Helicoidal Prism Scanning Interferometer Speed
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Solution Overview
Problem
Conventional scanning interferometers using linear motion of wedge prisms for scanning interferograms face limitations in achieving high scanning speeds due to the need for constant acceleration, deceleration, and direction reversal, which restricts spectral resolution and efficiency.
Innovation Solution
The implementation of a rotating wedge-shaped helicoidal prism in one arm of the interferometer, allowing both arms to pass through similar helicoidal prisms, enables high-speed scanning by varying the optical path in one arm while keeping the other arm's path constant, utilizing a rotating motion around its axis parallel to the optical axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If linear motion of wedge prism is used for scanning, then scanning is achieved, but scanning speed is limited due to constant acceleration and deceleration
Solution Approach 1:
The patent applies a helicoidal (curved) surface to the prism instead of a linear wedge shape. The helicoidal surface allows the optical path length to vary continuously and smoothly with rotation angle, enabling high-speed scanning without the acceleration-deceleration cycles required by linear motion. The curved geometry transforms the scanning mechanism from linear往复运动 to rotational continuous motion.
Solution Approach 2:
The patent transitions from static linear wedge prism motion to dynamic rotational helicoidal prism motion. The rotating helicoidal prism creates a time-varying optical path difference through continuous rotation, allowing the system to achieve high scanning speeds by maintaining constant rotational velocity rather than undergoing repeated acceleration and deceleration cycles.
2Measurement precision
If wedge prism moves back and forth, then interferogram scanning is achieved, but spectral resolution is reduced due to motion constraints
Solution Approach 1:
The helicoidal surface geometry provides a continuous, smooth variation of optical path length with rotation angle, eliminating the discrete steps and motion reversals that limit spectral resolution in linear wedge prism systems. This curved geometry enables both high scanning speed and high spectral resolution simultaneously.
Solution Approach 2:
The patent replaces the mechanical linear往复运动 system with a rotational system. The rotation of the helicoidal prism substitutes for the back-and-forth linear motion of the wedge prism, transforming the mechanical constraints into a more efficient rotational motion that achieves both high speed and high precision.
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 enhances scanning speed and efficiency by allowing the scanning helicoidal prism to rotate at high speeds in one direction, maintaining constant optical path in one arm and increasing it in the other, thereby improving spectral resolution and scanning performance.
Implementation Method 1
The helicoidal prism formed by flat surface and helicoidal surface placed in such a way into one arm of the interferometer capable to make rotating motion in one directions around its axis of movement... when the optical path refractively increases in one arm of the interferometer
Data Source
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AI summary
To increase speed of scanning of the scanning blocks of interferometric spectrometers used in Fourier spectroscopy, use is made of a scanning block which is made of helicoidal prism, while the scanning block is installed in the interferometer so, that one arms of the interferometer pass through it and the block has the possibility of rotational movement around its pivot which is parallel to the interferometer arm optical axis, whereas rotational movement of the scanning block round the pivot brings along increase or decrease of optical path in one arm of the interferometer. The other, similar stationary helicoidal prism (compensating prism) is installed in the other arm of the interferometer to compensate refraction caused by the scanning helicoidal prism. Retroreflectors, used in the interferometer, can be either cube corner, or cats eye type mirrors.