Adaptive scanning optical microscope (ASOM): large field of view and high resolution imaging using a MEMS deformable mirror

Abstract

For a wide range of applications in biology, medicine, and manufacturing, the small field of view associated with high resolution microscope systems poses a significant challenge in practice. This paper describes an optical microscope design, called the Adaptive Scanning Optical Microscope (ASOM), which uses a MEMS deformable mirror working with a specially designed scanning lens to achieve a greatly expanded field of view. Most adaptive optics systems (e.g. telescopes and ophthalmology instruments) are designed to achieve near ideal performance under nominal operating conditions and primarily use the adaptive optics element to compensate for a time varying disturbance to the wavefront that is external to the optical system. In contrast to this approach, the deformable mirror in the ASOM is an integral component of the optical system and the static (glass) optical elements have been specifically designed to match the shape correcting capabilities of the deformable mirror. Using a high speed steering mirror coordinated with the deformable mirror actuation voltages, the ASOM operates by scanning over the workspace and should achieve diffraction limited imaging over a region approximately two orders of magnitude larger in area than a traditional microscope design. With the rapid scanning capabilities allowed by the high speed steering mirror and by acquiring a complete image during each exposure, the ASOM offers advantages in dynamically reconfigurable and adaptable imaging with no agitation to the workspace. After describing the design and operating principle of the ASOM, we present results from a low cost ASOM prototype.

Image Tracking of Multiple C. Elegans Worms Using Adaptive Scanning Optical Microscope (ASOM)

“…Consequently, the light coming out of the deformable mirror is nearly aberration free. After passing through the pupil relay optics and being projected onto the science camera, the image quality is near the diffraction limit (Potsaid et al 2007b). A low cost ASOM prototype built with off-the-shelf optics is shown in Figure 3.…”

“…In previous work (Potsaid et al 2007b), a digital controller is designed to reduce the long settling times and steady state error that resulted from using a stock analog controller. The digital controller is implemented using xPC Target from MathWorks as the real-time operating system, and MATLAB/Simulink as the development environment.…”

“…This prototype has been used to prove all essential aspects of the ASOM concept, and it is utilized to perform the experiments described here. The components of this prototype are listed below (Potsaid et al 2007b). …”

Wide Field Scanning Telescope Using MEMS Deformable Mirrors

“…Different deformable mirrors also have varying rigidity in the mirror surface materials, causing different mirror shapes under the same actuator voltages. We therefore use a gradient ascent method based on the sharpness metric (as in Potsaid and Wen 2008). The basic algorithm for the actuator voltage update is…”

“…Because of the unpredictable external conditions, a natural or manmade reference point source, or guide star, and a wavefront sensor to measure the aberration of this point source, are needed to measure and then correct for the wavefront aberrations. For a scanning telescope, the aberrations are due to the optics intrinsic to the telescope, and therefore can be pre-computed or calibrated for correction without the guide star nor wavefront sensing, similar to our scanning microscope concept, called the adaptive scanning optical microscope (Potsaid et al 2005(Potsaid et al , 2009Potsaid and Wen 2008), which uses a MEMS deformable mirror to expand the field of view in microscopy.…”