We present a straightforward approach to making sensitive fluorescence measurements using a chopped laser and phase-lock detection scheme. By using high-quality optical filters in the excitation and detection paths, the trade-off between spectral information and ultimate sensitivity is controlled by the choice of filter edge locations and bandwidths. Using this approach, we demonstrate a sensitivity of ~1 pW optical power of detected fluorescence over a bandwidth of ~125 nm centered at 505 nm using a 405 nm diode laser as an excitation source. We present the details of the measurement technique and discuss its value in selection of optical materials for fluorescence-based analytical systems.
The design study herein analyzes the design complexity of high zoom ratio lens systems in the visible, SWIR, and LWIR spectrums with four zoom groups (two internally moving). The aforementioned 12.5x zoom lens systems have been designed for use in the Coast Guard for maritime safety, security, and stewardship. To begin our comparative design study, the most advantageous solutions for distinct power groupings were found using a first order solution finder tool. The results showed that solutions with a PNNP, PNPP, and NPNP power grouping with the aperture stop in the third or fourth group had the most potential. At the end of the design process, a comparison was done for the three different wavebands to analyze the relative design complexity. Design complexity metrics were as follows: element count, number of aspheric surfaces, system total track length, element diameter, and tolerance sensitivity.
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