Compact MEMS Beam Scanner Packaging With Integrated VCSEL Optics
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Solution Overview
Problem
Existing beam scanners are large and bulky due to the need for clearance around scanning mirrors and external light sources and optics, limiting their utility in compact applications.
Innovation Solution
A compact beam scanner design incorporating a vertical-cavity surface-emitting laser (VCSEL) light source, collimating optics, and a MEMS scanner within a low-profile package, with integrated monitor photodetectors and actuators for precise beam steering and position feedback, housed in a sealed chamber that mitigates stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If prior-art scanning mirrors and actuators are used with sufficient clearance for large rotation, then the scanning function is achieved, but the package dimensions become necessarily quite large
Solution Approach 1:
The patent integrates the light source, collimating optics, and scanning mirror into a nested configuration where the light source is positioned beneath the scanning mirror and the collimating optics are integrated within the same package. This nesting allows the components to share space efficiently, enabling large scanning rotation without proportionally increasing package dimensions.
Solution Approach 2:
The patent positions the light source in the vertical dimension beneath the scanning mirror rather than requiring lateral clearance. This dimensional reorganization allows the scanning mirror to rotate through large angles without requiring proportionally large horizontal package dimensions, as the light path utilizes the vertical space efficiently.
2Ease of operation
If light sources and refractive collimating optics are placed outside the scanning-mirror package, then beam scanning function is achieved, but the space required for such beam scanners increases
Solution Approach 1:
The patent merges the light source, collimating optics, and scanning mirror into a single integrated package. The light source is positioned beneath the scanning mirror, and the collimating optics are integrated within the same housing, eliminating the need for separate external components and reducing the total volume required for beam scanning functionality.
Solution Approach 2:
The scanning mirror package is designed to perform multiple functions simultaneously: generating light (via integrated VCSEL), collimating the light (via integrated optics), and scanning the beam (via mirror rotation). This multi-functionality eliminates the need for separate external components, reducing overall system volume while maintaining full beam scanning capability.
3Ease of operation
If traditional light sources and optical elements are used, then beam scanning is achieved, but they are typically large, bulky, and expensive
Solution Approach 1:
The patent employs VCSELs (vertical-cavity surface-emitting lasers) which emit light in a vertical direction, changing the traditional lateral light emission parameter. This parameter change allows the light source to be positioned beneath the scanning mirror and efficiently coupled to the collimating optics, enabling a compact integrated design that reduces component size and cost compared to traditional lateral-emitting light sources.
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
Enables high-resolution object tracking with a reduced footprint and lower cost, suitable for mobile devices and various applications including eye tracking and VR/AR systems.
Implementation Method 1
The light source is a vertical-cavity surface-emitting laser (VCSEL), which provides a light signal to a scanning element of the MEMS scanner
Implementation Method 2
collimating optics, which are enclosed within a sealed chamber of a low-profile package housing. The light source is a vertical-cavity surface-emitting laser (VCSEL), which provides a light signal to a scanning element of the MEMS scanner via the collimating optics
Implementation Method 3
The scanning element is a mirror whose orientation about two axes is controlled via a pair of actuators. The mirror reflects the collimated beam as an output beam that exits the module
Implementation Method 4
the mirror position is monitored by the monitor photodetectors, which are monolithically integrated with the MEMS scanner on the same substrate
Implementation Method 5
the housing is configured to mitigate propagation of scattered light within the package
Implementation Method 6
the housing is configured to function as an electrostatic shield for the MEMS scanner, light source, and monitor photodiodes
Data Source
AI summary
The present disclosure is directed to compact packaging for optical MEMS devices, such as one- and two-dimensional beam scanners. An embodiment in accordance with the present disclosure includes a housing that defines a sealed chamber that encloses a light source, a MEMS scanner having a scanning element for steering at least a portion of a light signal provided by the light source in two dimensions as an output signal, an optical element for collimating and/or redirecting the light signal, and a monitor photodiode for providing a local feedback signal based on the orientation of the scanning element. Preferably, the MEMS scanner and the monitor photodiode are monolithically integrated on the same substrate and the housing is configured as an electrostatic shield for the components located in the sealed chamber.