Background Serum feline pancreatic lipase immunoreactivity (fPL) commonly is used in the assessment of sick cats suspected to have pancreatitis but its diagnostic utility is debated. Objectives To evaluate the diagnostic utility of the Spec fPL test and selected serum biochemistry tests in the diagnosis of pancreatitis in cats. Animals Two hundred seventy‐four client‐owned cats presented to a university teaching hospital in the United Kingdom, from April 2013 to May 2017, in which Spec fPL was measured. Methods Cats were classified into 1 of 4 groups based on clinical signs (all cats), ultrasonographic findings (all cats) and histopathological or cytological assessment of the pancreas where available (9 cats) regardless of Spec fPL concentration. The groups were (a) definite pancreatitis (n = 9), (b) probable pancreatitis (n = 49), (c) possible pancreatitis (n = 139), and (d) unlikely pancreatitis (n = 77). Spec fPL and selected serum biochemistry test results were compared among groups. Results Serum fPL concentrations >5.3 μg/L were classified as positive and concentrations <3.5 μg/L were classified as negative. There was a significantly ( P = .03) lower proportion of false‐positive results (cats unlikely to have pancreatitis, n = 77, with a positive fPL, n = 8, 10%) than false‐negative results (cats with definite or probable pancreatitis, n = 58, with a negative fPL result, n = 14, 24%). None of the selected biochemical tests were helpful diagnostically. Conclusion and Clinical Importance A positive Spec fPL result indicates that pancreatitis is a probable diagnosis, but the test cannot be used to rule the diagnosis out.

Rapid manufacturing of high purity fused silica glass micro-optics using a filament-based glass 3D printer has been demonstrated. A multilayer 5 × 5 microlens array was printed and subsequently characterized, showing fully dense lenses with uniform focal lengths and good imaging performance. A surface roughness on the order of R a = 0.12 nm was achieved. Printing time for each lens was <10 s. Creating arrays with multifocal imaging capabilities was possible by individually varying the number of printed layers and radius for each lens, effectively changing the lens height and curvature. Glass 3D printing is shown in this study to be a versatile approach for fabricating silica micro-optics suitable for rapid prototyping or manufacturing.

A stable, narrow-bandwidth (274 MHz) backward wave optical parametric oscillator (BWOPO) generating mJ-level backward signal at 1885nm and forward idler at 2495 nm is presented. The BWOPO was pumped by a single-longitudinal mode, Q-switched Nd:YAG high-energy laser at 1064 nm. We show that multi-transversal mode pumping leads to the spectral broadening of the BWOPO backward signal and the generation of nanosecond pulses 2.7 times above the Fourier transform limit. We demonstrate over 100 GHz continuous tuning of the parametric output by adjusting the temperature of the BWOPO crystal, showcasing the significant role of thermal expansion in tuning performance. The BWOPO signal was used as a seed for a single-stage PPRKTP optical parametric amplifier (OPA) to boost the narrowband signal and idler energies to 20 mJ. This combination of mJ-level BWOPO seed with a single-stage PPRKTP OPA comprises a simple concept that would benefit long-range differential absorption lidar (DIAL) in the near and mid-infrared regions.

We demonstrate periodic poling of large aperture Rb-doped KTP (RKTP) crystals with a QPM period of 3.43 µm via coercive field engineering. The periodically-poled RKTP has excellent pattern-fidelity, with a second harmonic generation (SHG) conversion efficiency of 1.4%/Wcm at 405 nm. We use ion-exchange (IE) to fabricate grating of high-and-low coercive fields and establish that the depth of the in-diffused Rb+ is the main parameter to achieve sufficiently large coercive field contrast that enables uniform periodic poling in the thick crystal. Furthermore, we demonstrate that our robust coercive field grating allows multiple cycles of polarization-switching which can be employed to decrease the refractive-index change along the polar axis, induced during the IE process.

Large aperture periodically-poled Rb:KTP crystals designed for optical parametric amplifiers in 2 µm LIDAR systems were radiation hardness tested by exposure of proton beams at 10 MeV and 60 MeV energies. An irradiation dose of 55 Gy was used to commensurate the crystals’ estimated exposure on board a mission in the low-Earth orbit. The irradiation effects were investigated by comparing optical transmission spectra and 2D effective nonlinearity mapping in a 2 µm OPO setup before and after irradiation. The results reveal that the periodically poled structure remained intact after irradiation, and the changes in the optical transmission and nonlinear properties were close to the measurement uncertainty. This investigation is essential for realizing efficient frequency converters for space applications, such as spaceborne active greenhouse gas monitoring LIDAR instruments or correlated photon-pair sources.