Plasma treatment apparatus

A plasma treatment apparatus, comprising:

• a chamber defining a processing inner chamber, wherein a top portion of the chamber has a window;
• a planar plasma-generating electrode located in the processing inner chamber for generating a planar plasma;
• a sample suspension and holding system disposed in the processing inner chamber opposite to the planar plasma-generating electrode for suspending and holding a sample, wherein the sample suspension and holding system comprises:
• a clamping member;
• and
• a first adjustable suspension member connected to the clamping member;
• and
• an optical observation system located in the processing inner chamber adjacent to the sample suspension and holding system to measure a thickness range of an effective influence region of the planar plasma through the window of the chamber, wherein the optical observation system comprises:
• an observation lens comprising a transparent substrate, a shelter coating located on a surface of the transparent substrate, and a fluorescent coating located on the shelter coating;
• and
• a second adjustable suspension member connected to the observation lens for suspending and adjusting a height of the observation lens in the processing inner chamber.