Day 23

Today I found an problem in the way my sort code worked, and the results of the laser might have been due to that error. However after fixing the code and clearing the workspace we had the same decrease in SNR, so we are sticking with the broadband source. I also stayed for some of  the REU's presentations including Klemens' who is in our lab. After that I worked more on organizing my code and the final presentation.

Day 22

In the morning today I worked more on my presentation and started commenting and organizing the code that I've done. We also had the presentations for tomorrow and friday today, which took up much of the morning.  The presentations are similar to what I've seen before with a few more slides of explanation and some of the recent work on the deformable mirror in there. During lunch we played cards which was fun. During the meeting Jie told me to do SNR calculations for the two sensors using the images. Aaron suggested that due to the weird values for the lasers, we should use broadband light which is coming in later this week.

Day 21

Today I focused mostly on the presentation due next friday. Tomorrow Zach and the REU students will be presenting to us and Jie through skype.

Day 20

Today in the morning we presented our outlines. In my case, as I had expected, my outline had too much stuff in it to go into the amount of detail I would need to explain things, so I cut out a lot of the things that I have been doing in the past few weeks.

Once I got to the lab, I continued working on the slope code until lunchtime where me and a few other interns played soccer. After lunch I finished up the code for the wavefronts and also managed to write and process code for data I took comparing tilt to SNR. For that code we found (as we expected) that the SNR doesn't really vary for different tilts.

Updated Abstract

Analysis and Comparison of the OD WS and the Shack-Hartmann sensor.

The purpose of Adaptive Optics is to calculate and correct random light distortions. In order to determine the accuracy of a wavefront sensor and compare different wavefront sensors, the signal to noise ratio (SNR) can be calculated to see how much of the original image was preserved. The Optical Differentiation sensor is a newer sensor that can be adapted to many different wavelength ranges and works with multicolored light sources.   By comparing the SNR of the Optical Differentiation sensor to the industry standard (Shack-Hartmann) sensor we can determine how competitive the Optical Differentiation sensor is. Finally the current numerical model for the Shack-Hartmann sensor presented in a paper by Oti only offers an upper bound equation for the SNR, so other terms were researched in order to have an equation that better fits the simulation results in the same paper.

Updated Outline

• Title Slide
• Summary
• What is going to be discussed in the presentation
• Larger project and Deformable mirror
• To develop a sensor to compete with the Shack-Hartmann
• Basics of wavefront sensing
• what a wavefront is,
• Purpose of what I am doing
• What is an optical differentiation sensor
• diagram and explanation
• prototype
• Comparison between OD and Shack-Hartmann sensor
• OD has better dynamic range, can look at polychromatic sources
• Important to make sure quality of image is the same
• Explanation of Signal to Noise Ratio
• Important to compare different sensors
• Shows how much of original image is preserved
• Equation for the SNR of OD and SH sensor
• From paper by Oti
• Explanation of terms
• Derivation
• Numerical calculation of SNR of both sensors
• Estimation for number of photons and ensemble average
• Actual calculation
• Analysis of numerical calculation
• Oti Graph
• Difference in Airy rings
• Atmospheric turbulence term for Shack-Hartmann sensor
• Graph and explanation
• Centroid error term for Shack-Hartmann sensor
• Graph and Explanation
• SNR of camera for broadband
• graphs and analysis
• SNR of camera for lasers
• graphs and analysis
• Analysis of camera SNRs
• Conclusion    

Day 19 Blog

Today in the morning I took measurements with the Shack-Hartmann wavefront sensor. The rest of the morning was spent working on the code. For the Shack-Hartmann sensor I need 3 different code parts. One to analyze the the intensity data, the other to measure the position data and the final (and hardest) is one that takes the centroid data, does a bunch of stuff to it to get the displacement data, then uses that to get the wavefront slope data.

At 11 all of the interns took a bike ride to U of R and ate lunch there before coming back to RIT around 1:30. The bike ride was a lot of fun and a good way to interact with the other interns.

After the bike ride I went back to coding and finished the position code and started the slope code.