High precision damage-resistant multiple-pass ultraviolet reflectometer

Conference · Sun Jan 01 04:00:00 EST 1984

DOI:https://doi.org/10.1520/STP23110S· OSTI ID:6461712

Jolin, L J; Foltyn, S R

A multiple-pass cell was reported by John White in 1942. Since them, it has been adapted for use as a high-precision reflectometer. The multiple-pass reflectometer has been studied and reported by Arnon and Baumeister. Here, a reflectometer which is similar is described. It utilizes a uv laser operating at lambda = 351 nm as the source and the White-cell mirrors are high-reflection dielectric coatings designed for that wavelength. Because of the low-loss reflectors used in the cell, a high number of traversals, reflections, can be achieved; R greater than or equal to 239. The use of dielectric mirrors also improves the damage resistance of the apparatus which is important when a uv laser beam is used. The results of reflectance measurements performed on several ultraviolet high reflectors are also reported. These include conventional dielectric coatings as well as a hybrid coating consisting of Al/sub 2/O/sub 3/, HfO/sub 2/, and SiO/sub 2/ layers. The Los Alamos optical damage laboratory has observed and defined several types of laser-induced damage to optical materials. In the case of high reflection, multi-layer, dielectric coatings, damage may be defined as any change in the coating layers or at the substrate interface which causes a measurable change in reflectance at its design wavelength. Since most dielectric high reflectors have reflectances approaching unity, and a change caused by laser irradiation can be minute, a precise method for measuring high reflectance must be utilized. A multiple-pass reflectometer based on the White cell was selected because of its demonstratd precision and high accuracy. It utilizes a laser as the source for reasons described later.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6461712
• Report Number(s): LA-UR-85-3734; CONF-8410186-5; ON: DE86002443
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
440300 -- Miscellaneous Instruments-- (-1989)
47 OTHER INSTRUMENTATION
COATINGS
DESIGN
DIELECTRIC PROPERTIES
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
MATHEMATICAL MODELS
MEASURING METHODS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
REFLECTIVE COATINGS
REFLECTIVITY
SURFACE PROPERTIES
ULTRAVIOLET RADIATION