In this paper we consider the problem of determining the most optimal parameters of an apparatus for measuring the thickness of the cornea in an interferometric method. Earlier, a formula was derived to determine the thickness of the corneal layer, taking into account the radius of curvature in the range from 0.5 mm to 1 mm and an error of 0.5-1.0%. The accuracy of the method depends on the quality of the determination of the thickness of the interference fringes. We consider the possibility of using this method for measuring tissue thicknesses over a wider range of values. The optimum values for the angle of incidence of the radiation we was selected by the experimental and calculation methods: 0.07 radians for the range from 0.01 mm to 0.1 mm and 0.17 radians for the range from 0.1 mm to 1 mm. We give a scheme of a simplified construction of an interference thickness meter and experimental interferograms with computer processing.
In this article we consider the problem of choosing the optimal parameter settings for measuring corneal thickness in the modified laser triangulation method. The accuracy of the method depends on the resolution of the light marks. For better resolution in this study we've chosen angles of viewing of the laser radiation (0.88 radians) and the position of the photodetector (0.17 radians). We calculated the maximum permissible laser power (0.1 mW), for which the tissue under investigation is not damaged yet: there is no ablation, scar formation and a change in the refractive index.
The results of studies on the effect of temperature on the output spectral characteristics of continuous semiconductor lasers of the visible range are presented. The paper presents the results of studying the spectral-optical radiation parameters of semiconductor lasers, their coherence lengths, and the dependence of the position of the spectral peak of the wavelength on temperature. This is necessary for the selection of the most optimal laser in order to use it for medical ophthalmologic diagnosis. The experiment was carried out using semiconductor laser modules based on a laser diode. The spectra were recorded by using a two-channel automated spectral complex based on the MDR-23 monochromator. Spectral dependences on the temperature of semiconductor lasers are obtained, in the range from 300 to 370 K. The possibility of determining the internal damage to the stabilization of laser modules without opening the case is shown, but only with the use of their spectral characteristics. The obtained data allow taking into account temperature characteristics and further optimization of parameters of such lasers when used in medical practice, in particular, in ophthalmologic diagnostics.
The problem of determining the thickness of thin films by the method of laser triangulation is considered. An expression is derived for the film thickness and the distance between the focused beams on the photo detector. The possibility of applying the chosen method for measuring thickness is in the range [0.1; 1] mm. We could resolve 2 individual light marks for a minimum film thickness of 0.23 mm. We resolved with the help of computer processing of photos with a resolution of 0.10 mm. The obtained results can be used in ophthalmology for express diagnostics during surgical operations on the corneal layer.
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