Optical Module Inclined Light Receiving Faces Reduce Stray Light
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Solution Overview
Problem
Optical modules with semiconductor lasers often experience stray light due to backward light being reflected at perpendicular light receiving faces, which can exit the module and reach unintended locations, compromising device functionality.
Innovation Solution
The optical module incorporates a light forming unit with red, green, and blue semiconductor lasers, each with a corresponding lens to adjust spot size, and inclined light receiving faces relative to the optical axis of backward light to prevent reflection into the same light path as forward light, reducing stray light occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light receiving face is disposed perpendicular to the optical axis of backward light, then the light receiving device can efficiently receive backward light, but reflected light exits the module and reaches unintended locations causing stray light
Solution Approach 1:
The light receiving face is disposed at an inclined angle (e.g., 45 degrees) relative to the optical axis of backward light, breaking the symmetric perpendicular arrangement. This asymmetric configuration causes reflected light to exit at a different angle rather than returning along the same path, thereby preventing stray light while maintaining efficient light reception
2Object-generated harmful factors
If the light receiving face is inclined relative to the optical axis of backward light, then stray light is reduced, but the light receiving efficiency may be compromised
Solution Approach 1:
The inclined light receiving face converts the potentially harmful reflection (stray light) into a beneficial outcome by directing reflected light away from the optical path. The inclination angle is specifically designed so that while backward light is still effectively received, the reflected light is redirected to a safe exit path that does not interfere with the forward light path
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 effectively minimizes stray light by ensuring backward light is not reflected into the same path as forward light, enhancing the module's performance and reducing unwanted light exit.
Implementation Method 1
a first light receiving device disposed on the base member and having a first light receiving face that receives backward red light emitted from the red semiconductor laser
Implementation Method 2
The first light receiving face, the second light receiving face, and the third light receiving face are inclined relative to a plane perpendicular to an optical axis of the backward red light, a plane perpendicular to an optical axis of the backward green light, and a plane perpendicular to an optical axis of the backward blue light, respectively
Implementation Method 3
a first lens disposed on the base member to change a spot size of light emitted from the red semiconductor laser, a second lens disposed on the base member to change a spot size of light emitted from the green semiconductor laser, and a third lens disposed on the base member to change a spot size of light emitted from the blue semiconductor laser
Data Source
AI summary
An optical module includes a base member, a red semiconductor laser, a green semiconductor laser, a blue semiconductor laser, a first light receiving device having a first light receiving face that receives backward red light emitted from the red semiconductor laser, a second light receiving device having a second light receiving face that receives backward green light emitted from the green semiconductor laser, a third light receiving device having a third light receiving face that receives backward blue light emitted from the blue semiconductor laser, wherein the first light receiving face, the second light receiving face, and the third light receiving face are inclined relative to planes perpendicular to optical axes of the backward red light, the backward green light, and the backward blue light, respectively, to reduce the likelihood of occurrence of stray light.