BMC’s deformable mirror (DM) technology is used as the central component in the WS-AOD-B to compensate for phase aberrations. The BMC DM is a continuous facesheet deformable mirror that is controlled by hysteresis-free electrostatic actuators located on a square grid. The full DM active aperture can be as little as 1.5 mm to as much as 25 mm across. Each actuator can provide up to 5.5 µm of mechanical stroke, which corresponds to about 11 µm of phase control. The electrostatic actuator array is driven using independent high voltage channels with 14-bit resolution. This corresponds to sub-nanometer displacement precision. The drive electronics can provide frame rates of from about 4.6 kHz up to 100 kHz.
By utilizing the included algorithm to manipulate the mirror surface, the mirror compensates for aberrations and converges to an optimal profile. The user has access to the open source code to balance correction capability between maximum signal and minimal time. The system is intended to serve three main purposes:
Introduce: Serve as an introduction to wavefront sensorless adaptive optics principles. By using the system in its current form, the user is able to understand the details involved in properly implementing a metric-based adaptive optics solution on an optical system.
Utilize: Use the demonstrator as a stand-alone aberration compensator. The user can utilize this system on its own to correct for aberrations inserted into the optical path. By introducing aberrations in the sample stage, the system can be optimized for a multitude of uses ranging from laser research applications to scanning laser microscopy.
Integrate: Enable integration of the components into an existing optical system. The user can integrate the hardware into an existing optical system and utilize the open source software code for metric-based correction.
A complete solution for laser-beam shaping applications. The Wavefront Sensorless AO Demonstrator - Beam Shaping (WS-AOD-B) provides a platform utilizing metric-based wavefront control with BMC MEMS DM technology. While conventional AO systems perform closed loop DM control using direct measurement of the wavefront as feedback, the metric-based approach uses details in the aberrated light to improve clarity. The system is configured to use a hill climbing algorithm to compensate for wavefront phase errors.
NOTE: This demonstrator has been discontinued. However, we are currently integrating its capabilities into a new adaptive optics software development kit. Stay tuned for more information early in 2018.
The Wavefront Sensorless AO Demonstrator-Beam shaping is a fully-customizable instrument. BMC can tailor the system for researchers and scientists with existing setups and applications. Please contact us to discuss how the WSAOD-B can be customized for you.
The WSAOD-B is currently only available as the Fundamentals kit. This Includes the data acquisition board and software.
We can provide a list of components that can be easily purchased through our partner, Thorlabs Inc., in order to complete the entire kit.
WSAOD-B Standard Components:
- BMC deformable mirror
- Photodetector data acquisition board
- Monochrome CCD camera
- All optical components for system including lenses, mounts, translation stages, irises, etc.
The control software for the Wavefront Sensorless Adaptive Optics Demonstrator-Beam Shaping is open source code based in Mathwork’s Matlab, Release 2007a, and runs on platforms using Windows operating systems. The software interfaces with the deformable mirror drive electronics and CCD camera via a USB 2.0 connection, and the photodetector data acquisition board via the PCI bus. The software allows the user to correct for aberrations introduced as well as generate a random aberration using the DM. The interface consists of the standard Matlab entry screen as well as a live image of the CCD camera signal and plot of the previous system convergence. The closed-loop frame rate measured for the system using the hardware and layout described with a Multi-DM system is 720 Hz.
The demonstration system also includes a Thorlabs DCU223M monochrome CCD camera to image the point-spread function of the focused beam. The camera-to-PC interface is a USB 2.0 connection, providing full resolution images (1024 × 768 pixels) at a frame rate of 30 Hz.
Measurements of the on-axis intensity metric used by the controller are performed using a Thorlabs PDA36A silicon photodetector. The pinhole used to sample the on-axis beam intensity is placed directly above the active photodetector area. The photodetector output voltage is acquired using a multifunction measurement board that is configured to read a single-ended analog input channel with 12-bit resolution. The board interfaces with the PCI bus of a standard PC and communicates data to the system control software at an average data rate of 6 kHz.
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