Collinear Holographic Reading Device Thermal Deformation Compensation
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Solution Overview
Problem
Collinear holographic data storage systems face challenges due to thermal deformation of the storage medium, which weakens the diffracted beam and results in a poor point spread function (PSF), limiting the operational temperature range and affecting data storage quality.
Innovation Solution
A reading device is developed that includes a spatial light modulator, a zoom lens set, an object lens, and an adjusting module, which adjusts the optical magnification based on the quality of the diffraction signal and temperature measurements to compensate for thermal deformation, ensuring optimal data retrieval by maintaining the optical field consistency of the diffracted beam with the signal beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reading beam is focused onto the collinear holographic storage medium without compensation, then the system structure remains simple, but thermal deformation weakens the diffracted beam and degrades the point spread function
Solution Approach 1:
The patent applies dynamics by making the optical magnification of the reading beam dynamically adjustable through a zoom lens system. The magnification is changed in response to temperature variations to compensate for thermal deformation of the storage medium, thereby maintaining beam quality and point spread function under varying thermal conditions
Solution Approach 2:
The patent changes the optical parameter (magnification) of the reading beam to compensate for thermal effects. By adjusting the magnification parameter according to temperature, the system counteracts thermal deformation and maintains optimal focusing conditions on the holographic storage medium
2Manufacturing precision
If the optical magnification is fixed, then the device operation is simple, but the point spread function deteriorates under thermal deformation
Solution Approach 1:
The patent implements feedback control by monitoring temperature and using this information to adjust the optical magnification of the reading beam. This closed-loop approach ensures that the point spread function is maintained at optimal levels by compensating for thermal deformation effects in real-time
Solution Approach 2:
The optical magnification is made dynamic rather than fixed, allowing the system to adapt to temperature changes. The zoom lens system enables continuous adjustment of magnification to maintain focusing precision on the storage medium despite thermal expansion or contraction
3Reliability
If the reading beam phase is not modulated, then the device structure is simpler, but thermal deformation causes beam weakening and poor focusing
Solution Approach 1:
The patent modulates the phase parameter of the reading beam to compensate for thermal deformation effects. By changing the phase distribution across the beam profile, the system maintains optimal focusing conditions and beam quality on the holographic storage medium despite temperature variations
Data Source
AI summary
A reading device includes a spatial light modulator, a zoom lens set, an object lens, an image sensor, and an adjusting module. The spatial light modulator provides a reading beam. The zoom lens set forms the reading beam into a real image. The object lens focuses the real image onto a collinear holographic storage medium and thus produces a diffraction signal. The image sensor converts the diffraction signal into an electric signal. The adjusting module adjusts the optical magnification of the zoom lens set according to the quality of the diffraction signal.