We will present a new approach of the linearized focal plane technique (LIFT), formerly developed by ONERA, which results in an improvement of a factor of 16 (4x4) of the spatial resolution. This technology is based on the combination of standard SH technology with phase retrieval algorithms applied on all spots of the microlens array that provides information on high spatial frequencies. We will show some measurements performed on extremely complex wavefronts. This technology presents very promising perspectives for optical and freeform metrology and can advantageously replace, at lower cost and better usability, Fizeau interferometry.
We will present a new approach of linearized focal plane technique (LIFT), formerly developed by ONERA, which results in an improvement of a factor of 16 (4x4) of the spatial resolution. This technology is based on the combination of standard SH technology with phase retrieval algorithms applied on all spots of the microlens array that provides information on high spatial frequencies. We will show some measurements performed on extremely complex wavefronts. This technology presents very promising perspectives for optical and freeform metrology and can advantageously replace, at lower cost and better usability, Fizeau interferometry.
Euclid is the second M-class mission of ESA’s Cosmic Vision Program. It implements a space telescope to be launched at L2. The objective is to characterize the dynamics of the early Universe by using two instruments: the high definition camera VIS (visible instrument) and the spectrophotometer NISP (Near Infrared Spectrometer and Photometer). Light entering Euclid is either reflected toward VIS in the visible band, or transmitted to NISP in the infrared band by a dichroic mirror. In order to guarantee the quality of scientific data delivered by the mission, the knowledge of any chromatic dependence of the optical payload’s Point-Spread function (PSF) is critical. However, previous works showed that complex coatings, such as high-performance dichroic coating, are likely to induce high chromatic variations in reflection, either as a chromatic “Wave-Front-error” (WFE) and/or as inhomogeneous reflectance profile (R), both affecting PSF morphology. In-depth knowledge of the reflected wavefront by the Euclid Dichroic is then necessary in order to calibrate the in-flight Euclid Observations. This work focuses on two aspects. On the one hand, we present an experimental campaign to measure the dichroic WFE and R at any wavelength, incidence, and polarization state, with an extreme precision. This metrology work implements a bench funded by ESA, designed by Imagine Optic Company, and commissioned at LMA. On the other hand we build a numerical model of the dichroic based on these on-ground measurements. By reproducing the experimental optical properties of the dichroic mirror, we ensure the subjacent thinfilms physics at play is well understood, ultimately providing adequate inputs for the in-flight calibration of Euclid with a suitable level of accuracy.
We will present a new approach of linearized focal plane technique (LIFT), formerly developed by ONERA, which results in an improvement of a factor of 16 (4x4) of the spatial resolution. This technology is based on the combination of standard SH technology with phase retrieval algorithms applied on all spots of the microlens array that provides information on high spatial frequencies. We will show some measurements performed on extremely complex wavefronts. This technology presents very promising perspectives for optical and freeform metrology and can advantageously replace, at lower cost and better usability, Fizeau interferometry.
We will present a new approach of linearized focal plane technique (LIFT), formerly developed by ONERA, which results in an improvement of a factor of 16 (4x4) of the spatial resolution. This technology is based on the combination of standard SH technology with phase retrieval algorithms applied on all spots of the microlens array that provides information on high spatial frequencies. We will show some measurements performed on extremely complex wavefronts. This technology presents very promising perspectives for optical and freeform metrology and can advantageously replace, at lower cost and better usability, Fizeau interferometry : insensitivity to vibrations, multi-wavelengths compatibility, lambda/100 accuracy and a wide dynamic range are, in fact, intrinsic characteristics of this technology.
We report a compact adaptive optics (AO) module with optimized optical design and photon budget, compatible with multiple wavelengths, and adaptable to most of existing Light-Sheet setups, enabling a 2 to 3-fold signal improvement on neuronal structures of the live, non-clarified drosophila brain (neurons, projections), at depths ranging from 50 to 100µm. We report similar signal improvement brought by AO on functional signals from neurons of the drosophila circadian clock network. The proposed setup paves the way to fully automatized AO Light-Sheet systems usable in routine by biologists.
AO (Adaptive Optics) corrects wavefront errors to improve imaging quality in optical systems. An AO-system consist often of a SH-WFS (Shack–Hartmann wavefront sensor) and a DM (deformable mirror). The SH-WFS measures the local slopes of the wave front and iteratively calculates from these slopes the best fitting wavefront. The shape of the DM is then controlled by this information. Any error in the slope measurement (noise) will result in a residual wavefront error and hence in a reduced image quality.
The wavefront error detection method is based on the fact that the wavefront slopes have to be integrable and allows to quantify the error in the wavefront slopes measurement. The integrable wavefront derived from the measured slopes is used to re-calculate the slopes. The difference between the re-calculated slopes and the measured slopes is identified as the none-integrable noise of the slopes measurement.
The total noise is the sum of the integrable and the none-integrable noise. In order to derive a relation between the integrable and none-integrable noise 1000 measurements of the same wavefront have been taken. The average is assumed to be the noise free wave front. This wave front has been used to calculate the total noise of every single measurement.
Using this information an approximation of the total noise was found as: Total noise = None-integrable noise * 1.265.
This information can be used as an objective criterion for the quality of the wavefront measurement and to evaluate if the imagine performance is limited by the wavefront measurement or by the deformable mirror (e.g. number of actuator).
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