Development of Axial Resolution Testing Device for Optical Coherence Tomograph for the Posterior Segment of the Human Eye and Measurement Uncertainty Analysis / 中国医疗器械杂志

Based on the analysis of the theoretical calculation model of axial resolution of optical coherence tomograph for the posterior segment of the human eye, a set of testing device for measuring its axial resolution is designed and developed. In view of a commercial ophthalmic optical coherence tomograph in clinical use, its axial resolution is calculated to be 5.07 μm theoretically, and the actual measurement value is 5.45 μm. The uncertainty of the detection device is evaluated and the result is (5.45±0.10) μm. The measurement error introduced by the testing device is very small. Meanwhile, the axial resolution measured by the testing device meets the requirements of the instrument(≤ 6 μm).

A Simplifed Model Eye for Testing Fundus Imaging Device / 中国医疗器械杂志

Based on the Gullstrand I model eye, a simplified model eye for testing fundus imaging device is designed. The model eye can reach the following requirements:(1) The refractive characteristics of the ocular refractive tissue are simulated, and the equivalent focal length in air is 17 mm; (2) The differences between relative refractive index differences of the adjacent materials of the simplified model eye and relative refractive index differences of any adjacent two layers (cornea and aqueous humor, aqueous humor and lens, lens and vitreous body) of the Gullstrand I model eye are not more than 1%; (3) In the case of the incident aperture diameter of 3 mm, the differences of radii of the diffuse spots formed by the paraxial light and the axial light are not more than 15%; (4) The differences of angles of chief ray and tangent line of the fundus are not more than 1°; (5) In the case of the incident aperture diameter of 3 mm, the differences of MTF values of the near axis light are not more than 0.1. The simplified model eye can be expected to be used for testing fundus imaging device instead of the test method in ISO 10940:2009 Ophthalmic instruments-Fundus cameras.

Study on the Photoelectric Performance Indicators of Medical Electronic Endoscope / 中国医疗器械杂志

OBJECTIVE@#To establish a method for measuring the photoelectric performance index (luminance response characteristic and luminance tolerance) of medical electronic endoscope.@*METHODS@#Based on the clinical application and product features of medical electronic endoscope, the umbrella grayscale test chart and the adjustable gray scale test chart are designed and made from two aspects of distribution and density differential.@*RESULTS@#The influence of gray scale arrangement, background illumination intensity and illumination spectrum on photoelectric performance measurement of electronic endoscope is verified by test.@*CONCLUSIONS@#It is a reference for the design analysis, evaluation and modification of electronic endoscope product photoelectric part, whether it is suitable for fast detection of umbels and more accurate gray scale test chart.

Method to Calculate the Yield Load of Bone Plate in Four-point Bending Test / 中国医疗器械杂志

This paper developed a calculation method to acquire the yield load P of bone plate during four-point bending test. This method is based on the displacement--force (δ-F) curve function f(M)(δ) obtained from the test, each slope of the curve was calculated using piecewise smooth function and the line segment in f(M)(δ) elastic deformation area was searched by setting the minimum slope T. Slope S was obtained through linear fit so as to build parallel displacement function f(L)(δ). Then, approximating intersection point of f(M)(δ) and f(L)(δ) was obtained through linear interpolation. Thus, yield load P was acquired. The method in the paper was loyal to YY/T 0342-2002 regulation and was liable to program calculation. The calculating process was nothing to do with whether the initial point during the test was preloaded or unloaded, and there was no need to correct the original point. In addition, T was set in an ideal fitting level guaranteed by the fitting coefficient of determination R2, and thus S was very close to the real value, and P was with a high accuracy.

Feasibility Research of Determined Oxygen Permeability of Finished Soft Contact Lens / 中国医疗器械杂志

<p><b>OBJECTIVE</b>A method for determined oxygen permeability (Dk) of finished soft contact lens.</p><p><b>METHODS</b>Oxygen permeability(Dk) of 10 group finished soft contact lens was determined by polarographic method, and the values were linearly calibrated using the measured and established Dk values of the specified reference materials.</p><p><b>RESULTS</b>Only one Dk value fell outside of the requirement of GB 11417.3-2012 tolerance for Dk (± 20%).</p><p><b>CONCLUSION</b>It is great practicability when determined the oxygen permeability (Dk) of finished soft contact lens by polarographic method which were linearly calibrated using the measured and established Dk values of the specified equal thickness reference materials without the measured lens customized 4 different thickness.</p>