Adaptive optics is an advanced technology, and its correct appliucation requires a lot of "know-how". Here, we share some of our knowledge which is a result of more-than-a-decade experience.
Direct control of Zernike modes is beneficial in feedforward control algorithms, and in optimization-based adaptive optics, such as laser intracavity AO, adaptive image sharpness control, smart PSF control in microscopy, optimal imaging through turbulence with stochastic optimization, etc. In all these cases the dynamic control of Zernike modes provides for very quick quasi-optimal convergence to the maximum value of the target function.
Here we show a 15 mm 37-channel OKO Micromachined Membrane Deformable Mirror (MMDM) and 30 mm 37-channel Piezoelectric Deformable Mirror (PDM) operated by Zernike polynomials in feedforward control mode. No wavefront sensor is used during the mirror operation. Both mirrors are controlled by our free MiZer software.
What is the maximum defocus correction I can get with your mirror? Is it possible to generate both negative and positive defocus? Which mirror, PDM or MMDM, do you advice me to use for correction of Z2,0? — Here, at Flexible Optical, we receive quite often these questions. This short article explains the aspects of the generation/correction of the defocus aberration with MMDM and PDM and considers the factors limiting the amplitude of the correction with various types of mirrors.
18-channel PDM has no actuators inside the active aperture. This makes it suitable for an excellent correction of low-order aberrations. The note presents interferometric images of the results of the generation with the 30-mm 18-channel PDM.