Our work in the optical and mechanical design of computational spectral imagers has been targeted towards fluorescence microscopy applications. We have been involved with the design of both a pushbroom system (SmacM) and a snapshot system (MacSim). The pushbroom system is based on a static aperture coded single disperser design that is translated in order to capture a 3D cube (2D spatial, 1D spectral). The snapshot system, however, is a dual disperser architecture which uses advanced signal processing techniques (compressive sensing) to measure a 3D cube in a snapshot.
Scanning multiplex aperture coded microscopy (SmacM)
SmacM evolved as an extension to our high throughput aperture coded spectrometer designs for Raman chemometrics. A high throughput aperture coded spectrometer is placed at the intermediate image plane of a microscope. The spectrometer is scanned perpendicular to its dispersion direction. Scanning the spectrometer creates a 3D cube (2D spatial, 1D spectral) of any given scene placed at the object plane to the microscope. Compared to a conventional pushbroom system, the aperture coded system has 32 times greater throughput.
Two systems were designed: the first design had a spectrometer placed at the intermediate image plane of a lab built microscope housed in a rapid-protyped case. The second design consisted of an aperture coded spectrometer placed at the intermediate image plane of an upright research-grade microscope (Zeiss Axioplan 2). The spectral resolution of both aperture coded spectrometers is about 1nm over the range of 550nm-665nm. The spatial resolution for both system designs differ. The first design is limited by the 10x Nikon objective used which yields a 5.4 micron spatial resolution. The second design is limited by the coupling optics and the various Zeiss objectives used yielding a spatial resolution range from 7.7 microns to 1.54 microns. We have proof-of-concept datacube results with a monochromatic and bichromatic illuminated chrome on quartz mask 'DISP'. Thus far, experimental results have been extended towards reconstructions made with fixed-cellular assays. A future goal invovles extending this technology to biologically relevant microscopy-based applications.
- (Peer Review) Gehm, M.E., Kim, M., Fernandez, C. , and Brady, D. "High-throughput, multiplexed pushbroom hyperspectral microscopy," Optics Express
- Gehm, M.E. and Brady, D.J., High-throughput hyperspectral microscopy, Proceedings of SPIE - The International Society for Optical Engineering, vol. 6090 (2006), pp. 609007-, San Jose, CA, United States [12.644828]
Multispectral aperture coded snapshot imaging microscope (MacSim)
MacSim is based on a dual disperser optical architecture which using compressive sensing signal processing techniques in order to measure a 3D data cube (2D spatial, 1D spectral) in a snapshot.
MacSim can measure over thirty spectral channels over the spectral range of 450nm-750nm. The spectral resolution of MacSim is about 10nm. The goal of MacSim is to produce a datacube in a single snapshot. Our application of interest includes imaging dynamic cellular events and fixed cellular assays for fluorescence microscopy applications.
- M.E. Gehm, R. John, D.J. Brady, R.M. Willet, and T.J. Schulz,, "Single-shot compressive espectral imaging with a dual-disperser architecture," Opt. Express 15, 14013-14027 (2007)