The phrase "an extended reflection" is correct and usable in written English.
It can be used when discussing a thorough or in-depth consideration of a topic or idea.
Example: "In her essay, she provided an extended reflection on the impact of climate change on global ecosystems."
Alternatives: "a detailed contemplation" or "a comprehensive analysis".
It is an extended reflection on lives that begin hopeful and turn dark.
Penelope Lively in the Financial Times described it as "an extended reflection on the fear of death and on that great consolation, religious belief.
In the second, the world premiere of Alexander Raskatov's Green Mass, an extended reflection on our generation's continuing sins against the natural world.
In addition to passages about pets and bodybuilding, Musharraf delivered in the book an extended reflection on the nature of command, in which he relied upon quotations from Richard Nixon's neglected tome "Leaders".
Instead, Jennens's text is an extended reflection on Jesus Christ as Messiah.
As its title indicates, the book explores the gruesome misdeeds of a murderer (and rapist), but it is also an extended reflection on how and why one might write about, and even befriend, such people.
Nor does the term "belief", in standard philosophical usage, imply any uncertainty or any extended reflection about the matter in question (as it sometimes does in ordinary English usage).
A more extended reflection on them seems called for, however, especially a reflection on Dedekind's "logicism" and "structuralism".
In the second chapter, called "Transreading" (the author's penchant for "poetic" diction like this is an irritating tic; you get "Lifeleading" and "Wifewishing" too), Gass the critic makes himself felt in a brilliant extended "reflection on the problems of translation".
49, 50 Fluorescence detection of Alexa 647 was done using a dichroic mirror with extended reflection (Chroma, Z660DCXRU) and a bandpass emission filter (Chroma, ET700/75).
Fluorescence detection of Alexa 750 also used a dichroic mirror with extended reflection (Chroma, Q770DCXR) and a bandpass emission filter (HQ800/60).
