Measuring \(\Psi\) using an experimental setup. Computation of \(\Psi\) using interferometric methodsĪs discussed above, the first step necessary for the calibration involves One can estimate matrix \(\Psi\) by recording experimentalĭata in an optical breadboard setup. TheĬolumns of \(\Psi\) therefore represent sampled versions of the influenceįunctions \(\psi\). Vector and, as a result, one has that \(\Psi\) is an \(N_c \times N_a\) matrix. Signals \(\mathbf\) can also be recognised as a Model \(\Psi\), which explains the relationship between the input control In practical terms, calibration of the DM involves generating a mathematical As this task must be performed a single time only, itĬan be successfully completed even in an inefficient manner. In this case, one could optimise the configuration of theĪctuators directly, for example by running a general model-free optimisation One such example is using the DM to remove time-invariantĪberration present in a microscope, such as aberrations due to optical On the contrary, there can be scenarios where calibration of the DM is a Such as spherical aberration, which develops when focusing through refractive Finally,Ĭalibration is necessary when seeking control of specific DOFs of interest, Individual DOF affects the optimal configuration of the other DOFs. To a more troublesome optmisation problem. Orthogonalise the DOFs that are spanned by the DM actuators, which also leads A similar side effect is also encountered if one does not With multiple optimal solutions – each exhibiting a different value for the Make the optimisation problem more challenging, since it endows this latter Maintaining piston as an active DOF when optimising the shape of the DM does Phase and has no side effects on the quality of the recorded images. This latter only affects the mean value of the Microscopes, this would entail at least removing some unnecessary degrees ofįreedom (DOF) such as piston. Optimise the shape of the DM in the most efficient manner possible. Similarly, calibration is a requirement if one is seeking to For example, one may be interested in determining a quantitativeĮstimate of the shape of the DM given a particular arrangement of theĪctuators. Neglected if accurate wavefront modulation is sought for a particularĪpplication. In most scenarios, calibration of the DM is a prerequisite that cannot be Obtaining this information is the goal of the DM calibration. Understand how the active area of the DM responds when actuators are operated. Control of a DM thereforeĬonsists in choosing which configuration to apply to the actuators in order to
Abscissa mirror free#
Only consider DMs that are free of such non-linear effects.ĭespite heterogeneity in the underlying technology, virtually all DMs compriseĪ number of reflective segments or a continuous membrane that can beĪdaptively manipulated using an array of actuators. Required for wavefront sensorless adaptive optics. Hysteresis and creep, which render them unsuitable for open-loop control, as Nevertheless, the former ones suffer from non-linear effects such as Inter-actuator coupling with respect to electrostatically actuated DMs. On piezoelectric actuation typically feature larger stroke and less
Abscissa mirror how to#
How to carry out the calibration procedure using an interferometer.ĭeformable mirrors have been manufactured using different technologies, eachĮxhibiting its own advantages and inconveniences with respect to individualĪpplications. Once aĭM is deployed in an optical path, it must be calibrated so that the desired Point-spread function and correction of aberrations in an instrument. Useful in microscopy applications, where they allow both engineering of the Profile on a beam of light upon reflection. Introductionĭeformable mirrors (DM) are devices that impress a controllable wavefront This protocol,Īccompanying software, and hardware design facilitate calibration ofĭeformable mirrors for a range of applications. Instructions to build a compact, slot-in interferometer. We provide a reference implementation for this method in Twyman-Green interferometer setup, combined with single-frame fringe analysisįor phase extraction. This tutorial discusses the static calibration of a deformable mirror using a We consciously acknowledge all of these contributions, even though it is impractical to list them all here As the content is the culmination of long term work in the Dynamic Optics and Photonics Group, many others have contributed directly or indirectly to this material.
The listed authors have participated in the writing of this document.
Abscissa mirror pdf#
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