For Physics 126 you will need two items, a lab notebook
and the textbook.

The lab notebook should be bound, with numbered pages
having a grid.  You will turn in photos or scans of
the notebook pages.  I suggest at least 100 pages.
Here is an example:

   https://www.amazon.com/dp/0978534425/

You may use an electronic alternative for your notebook,
but if you do this, you must choose a program that allows
you to make drawings and submit your notebook as a PDF
file with properly numbered pages.

The textbook for Physics 126 is:

   Introduction to Optics, 3rd edition
   ISBN 1108428266 (978-1108428262)
   Cambridge University Press
   By Frank L. Pedrotti, Leno M. Pedrotti, and Leno S. Pedrotti
   https://www.amazon.com/dp/1108428266/

The Pedrotti book is comprehensive, and at a good level
for upper-division undergraduates.  Unfortunately it has
gotten more and more bloated with each new edition.

Two other books you may find helpful:

   Optical Physics, 4th edition
   ISBN 0521493455/978-0521493451
   By Ariel Lipson, Stephen G. Lipson, and Henry Lipson  
   Cambridge University Press
   https://www.amazon.com/dp/
   https://www.amazon.com/dp/0521493455/

This is at a higher level than the Pedrotti book, and discusses
more modern topics.  It is an excellent reference, but you will
probably not find it necessary for the course.

If you need a refresher on error propagation and analysis,
this book is excellent:

   An Introduction to Error Analysis:
      The Study of Uncertainties in Physical Measurements
   ISBN 1940380081 (978-1940380087)
   3rd Edition
   By John R. Taylor
   https://www.amazon.com/dp/1940380081/