Autocollimator Mirror on Star Tracker for Line of Sight Control
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Solution Overview
Problem
Existing startracker systems on satellites face biases between the line of sight of the space telescope and the Attitude Control System, which are difficult to resolve with existing solutions that rely on complex optical systems or unstable components.
Innovation Solution
A control system for the line of sight using a light source and a small autocollimation mirror integrated with the starfinder, where the light source and detector are in the focal plane, and a plane mirror reflects the collimated beam to the detector, with the position and shape of the light spot indicating the line of sight direction, and optionally using adaptive mirrors and masks for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a control system with a deflection mirror is used to control the line of sight, then the line of sight can be controlled, but the system relies entirely on the stability of the deflection mirror which introduces uncertainty
Solution Approach 1:
The patent replaces the mechanical deflection mirror system with an optical autocollimation system. Instead of using a deflection mirror that requires mechanical stability, the invention uses a fixed mirror integrated with the star tracker and an autocollimation optical path that eliminates mechanical instability issues. The line of sight control is achieved through optical feedback rather than mechanical deflection.
Solution Approach 2:
The patent introduces an intermediary autocollimation optical system between the light source and the detector. This intermediary system uses the fixed mirror and autocollimation principle to transfer the line of sight information without requiring the mirror itself to be stable, thus mediating between the light source and detection while eliminating the stability problem.
2Measurement precision
If complex optical systems are used to control the line of sight, then alignment accuracy can be improved, but the device complexity increases
Solution Approach 1:
The patent merges the line of sight control function with the existing star tracker structure by integrating a fixed mirror into the star tracker assembly. This consolidation eliminates the need for separate complex control optical systems while maintaining alignment accuracy. The autocollimation system uses the existing optical path of the telescope, further simplifying the overall device.
Solution Approach 2:
The fixed mirror integrated with the star tracker serves multiple functions: it acts as both the star tracker's optical component and the autocollimation system's reflection surface. The same optical path is used for both star tracking and line of sight control, making the system multi-functional without adding complexity.
3Stability of the object's composition
If thermoelastically stable structures are used to reduce bias between telescope and star tracker, then alignment stability is improved, but the structure has inherent limitations
Solution Approach 1:
The patent replaces the thermoelastically stable mechanical structure with an optical stabilization system. Instead of relying on special materials and structures to maintain alignment, the invention uses the autocollimation optical system to continuously monitor and determine the line of sight, eliminating the need for complex thermoelastic structural design.
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 solution provides precise control of the line of sight without relying on complex optical systems or stable deflection mirrors, allowing for accurate alignment and reduced mechanical and thermal constraints, while enabling the use of existing detectors and light sources.
Implementation Method 1
a plane mirror operating in self-collimation... the plane mirror reflects the collimated beam towards the detector
Implementation Method 2
reflecting the collimated beam coming from the light source towards the detector
Implementation Method 3
a light source located in the focal plane of the telescope... the light source emits light
Implementation Method 4
the position and the shape of the light spot focused on the detector coming from the reflection of the collimated beam
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5E
AI summary
The field of the invention relates to observation instruments comprising at least one telescope, a star finder (20) fixedly mounted on the telescope's frame (21, 22, 23), and a telescope line-of-sight control device. This device comprises a light source (30), a self-collimating plane mirror (31), and a detector (32), the light source and detector being located in the telescope's focal plane. In the observation instrument according to the invention, the plane mirror is fixed to the star finder and oriented to reflect the collimated beam from the light source towards the detector. The position and shape of the light spot focused on the detector resulting from the reflection of the collimated beam are representative of the line-of-sight direction.