The fourth edition of FLAIR, Field Laser Applications in Industry and Research, was held on May 5 until May 9, 2014, in Pratolino, Firenze, Italy, the same venue where the FLAIR series was started in 2007. The enthusiasm for this edition has been dampened by the sudden passing of Dr. Peter Werle, one of the two co-chairmen, on September 6, 2013, during the organization of the meeting. For an obituary of Dr. Werle see [1].This event obviously affected the organization of the Conference, including its schedule. We wanted to pay Peter Werle a special tribute, but in such a way to transform this remembrance into a positive event. To this end, the conference began with a special session that not only highlighted Peter Werle as a great colleague and friend but also as a visionary who has made numerous significant contributions to quantitative analysis, including noise analysis, employing tunable IR spectroscopy.Dr. Werle was the first to introduce the Allan variance concept [2] to spectrosco ...