Light Source Device with Inclined Beam Splitter for Feedback Control
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Solution Overview
Problem
Conventional optical scanning devices using surface-emitting lasers face challenges with light stability due to feedback light and dust accumulation, leading to inconsistencies in image density and reduced service life, while also being limited by long optical paths and inaccurate auto power control.
Innovation Solution
A light source device with a package member, a splitting element, and a cap member that inclines the splitting element to prevent feedback light, combined with a monitoring light beam system to maintain light stability and dust protection, allowing for precise auto power control and downsizing of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a beam splitter is used to branch a light beam for monitoring in surface-emitting laser systems, then light amount control becomes possible, but the optical path length becomes long and device downsizing is disturbed
Solution Approach 1:
The beam splitter is integrated within the sealed package structure, nesting the monitoring optical path inside the existing package volume. This allows the optical path to be folded back on itself, reducing the external dimensions while maintaining the necessary optical path length for accurate monitoring
Solution Approach 2:
The optical path is arranged in a three-dimensional configuration within the package rather than a linear extension. By utilizing vertical and lateral spaces within the package, the optical path achieves sufficient length for accurate monitoring without increasing the overall device footprint
2Object-affected harmful factors
If a cover glass is provided for dust proofing, then dust protection is improved, but feedback light enters the laser and deteriorates light stability
Solution Approach 1:
The harmful feedback light path is extracted and redirected away from the laser diode. The beam splitter positioned at a specific angle intercepts light that would otherwise reflect off the cover glass and return to the laser, diverting it toward the monitoring photodetector instead
Solution Approach 2:
The beam splitter acts as an intermediary element between the cover glass and the laser diode. It intercepts the feedback light path and redirects it, preventing the direct feedback loop while maintaining the cover glass's protective function
3Reliability
If conventional APC methods are used with surface-emitting lasers, then light output fluctuation can be suppressed, but the device size increases due to long optical paths
Solution Approach 1:
The entire APC optical system is nested within the sealed package, with the beam splitter, monitoring photodetector, and associated optics arranged in a compact three-dimensional configuration that fits within the existing package volume
Solution Approach 2:
The monitoring function is integrated into the existing package structure by combining the beam splitter with the package housing or mounting structure, eliminating the need for separate external monitoring components and reducing overall device volume
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 ensures stable light emission, prevents dust accumulation, and maintains high scanning accuracy, enabling efficient and consistent image formation while reducing the device's size and weight.
Implementation Method 1
a beam splitting unit reflects a part of the laser beam to make a photoreceptor detect a light amount
Data Source
AI summary
A light source device includes: a light source; a package member that holds the light source; a splitting element that is arranged on an optical path of a light beam output from the light source and splits the light beam into a first light beam and a second light beam; and a cap member that holds the splitting element so that the surface of the splitting element is inclined with respect to a plane orthogonal to a traveling direction of the light beam output from the light source and that is attached to the package member to seal the light source.