In late 2010, the CBC Machine Shop was asked to design and build a Variable Angle Light Reflectance Module (VALRM) that could be used with a faculty member’s existing Vertex FT-IR Microscope. The science behind the VALFR is part of a patent being devloped by Dr. Karl Booksh of the Chemistry Department. The mechinical design aspect of the project was placed in the hands of the CBC Machine Shop to develop.
The limitations of the design were as follows:
- The module must fit inside the existing spectrometer opening
- The rotating mirrors must move in concert with each other with little to no backlash
- The cradle for the prism must be able to be adapted to fit various prism geometries
- There had to be an idicator which display the precise angle of the rotating mirrors
- Although initially rotating the mirrors would be done manually, the ability rotate the mirrors via servo motor must be built in
Nicola Menegazzo, Post-Doctorate for the Booksh Group, describes the scope of the project as:
“This mirror bench has been custom designed for the Booksh group to permit surface plasmon resonance (SPR) spectroscopy with conventional Fourier-transform infrared (FT-IR) spectrometers. SPR is a technique typically used in (bio)analytical chemistry to obtain information about biomolecular systems, like protein-protein interactions. The sensitivity of this technique to surface binding events has led to its widespread utilization for biosensing applications.
SPR is most commonly performed in the visible range of the electromagnetic spectrum, which is ideal for studying surface events, but is limited when unconventional substrates are used. Accessing longer wavelengths is crucial for characterization of novel plasmonic materials or nano- and micro-structures. This mirror bench was specifically engineered to integrate into conventional FT-IR spectrometers and enable IR-SPR analysis in a simple, compact platform. The flexible design accommodates interchangeable refractive optics, for improved compatibility with the different spectrometer manufacturers and analysis type, as well as a high precision incident angle selection mechanism, necessary for analysis with IR wavelengths.”
*Update* – Recently, a paper describing the development and implementation of this “mirror bench” accessory entitled Adaptable Infrared Surface Plasmon Resonance Spectroscopy Accessory was published in the Review of Scientific Instruments.