a compact and high-resolution design due to the difficulty in matching the angle of view of light emitting and receiving elements, which is exacerbated by the use of diffractive optical elements that expand the angle of view, making it hard to create a compact apparatus with high resolution.
Innovation Solution
The optical apparatus includes a light emitter with a microlens array and a telecentric lens system that divides light into multiple beams, allowing for a one-to-one correspondence between light emitting and receiving elements, forming an afocal system that maintains a consistent projected image size regardless of distance, enabling high-resolution distance measurement while reducing noise and pixel size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a diffractive optical element is used to increase the resolution of projected light, then the number of light beams is multiplied, but the angle of view is expanded requiring a larger light receiving element array
Solution Approach 1:
The optical element is divided into multiple microlenses (first microlenses and second microlenses) that are arranged in a specific pattern. Each microlense focuses light to form a line light source, and the segmented structure enables high-resolution projection without expanding the overall angle of view, thus avoiding the need for a larger light receiving element array.
Solution Approach 2:
The patent transitions from point light sources to line light sources by arranging microlenses in a linear configuration. This dimensional change from 0D (point) to 1D (line) allows the system to achieve higher resolution in one dimension without proportionally increasing the angle of view in all dimensions, thereby maintaining a compact light receiving element array size.
2Area of stationary object
If the light emitting element array and light receiving element array have approximately the same sizes to share the imaging lens, then the apparatus size is reduced, but the angle of view matching becomes difficult
Solution Approach 1:
Different regions of the optical system are assigned different functions: the first microlenses and second microlenses are positioned at different locations and have different focal lengths, creating local quality variations. This allows each region to contribute differently to the overall angle of view, enabling both light emitting and receiving elements to have matching angles of view while maintaining compact sizes.
Solution Approach 2:
The patent changes key parameters including the focal lengths of different microlenses (first focal length f1 and second focal length f2), the arrangement positions of microlenses, and the pitch ratios between light emitting elements and microlenses. These parameter adjustments enable angle of view matching between light emitting and receiving elements while keeping the apparatus compact.
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
This configuration allows for accurate and high-resolution distance measurement with reduced noise and pixel size, achieving a compact and efficient optical apparatus suitable for on-board systems and movable applications.
Implementation Method 1
an optical element including a plurality of microlenses, an optical system including a first telecentric lens
Implementation Method 2
a processor configured to acquire distance information to an object based on a time required from when the light emitter emits light to when the light receiver receives the light reflected by the object
Data Source
AI summary
An optical apparatus includes a light emitter including at least one light emitting element, a light receiver including a plurality of light receiving elements, an optical element including a plurality of microlenses, an optical system including a first telecentric lens, and a processor configured to acquire distance information to an object based on a time required from when the light emitter emits light to when the light receiver receives the light reflected by the object. The number of microlenses is larger than the number of light emitting elements. The plurality of microlenses and the first telecentric lens form an afocal system.