Infrared Camera Modifier Module for Continuous Zoom and Focus
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Solution Overview
Problem
Infrared cameras face challenges in maintaining sharp image focus when transitioning between different optical fields and operating over a wide thermal range, with complex displacement laws for mobile optical groups complicating their operation.
Innovation Solution
The camera employs an afocal modifier module with a divergent and convergent mobile group, allowing adjustable focusing between infinity and a few tens of meters, and continuous variation of focal length, governed by simple polynomial laws for real-time digital processing, decoupling the functions of each optical group and enabling temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical cam is used to displace mobile optical groups for focusing, then focusing capability is achieved, but the displacement laws become complex and mechanical complexity increases
Solution Approach 1:
The patent replaces the mechanical cam system with a digital control system. Motorized groups are displaced according to simple polynomial laws that can be computed by digital processing, eliminating the need for complex mechanical cam mechanisms while maintaining focusing capability across the entire focusing area.
Solution Approach 2:
The patent uses polynomial laws with temperature-dependent coefficients to describe the displacement of mobile optical groups. By changing the parameters (coefficients) based on temperature, the system achieves accurate focusing across different thermal conditions without complex mechanical adjustments.
2Adaptability or versatility
If multiple mobile optical groups are used for zoom and focusing, then optical functionality is improved, but the displacement laws become complex and driving becomes difficult
Solution Approach 1:
The patent divides the optical system into distinct functional groups: a first mobile group for zooming and a second mobile group for focusing. Each group has a dedicated motorization and follows its own simple polynomial law, making the driving of multiple groups manageable despite the enhanced optical functionality.
Solution Approach 2:
The patent employs dynamic polynomial laws that can be computed in real-time by digital processing. The displacement of each mobile group is governed by simple polynomial relationships with temperature-dependent coefficients, enabling flexible and accurate control of multiple optical groups without complex mechanical linkages.
3Adaptability or versatility
If field switching is performed by switching in the optical path, then different optical fields are achieved, but temporary image loss occurs
Solution Approach 1:
The patent uses a continuous optical zoom system with mobile optical groups that can be displaced continuously without discrete switching. This allows smooth transition between different optical fields (e.g., 1° to 40°) while maintaining continuous image formation, eliminating the temporary image loss associated with mechanical field switching.
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 ensures continuous image focus without dead zones across varying focal distances and temperatures, improving mechanical simplicity and operational reliability, with accurate digital recopying of focal positions and focusing distances, and maintaining image sharpness over a wide range of fields and temperatures.
Implementation Method 1
The objective of the camera is formed by a modifier module which forms an intermediate image at infinity from an object plane located in the focusing area
Implementation Method 2
The image of a scene at the output of the modifier module is then conjugated on an array of an infrared detector by an imager module with fixed focal length
Implementation Method 3
an array of an infrared detector
Data Source
AI summary
The invention relates to an infrared camera comprising an optical zoom, characterized in that it comprises: —a matrix detector (5) comprising a cooled screen, a matrix able to detect infrared radiation; —a module (123) for modifying the focal length of the camera, the modifying module being able to vary the focal length of the camera so as to ensure the optical zoom function of the camera; and —an imager module (L4) able to ensure, for all the values of focal length of the camera: on the one hand the focusing of the infrared radiation on the matrix of the detector, and on the other hand the conjugation of the pupil of the camera on the cooled screen of the detector. The invention also relates to a method of observing a scene with the camera according to the invention.