FourierOpticsJHU2021

Anand Sivaramakrishnan, anand@stsci.edu Laurent Pueyo, pueyo@stsci.edu

https://JHUBlueJays.zoom.us/j/8512987178?pwd=cVhLMUtPaCs3MlNseE51ajRqOUhiQT09

First class 1:30-2:45 pm Tuesday Aug 31 2021, Bloomberg 511. We will arrange a double slot that suits everyone then, and meet once a week from there on. The first class will likely not last the full period.

Course Content

We focus on the practical application of Fourier transforms in modern observational astronomy. Fourier transforms provide a framework for understanding much of astronomical instrumentation and its observational methods: imaging cameras, spectrographs, coronagraphs, interferometers, time-series analysis, correlation methods, filtering, and many object detection methods. We will treat direct and synthetic imaging, discussing instruments that span the electromagnetic spectrum from radio to ultraviolet.

Course requirements

Textbook

1. The best textbook for this class is still:

   R.N. Bracewell, "The Fourier Transform and Its Applications" (Third Edition, Mcgraw-Hill, 2000).

   This book is unfortunately out of print and has been so for some time. The remaining stock is expensive. If you can find a copy somewhere, borrow it, or buy it second-hand if you can. This book is very good, and former versions of this class used it extensively. If you can obtain a copy in any format it will be a valuable reference for you in the future. A DJVu format is best. (I use DjVuLibre DjView to view it on OS X Big Sur and older OS X's). Some assigned reading and problem sets will come from this book.

2. Some useful background papers on interferometry:

   John D. Monnier & Ronald J. Allen, "Radio & Optical Interferometry: Basic Observing Techniques and Data Analysis".

   This is Chapter 7 of Volume 2 from an (outrageously) expensive anthology titled "Planets, Stars and Stellar Systems", published in late 2012 by Springer. Our chapter treats interferometry both in optical/IR astronomy and in radio astronomy from a unified viewpoint, focusing on the physical foundations and the corresponding practical issues that beginning researchers need to know. Available free as an astro-ph preprint

   Optical Interferometry in Astronomy is Monnier's summary of non-redundant masking (closure phases, closure amplitudes, etc.).

3. "Principles of Optics" M. Born & E. Wolf, 1975 (Pergamon). This book is the bible for physical optics. Several editions exist. Even the older editions have all the basic material you are likely to need. You do not need to buy it.

4. "Introduction to Fourier Optics" J. W. Goodman, (McGraw-Hill, second edition, 1996) (expensive). More formal in the math. I have a copy if anyone wants to borrow it for a week or two.

5. "Interferometry and Synthesis in Radio Astronomy" A.R. Thompson, J.M. Moran, & G.W. Swenson, (Springer, 2017). This is the bible for the subject as applied to radio astronomy. PDF downloadable via the link above. Details on radio interferometry - closure quantities, calibration, image reconstruction. Newer techniques have been added to the latter.

6. Articles: Mostly via the Astrophysical Data System ADS which points to free Arxiv versions when they exist.

Course structure:

This course meets weekly. If you are taking this course for credit, regular attendance and in-class participation is expected. Unavoidable absences (such as observing runs) should be discussed with us beforehand.

Grade

There will be no tests and no final exam for this course. Your grade for this course will be determined by equally weighted contributions from:

• Participation in the discussion of the problem sets attempted before class
• Turning in homework post-discussion
• Oral presentation and term paper

Problem sets and assigned reading - homework first, lecture second

(We can change this for 2021 class - I just copied this section as well)

In the earlier part of the course we will assign problem sets and/or reading that must be attempted and/or done ** before the next class **. The goal of your reading is to acquiant you with the relevant ideas, framework, vocabulary, and formalism. The problems then give you an opportunity to try working these before the lecture.

1. Attempt every problem before class. This prep work is essential for the ** in-class discussion amongst yourselves and with us** early in the class. Air your confusion/clarity on concepts and details, and help each other. Discussion is part of learning in the class.

2. Complete your homework and turn it in by the start of the following class (email to ** jhu.fourier@gmail.com ** or hardcopy). Before class ends we will assign the pre-class homework for the following class, until we drop homework for your term paper preparation.

Term Paper and Oral Presentation:

A term paper is required. Topics will generally be taken from the historical/research literature on coronography, interferometry, and aperture synthesis in radio and optical astronomy. You may suggest your own topic. The subject matter must be approved by Anand and Laurent.

Choose your topic early in the class; first full drafts are due before the Thanksgiving break, and ought to be 4 - 5 pages long (single-spaced) plus figures. You may use any text processor/formatter you please, but if you have no preference, use LaTeX2e with a "class" file from one of the common astronomy journals (e.g. aastex.cls).

A stand-up presentation on the topic of your term paper is required. You will have about 30 minutes to present and respond to questions from the audience. We will do this in the last class.

** Start discussing topics as early as possible **

Term paper milestones (week starting on dates below)

• Topic with suggested section titles
  • Due week of Class #4. Sep 20.
  • What is the tie in to course matter? E.g., Appropriate survey/new ideas?
  • Potentially publishable? (start discussing early)
• Rough draft 2-3 pages
  • Due week of Class #6. Oct 04.
  • Demonstrate relevance, feasibility
  • Almost final section definitions, section entries with substance/detailed plan
• First full draft submission, 4-5 pages. Nov 19.
  • Before Thanksgiving break
• Final paper due at presentation. Nov 29.

Class Schedule

Mondays of the week are used here - in the first scheduled class we decide on which day of the week we meet for 2h 30 min (with a short break in the middle) We will have a couple of guest lectures from active specialists.

2021 classes are on Tuesdays!

Week starting	Class#	Notes	Topics	Homework
Aug 31	#1	Anand	Course structure, meeting date, martixdft & hcipy, pocket interferometer, coherence, FT defs	upload, run a test DFT, testhcipy
Sep 06	#2	Laurent	Justify Fourier transform, using sky-telescope aperture	dft:sampling, aliasing, numpix variation,... , prep for Fourier thms show&tell
Sep 13	#3	Laurent	Image formation for 'one dish' telescope	?
Sep 20	#4	Anand & Laurent	Fourier familiarization - principle of coronagraph. Recap of path to Fourier optics. Term paper topics this week.	Vortex coronagraph student show and tell prep., Labeyrie interferometer numerical example?
Sep 27	#5	Laurent	Interferometry, Monnier&Allen eq 1	Measure angular size of Vega
Oct 04	#6	Anand	Nulling interferometers, perfect coronagraphs, speckle formation and noise	student CoDR reviews of BLC, FQPM, Self-coherent, vortex,
Oct 11	#7	Anand	Speckle, speckle pinning, non-linearities, SFWFS, symmetries in FT	Exercise phase bump nb, present your experiments verbally in class
Oct 18	#8	Anand	AO, Wavefront sensing, defocus, Shack-Hartmann, Missell-Gerchberg-Saxton, GSGS, Electric field conjugation	Prove "twinning problem" ambiguity on paper, install CASA and test it
Oct 25	#9	Anand	uv coverage exploration, complex visibility, analytical monochromatic fringes, closure phases, calibrating interferometric observables. The Martinache algebra of NRM/kernel phase.	Work on final draft of term paper
Nov 01	#10	Melissa Hoffman (STScI) and Peter Teuben (UMD)	Radio interferometry with ALMA: synthesis imaging, wide field mosaicing	Prep: Install CASA and sample data, bring laptops. Deliver final draft of term paper
Nov 08	#11	Jens Kammerer (STScI)	NRM and Kernel phase interferomtry	Polish/fix term paper
Nov 15	#12	Laurent	TBD
Nov 24			THANKSGIVING
Nov 29	#13	Class	Term paper presentations

On-line course evaluation: NEEDS UPDATING.

The 2018 class used:

From: ASEN Course Evals <ASENCourseEvals@jhu.edu>
Date: Monday, November 19, 2018 at 12:05 A
Subject: Teacher Course Evaluations are Now Available for Fall 2018 Term!

Fall 2018 teacher course evaluations are now available for your students to complete online. They will receive an email asking them to complete a short 10-15 question survey for each of the following courses in which they are enrolled:

- Any Arts & Sciences (AS) course section with a minimum enrollment of at least 5 undergraduate students. All AS independent study, research, and internship based courses are excluded regardless of the number of students enrolled.

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Each evaluation should take approximately 5-10 minutes to complete.

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