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Department Library

2020

Carter Day (Senior Thesis, June 2020, Advisor: Richard Sandberg )

Abstract

Here I present a study on the effect of "large" three-dimensional objects in Interference Pattern Structured Illumination Imaging (IPSII). Due to the nature of the IPSII method, objects with a lot of depth in the imaging field create "shadows" or areas where the structured illumination fails This is because IPSII's structured illumination may be projected at a given angle θ from the object normal. These shadows are characterized by the absence of interference, not always the absence of light, and cause blurring around edges in the resulting image. The more depth an object has, the more fringe effects appear in the resulting image. This thesis reviews simulations that capture this reduced interference and therefore breakdown of IPSII due to shadowing. Also, initial experimental results are presented in an effort to demonstrate this effect. Finally, a discussion of what next steps should be taken is presented.

Dallen Petersen (Senior Thesis, April 2020, Advisor: Richard Sandberg )

Abstract

A simple, low-cost, high-precision, motorized mirror controller is presented that was developed for use in a lensless imaging experiment. The goal was to achieve angular precision of better than 20 arc seconds while costing less than comparable commercial options. This is done using a standard kinematic mirror mount, high-pitch screws and stepper motors held together by 3D printed parts. The mount can be controlled by a python script on a Raspberry Pi or any other microcontroller connected to the motors. The mount can be quickly assembled for less than \$350 and achieves a large angular range (10 degrees). The accuracy is tested using a laser reflected off of a mirror controlled by the mount and projected onto the CCD of a webcam. The tested accuracy was 7.67 arc seconds with a standard deviation of 4.71 arc seconds.

Benjamin Whetten (Senior Thesis, April 2020, Advisor: Richard Sandberg )

Abstract

A lensless imaging method known as Interference Pattern Structured Illumination Imaging (IPSII) is discussed. Because it does not require a lens, IPSII has a higher theoretical resolution limit than traditional optical microscopes. However, the quality of IPSII images is currently limited by mechanical noise in its mirror movements. This thesis characterizes the resulting distortions caused by uncertainty in IPSII mirror movements. To do so, a model is presented that simulates the propagation of mechanical noise in the experimental IPSII setup to the resulting image data. It is shown that this noise causes errors in both the phase and amplitude of the Fourier transform of the image. Finally, a method to partially correct the resulting image distortions using phase retrieval algorithms in presented.