The development of precise laser machining using an ultraviolet laser such as an ArF excimer laser enhances the requirement for transmittance or reflectance measurements of optical parts in the deep ultraviolet region.
The SolidSpec-3700DUV enables measurements in the range from 175nm to 2600nm with an integrating sphere, and in the range from 165nm to 3300nm by mounting the optional Direct Detection Unit DDU-DUV. With this additional unit, the wide range from deep ultraviolet to near-infrared is now measurable.
Oxygen molecules in the atmosphere absorb ultraviolet light under 190nm. Nitrogen gas purging for both the optical and the sample compartment is required to remove the interfering oxygen molecules. Since the SolidSpec-3700DUV has purge inlets for each compartment, high throughput nitrogen gas purge is possible, and high sensitivity with lower stray light in the deep UV region is achieved.
Materials that do not absorb deep ultraviolet light are required to be used as the window material for the detector and the coating material for the inside of the integrating sphere to enable performance in the deep ultraviolet region. The Solidspec-3700DUV uses a PMT detector with fused silica as the window material and an integrating sphere with resin that has highly reflective characteristics in the deep ultraviolet region as the inside coating material.
High sensitivity and lower stray light measurement in deep UV
In order to perform high-accuracy measurements in the deep UV region, a sufficient quantity of light and significant low stray light are required. The transmission spectrum of a silica plate measured with the Direct Detection Unit DDU-DUV (option) is shown in the right figure. Spectra with significantly lower noise are obtainable in the ultraviolet region.