Interference Filter Beam Turning Mirror for Compact Optical Scanners
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Solution Overview
Problem
Existing compact optical scanners face challenges in achieving a compact design and reduced component count due to the need for separate turning mirrors and beam-turning functions, which restricts their size and efficiency.
Innovation Solution
Integration of a thin-film interference filter that acts as both a turning mirror and a bandpass filter, utilizing angular selectivity to pass light at low angles and reflect it at higher angles, eliminating the need for a separate turning mirror and reducing stray light reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a separate turning mirror is used to direct light, then the beam can be turned, but the device size and component count increase
Solution Approach 1:
The patent combines the turning mirror function with the interference filter into a single integrated component. The interference filter is designed to reflect light at specific angles while transmitting light at other angles, thereby performing both beam turning and wavelength filtering functions simultaneously. This eliminates the need for a separate turning mirror and reduces the overall component count in the optical scanning system.
Solution Approach 2:
The interference filter is designed to serve multiple functions: it acts as a beam turning element by reflecting light at specific angles, a wavelength filter by blocking unwanted wavelengths, and a structural component of the optical path. This multi-functionality resolves the contradiction by making a single component perform what previously required multiple separate components.
2Ease of operation
If a separate turning mirror is used, then beam direction can be controlled, but the scanner size increases
Solution Approach 1:
By merging the turning mirror and interference filter into a single integrated component, the patent reduces the physical space required for beam direction control. The interference filter is positioned in the optical path and performs the beam turning function through its angular selectivity, eliminating the need for a separate turning mirror that would occupy additional space in the scanner assembly.
3Use of energy by moving object
If light is allowed to pass through without angular selectivity, then transmission is high, but stray light reaches the receiver
Solution Approach 1:
The interference filter is designed with angular selectivity that provides different optical properties at different angles. Light incident at specific angles (within the predefined angular range) is transmitted, while light at other angles (outside the predefined angular range) is reflected. This local differentiation of optical properties allows the system to distinguish between desired signal light and stray light based on their angles of incidence.
Solution Approach 2:
The interference filter utilizes changes in the optical parameters (wavelength and angle of incidence) to achieve selective transmission and reflection. By designing the filter with specific optical characteristics that vary with angle, the system can transmit light within a predefined wavelength range at specific angles while blocking stray light at different angles, thus resolving the contradiction between transmission and stray light rejection.
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 approach results in a more compact scanner design with reduced component count, improved light management, and enhanced efficiency by allowing the same substrate to function as both a turning mirror and a transparent plate, while effectively blocking undesired stray light.
Implementation Method 1
An interference filter is positioned between the scanner and the field of view and is configured to pass light within a predefined wavelength range that is incident on the interference filter at angles within the predefined angular range, while reflecting the light within the predefined wavelength range that is incident on the interference filter at an angle that is outside the predefined angular range
Implementation Method 2
the interference filter includes a bandpass filter, having a passband that contains the predefined wavelength range for rays that are incident on the interference filter at angles within the predefined angular range
Implementation Method 3
the interference filter includes a high-pass filter, having a band edge at a first wavelength longer than a maximum wavelength value of the predefined wavelength range for rays that are incident on the interference filter at angles within the predefined angular range, wherein for incidence at the angle that is outside the predefined angular range, the band edge shifts to a second wavelength that is shorter than a minimum wavelength value of the predefined wavelength range
Data Source
AI summary
Scanning apparatus includes a scanner, which is configured to scan over a field of view falling within a predefined angular range. An interference filter is positioned between the scanner and the field of view and is configured to pass light within a predefined wavelength range that is incident on the interference filter at angles within the predefined angular range, while reflecting the light within the predefined wavelength range that is incident on the interference filter at an angle that is outside the predefined angular range. An ancillary optical element communicates optically with the scanner at a wavelength within the predefined wavelength range via a beam path that reflects from the interference filter at the angle that is outside the predefined angular range.