Plastic Collimating Lens for Stable 3D Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional smartphone collimating lenses experience significant changes in focal length and light projection angles due to temperature fluctuations, affecting 3D imaging accuracy and clarity, and are difficult and costly to mass-produce due to the use of molded glass lenses.
Innovation Solution
A collimating lens design comprising three plastic lenses with specific refractive power and surface shapes, including a first lens with positive refractive power, a second lens with negative refractive power, and a third lens with positive refractive power, along with a stop, which limits temperature coefficient changes to ensure stable focal length and reduced production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a molded glass lens is used in the collimating lens, then the lens can be produced, but it is difficult to mass produce, low in yield, and increases production costs
Solution Approach 1:
The patent changes the material parameter from glass to plastic for the molded lens. This allows the lens to be manufactured using injection molding processes, which are highly suitable for mass production. The plastic material can be molded directly into the final lens shape, significantly improving production yield and reducing costs while maintaining the required optical performance through proper selection of plastic materials with appropriate refractive indices.
2Temperature
If the focal length of the lens changes with temperature, then the lens can adapt to temperature variations, but the angle of light projected changes significantly, causing deviation in 3D object reconstruction accuracy
Solution Approach 1:
The patent selects plastic materials with specific temperature coefficients of refractive index that compensate for thermal expansion effects. By carefully choosing materials where the refractive index changes in a controlled manner with temperature, the patent offsets the focal length changes caused by thermal expansion, thereby maintaining stable light projection angles and preserving 3D reconstruction accuracy across varying temperatures.
Solution Approach 2:
The collimating lens is designed as a composite structure combining multiple plastic lens elements with different thermal-optical properties. By combining materials with complementary temperature coefficients of refractive index, the patent creates a composite lens system where the thermal effects of one element compensate for the thermal effects of another, achieving temperature stability in the overall optical system.
3Measurement precision
If the focal length remains stable with temperature changes, then the light projection angle remains consistent, but this requires precise control of refractive index temperature coefficients
Solution Approach 1:
The patent establishes specific ranges for the temperature coefficients of refractive index that the selected plastic materials must satisfy. By defining these parameter ranges, the patent simplifies the material selection process while ensuring that the chosen materials will produce the desired temperature-stable optical performance. This parameter-based approach provides clear design criteria that guide material selection without requiring complex calculations or iterations.
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 provides a stable focal length and improved 3D imaging accuracy across varying temperatures, while reducing production costs by using plastic lenses, thus enhancing the implementation of 3D structured-light algorithms in smartphones.
Implementation Method 1
The first lens has a positive refractive power, the second lens has a negative refractive power, the third lens has a positive refractive power
Implementation Method 2
The material of each of the first lens, the second lens, and the third lens is plastic. The collimating lens satisfies: (dn/dt)1−6/° C.; (dn/dt)2−6/° C.; (dn/dt)3−6/° C.
Data Source
AI summary
The disclosure provides a collimating lens, a projecting module, and a mobile phone. An object side of the collimating lens is defined as adjacent to a laser transmitter, an image side of the collimating lens is defined as adjacent to an object to be measured. Along an optical axis from the object side to the image side, the collimating lens sequentially includes a first lens, a second lens, a third lens and a stop. An object side surface of the first lens is convex, an object side surface of the second lens is concave surface, an object side surface of the third lens is convex, and an image side surface of the third lens is convex. The stop is positioned between the third lens and the object to be measured. The material of each of the first lens, the second lens, and the third lens is plastic.