Figure 1: NSOM Software Interface Window During a Test Run.
During the past month, the majority of time was spent developing and implementing the near-IR NSOM's LabView code. The interface for the instrument can be seen in Figure 1 below. In general, the NSOM instrument code collects both a signal and background reading for the modulated 650 Hz laser signal. The 650 Hz signal is separated from other noise components including strong 60 Hz and DC signals via a digital bandpass filter while the strength of the signal is determined via a FFT routine. The Log of the ratio is then calculated to produce an absorbance value for the image point. The code then instructs the instrument to scan to the next image point and repeat the data collection procedure. This process is continued until a complete absorbance image is obtained. The NSOM image is graphed within the image window of the software while the data collection can be monitored point by point within the linear data graph of the software as depicted in Figure 1. Once an image is collected at a single near-IR wavelength, the software then collects additional images at multiple wavelengths. To this end, the software either allows the user to adjust the wavelength for coarse wavelength scans or it adjusts the piezo voltage for fine wavelength scans.
In addition to the NSOM instrument software, a parallel code was written utilizing the same base routines to collect near-IR spectral data for the lab's near-IR catheter project. Both signal and background voltages are collected from the catheter utilizing the same 650 Hz modulated laser signal. In this manner, the same DSP routines utilized in the NSOM code can be reused for the catheter project. At this point, preliminary tests indicate that both software interfaces are functioning as expected.
During the development of the NSOM and catheter codes, a final abstract for the 1999 Pittsburgh Conference was submitted. This abstract entitled NEAR-IR SPECTRAL IMAGING BEYOND THE DIFFRACTION LIMIT can be viewed online. Furthermore, a progress report for my IGERT fellowship was also submitted. While the progress report due date was postponed until later this month, the current version can be viewed online but may change due to the addition of new material.