Interferometer Apparatus Angular Dependence Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Babinet-Soleil based interferometers are sensitive to light direction due to angle-dependent birefringence, limiting their use with extended light sources and reducing interferometric contrast, especially in imaging applications where angular dependencies cause loss of modulation and reduced signal-to-background ratio.
Innovation Solution
An interferometer apparatus with an adjustable birefringent device and compensation optical device, featuring a wedge pair and birefringent plates, is designed to minimize angular dependence by introducing adjustable time delays that compensate for the angular dependence of the birefringent material, ensuring consistent optical path differences across different angles of incidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a Babinet-Soleil compensator with two birefringent optical crystals is used to create variable delay between orthogonal polarization replicas, then the interferometer can achieve adjustable time delay and negative delays, but the device becomes very sensitive to light travelling direction due to angle-dependent birefringence
Solution Approach 1:
The patent introduces a compensation optical device with specific optical properties that counteracts the angle-dependent birefringence in localized regions of the optical path. By placing compensating optical elements at specific positions and orientations, the system locally corrects the angular sensitivity without affecting the overall adjustable delay capability.
Solution Approach 2:
The system combines multiple optical materials with different birefringent properties to create a composite optical path. By using materials with complementary characteristics, the overall system achieves reduced angular dependence while maintaining the desired time delay adjustment range.
2Volume of moving object
If the interferometer uses birefringent material with angle-dependent path length to create optical path difference, then compact and robust design is achieved, but the device performs poorly with extended light sources due to angular dependency
Solution Approach 1:
The patent modifies the optical path parameters by introducing compensation elements that change the effective path length experienced by different angular components of the light. This allows the compact birefringent design to work with extended sources by equalizing the optical path difference across various incident angles.
3Device complexity
If a single pixel detector spatially integrates the intensity profiles of the output beam, then the detection process is simplified, but the interference contrast decreases due to integration of multiple fringes
Solution Approach 1:
The compensation optical device creates equipotential conditions for the optical path by ensuring that all angular components of the extended light source experience the same effective optical path difference. This results in uniform interference fringes across the beam profile, allowing spatial integration by a single pixel detector without loss of contrast.
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 design enhances interference quality, allowing the interferometer to effectively handle both single-point and extended radiation sources, improving contrast and sensitivity, and maintaining high performance across various angles, thus overcoming the limitations of traditional Babinet-Soleil interferometers.
Implementation Method 1
by using a birefringent material it is possible to divide the two replicas based on their polarization. The optical path difference is given by the different velocities of the replica polarizations travelling through a birefringent material
Implementation Method 2
The path travelled by one of the two replicas can be varied and the two are then recombined into one output beam making interference possible
Data Source
AI summary
An interferometer apparatus comprises an adjustable birefringent device configured to receive an input radiation and produce corresponding replicas having reciprocally orthogonal polarizations and delayed from each other by an adjustable time delay. The birefringent device also introduces an additional time delay between the replicas. The interferometer apparatus also comprises a compensation optical device optically coupled to the adjustable birefringent device and configured to have a respective structural thickness and respective ordinary and extraordinary refractive indexes to introduce a compensation time delay between the replicas having a sign opposite to a sign of the additional time delay.