SBIR Phase I: Laser-Based Replacement for FTIR Microscopy

This Small Business Innovation Research (SBIR) Phase I project will identify the issues to be solved in order to build a prototype quantum cascade (QC) laser-based infrared microscope. Infrared microscopy holds great potential as a medical diagnostic tool. Present microscopes are based on Fourier transform infrared (FTIR) spectrometers and cooled detectors. The cost and slow speed of these FTIR microscopes limits their usefulness in standard medical clinic settings. New QC laser technology makes compact, broadly tunable laser light sources a reality for the mid-infrared region (3 to 12 um), a spectral region rich in features for cellular diagnostics. The high power of these lasers makes it possible to use less sensitive room temperature focal plane arrays (FPAs) for image acquisition. The research objectives are to couple broadly tunable QC lasers to an infrared microscope, and then use a microbolometer FPA for image acquisition. The research will explore the issues of coupling coherent laser light into a microscope core, including optomechanical design and the effects of laser speckle on image acquisition. Data acquisition and laser illumination issues will be tested with initial coupling into a microbolometer FPA. The broader impact/commercial potential of this project is that infrared microscopes with increased capabilities and reduced cost can be developed, such that they will become widely available for medical diagnostics at the clinic level around the world. This in turn would make cellular diagnostics, particularly for cancer, more readily available to aid in catching and treating cancers at an earlier stage. By coupling room temperature lasers and FPAs to infrared microscopes, it should be possible to reduce the size, energy consumption, and cost of these instruments. In addition, FTIR microscopes require cooled mercury-cadmium-telluride (MCT) FPAs for full image acquisition, which are export controlled by the U.S. Department of State. Therefore, most FTIR microscopes use limited linear arrays, which greatly reduce their speed of image acquisition since rastering is required. The microbolometer FPAs that can be used with QC laser sources are not export controlled, so full image acquisition will be possible in a broadly available commercial instrument, increasing the speed of acquisition while reducing cost and removing the need for cryogenic cooling.