AUGUST 1998 REPORT FOR

W. CHARLES SYMONS, III

In addition to teaching Circuits II, the past month was spent working with the new EOSI tunable laser diode and the NSOM computer. First, the EOSI laser, pictured in Figure 1, was put through a quick test just to verify that it was operational. For this test, the InSb camera was utilized to monitor the output as the wavelength was tuned from approximately 1725 nm to 1775 nm. In one case, a polystyrene sample was utilized while in a second case, only a background was recorded, i.e., no sample. In general, it appeared as if the laser tuned according to specifications. The diode power curves versus current and wavelength can be seen in Figures 2 and 3 below.

Figure 1: EOSI Tunable Laser Diode System.

Figure 2: EOSI Laser Diode Power Versus Current Curve.

Figure 3: EOSI Laser Diode Power Versus Wavelength Curve.

In addition to testing the new tunable diode laser, the NSOM control computer was tested with the National Instruments A-to-D and GPIB boards under Windows 3.1. While the A-to-D board functioned well, the GPIB board does not have drivers compatible with Win 3.1. Due to this difficulty, the GPIB interface for coarse control of the NSOM stage will either be worked around or a new Win 3.1 compatible board will have to be obtained.