Astronomical Telescopes and Instruments 2020
As of 2019, Leiden University does not want me to make my lectures available publicly anymore. Students who take or took a course can find the lecture materials on Brightspace.
Link to official course
Field Guide to Astronomical Instrumentation, by C.U.Keller, R.Navarro, B.R.Brandl, published by SPIE, available at spie.org/Publications/Book/2064990
Optics, 4th edition, by Eugene Hecht, published by Addison Wesley, available at book stores