In-Situ Phase Mask Calibration for Wavelength Changes
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Solution Overview
Problem
Existing phase masks, particularly spatial light modulators (SLMs), require calibration for optimal performance across different wavelengths, which is typically done before installation and cannot be easily recalibrated in situ without disassembly, affecting structured illumination in microscopes.
Innovation Solution
A method involving successive control of phase masks with varying gray value patterns while measuring light intensity downstream, allowing determination of the relationship between gray values and phase shifts, enabling in-situ calibration without disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If phase mask calibration is performed before installation using conventional methods, then calibration accuracy is achieved, but the phase mask cannot be recalibrated in situ without disassembly when wavelength changes occur
Solution Approach 1:
The system enables self-calibration by using the phase mask itself to generate calibration patterns and measure its own performance. The phase mask displays test patterns, the camera captures the resulting light distribution, and the system automatically calculates calibration data without requiring external calibration equipment or disassembly of the phase mask.
Solution Approach 2:
The calibration method uses the existing operational components (phase mask, light source, camera) for dual purposes: both for normal imaging operations and for calibration. The phase mask serves as both the device under calibration and the calibration pattern generator, eliminating the need for separate calibration equipment.
2Reliability
If the phase mask is recalibrated by disassembly and external calibration, then calibration accuracy is restored, but time loss and operational interruption occur
Solution Approach 1:
The system performs calibration measurements using successive gray value patterns that progressively refine the calibration data. By capturing multiple images with varying gray levels and calculating calibration values iteratively, the system achieves accurate calibration in a single in-situ operation without requiring preliminary disassembly or external calibration setup.
3Device complexity
If fixed calibration data is used for different wavelengths, then device simplicity is maintained, but structured illumination quality degrades
Solution Approach 1:
The calibration data is made dynamic and wavelength-dependent rather than fixed. The system calculates separate calibration values for different wavelength ranges based on measured light distribution patterns. This allows the calibration to adapt to wavelength changes while maintaining a simple operational interface where the appropriate calibration data is automatically selected based on the current wavelength.
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
Enables efficient recalibration of phase masks installed in optical devices, such as microscopes, maintaining optimal performance across wavelength changes due to temperature variations or control unit replacements, without requiring complex optical adjustments.
Implementation Method 1
a phase mask arranged in the beam path... The phase mask is successively controlled with different patterns of gray values... a relationship is determined between a second gray value and a phase offset imposed by the phase mask
Implementation Method 2
Bessel beams can be coherently superimposed... interference effects between individual Bessel beams to create an extended and structured light sheet
Implementation Method 3
the camera for measuring light in a detection beam path... at least a portion of a total intensity of the light in the beam path is measured downstream of the phase mask
Data Source
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AI summary
The invention relates, in a first aspect, to methods for calibrating a phase mask, in particular an SLM, in a beam path of an optical device, in particular a microscope, in which the following method steps are carried out: the phase mask is successively driven with different patterns of gray values, wherein a first gray value of a first subset of segments remains constant and wherein a second gray value of a second subset of segments is varied from one pattern to the next; the phase mask is illuminated with light from the optical device; at least a part of the total intensity of the light in the beam path is measured downstream of the phase mask for the different patterns, and a characteristic curve of the measured intensity as a function of the second gray value is obtained; from the characteristic curve, a relationship between the second gray value and a phase shift is derived.The phase mask is generated, and the phase mask is calibrated based on the obtained relationship between gray value and phase shift. The invention also relates to a microscope suitable for carrying out the method according to the invention.