The most important part of any adaptive optical system is a deformable mirror. One of the most widely used type of such mirrors are the bimorph ones. In fact, there is no problem to manufacture a wide aperture bimorph wavefront correctors that perfectly can compensate low-order laser aberrations. But if one needs a tiny deformable mirror to correct for high order aberrations with reasonable amplitude, he usually will use stacked actuator mirror or a MEMS one. In this presentation we suggest the new design and technology of production of a small size bimorph mirrors to be used to correct for atmospheric phase fluctuations. Our mirror has the diameter of 30 mm and 37 control electrodes (mirror with 20 mm and 63 control electrodes is being developed). The resonance frequency of 13.2 kHz is due to its small diameter. At the same time, large number of electrodes allows to reproduce high order aberrations. To manufacture this device two modern technologies are used: ultrasonic welding and laser engraving technology.
As it is well-known, the laser radiation, propagated through different mediums, is affected by wavefront distortions and thus the quality of the radiation is significantly decreased. To compensate for the wavefront aberrations adaptive optics means are used. We developed miniature bimorph mirror with 37 electrodes. To manufacture this type of mirrors two technologies were used. Those are laser engraving technology for drawing electrode grid on the piezoceramic disc, and ultrasonic welding technology to connect wires to the control electrodes. Main parameters of such a deformable mirror were investigated and presented in this paper.
The correction of the laser beam aberrations and the formation of the laser beam intensity is very important scientific task. This problem widely is being decided at this moment. The employment of the bimorph deformable mirrors for this kind of applications is very promising. But this type of the wavefront correctors has one reasonable shortcoming – low spatial resolution of the control electrodes, it doesn’t allow to compensate for the high-order wavefront aberrations. This kind of aberrations is valuable for imaging applications, mainly if needs to reconstruct specific details. Therefore, we have to use the wavefront correctors with high spatial resolution of the electrodes. In this work we present two types of the bimorph deformable mirrors for solving this problem – multilayer bimorph (multimorph) mirrors and bimorph mirrors with high density of the control electrodes. To place high number electrodes on the piezodisk the laser engraving technology was used, and ultrasonic welding technology used to make the wire connection to these electrodes. We developed the powerful numerical model to simulate bimorph mirrors.
Formation and correction of the given laser beam intensity and phase is an important practical and scientific problem. Semipassive bimorph flexible mirror is one of the most widely used devices for this purpose. But the key disadvantage of these kind of mirrors is their low spatial resolution of the corrected phase. Mainly this problem occurs when one deals with the small aperture wavefront correctors. In this work we present two approaches to overcome this problem – one to use a multilayer bimorph (multimorph) mirrors and another to put higher density of control electrodes and use a special technique (ultrasonic welding) to make the wire connection to these electrodes. Here we also present a numerical model to simulate bimorph correctors, based on a variation approach of the finite elements method.