Low F-Number Refractive Telescope With Dynamic Altitude Compensation
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Solution Overview
Problem
Refractive telescopes with low f-numbers are sensitive to temperature and altitude changes, leading to image quality degradation due to thermal expansion and air pressure variations, which complicates athermalization and requires complex and costly material matching and mechanical adjustments.
Innovation Solution
A low f-number refractive variable focus telescope system that dynamically controls temperature using a software-controlled heater and a housing material with a high coefficient of thermal expansion, such as aluminum, to maintain diffraction-limited performance across a wide temperature and altitude range, incorporating sensors for closed-loop feedback and ambient pressure compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional athermalization techniques are used with low f-number refractive telescopes, then material matching complexity and manufacturing cost increase, but temperature sensitivity remains high
Solution Approach 1:
The patent changes the operating temperature parameter by actively heating the telescope to 50°C, transforming the athermalization approach from passive material matching to active temperature control. This allows the use of simpler, lighter materials like aluminum while maintaining image quality across varying ambient temperatures.
Solution Approach 2:
The patent replaces complex mechanical athermalization mechanisms (such as precision-spaced lens assemblies requiring tight tolerances) with a thermal control system using heaters and temperature sensors. This substitution simplifies mechanical design and reduces manufacturing complexity.
2Reliability
If CTE matched housing materials are used to compensate for thermal expansion, then weight and cost increase, but thermal sensitivity is reduced
Solution Approach 1:
The patent changes the temperature parameter by maintaining the housing at 50°C, which allows the use of lightweight materials like aluminum instead of heavy CTE-matched materials such as Invar or titanium. The active heating compensates for the higher CTE of aluminum, enabling weight reduction while maintaining thermal stability.
Solution Approach 2:
The patent uses inexpensive, readily available materials like aluminum for the housing instead of expensive, specialized CTE-matched materials. The cost benefit is achieved through active temperature control rather than expensive material selection.
3Measurement precision
If mechanical motion focus adjustment techniques are used, then device complexity and weight increase, but focus precision is improved
Solution Approach 1:
The patent replaces mechanical focus adjustment mechanisms (such as motor-driven lens positioning or piezoelectric flexures) with thermal expansion/contraction of the housing. By controlling the housing temperature, the focal length is adjusted passively through thermal effects, eliminating complex mechanical systems.
Solution Approach 2:
The patent exploits thermal expansion of the aluminum housing to achieve focus adjustment. As the housing temperature changes, the dimensional changes naturally adjust the optical path and focal length, providing a simple and effective focus control mechanism without mechanical moving parts.
4Reliability
If heaters are used to maintain constant temperature, then power consumption increases, but image quality stability is improved
Solution Approach 1:
The patent implements a feedback control system using temperature sensors to monitor the housing temperature and adjust heater power accordingly. This closed-loop control maintains the housing at 50°C while minimizing energy consumption by reducing heater power when ambient temperature is close to the target temperature.
Solution Approach 2:
The heating system operates periodically rather than continuously, activating the heater only when the temperature deviates from the 50°C setpoint. This periodic heating reduces overall power consumption while maintaining image quality stability through temperature regulation.
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 system achieves improved focus control and reduced thermal gradients, enabling compact, efficient, and cost-effective operation with rapid dynamic focusing adjustments, expanding the operational envelope and reducing testing and calibration times.
Implementation Method 1
regulating, with a controller that is in operative communication with the first temperature-sensing device and the pressure-sensing device, a heater that is coupled directly or indirectly to the telescope housing to achieve diffraction limited performance
Implementation Method 2
a housing material with an increased coefficient of thermal expansion
Data Source
AI summary
A system and method are disclosed for a low F-number precision variable-focus telescope that includes a telescope housing containing an optical system. There is a first temperature sensing device to detect a temperature of the telescope housing, a second temperature sensing device to detect an ambient temperature around the telescope housing, and a pressure sensing device to detect ambient pressure around the telescope housing. A controller is in operative communication with the first temperature-sensing device, the second temperature sensing device, and the pressure sensing device. The control regulates the heater to maintain the telescope at a desired temperature to achieve diffraction limited performance in response to signals from the first temperature-sensing device, the second temperature sensing device, and the pressure sensing device.