We present the use of multiwavelength combination sources in a direct method for improved central fringe identification in a white-light interferometric system. The optimum wavelength combinations of such sources can be obtained by the use of the results of a simple analysis. We find that this multiwavelength technique can greatly reduce the minimum signal-to-noise ratio required by the systemwhen used to identify the central fringe, and thus it offers an increased signal resolution. As a result, it is suitable for high-precision measurement purposes as well as for applications in coherence multiplexed interferometric sensor systems.

This article discusses the use of low coherence interferometric techniques, employing the so-called ‘‘white light interferometer,’’ for axial eye length measurement. This system utilizes two Michelson interferometers, each of which locates one of the surfaces of the eye, the cornea and the retina, respectively, and thus a simultaneous determination of the two surface positions of the eye gives the value of eye length. The experimental results carried out on a simulated eye are presented, showing that the proposed system is simple, easy to align, suitable for measuring different kinds of eyes, tolerant to transverse eye movement, and worth further exploration.

Results of a study on the use of synthesized light sources in white-light interferometry are presented. The optimum wavelength combination with a pair of multimode laser diodes used to generate a synthetic wavelength source was simulated theoretically and verified experimentally. Using the best wavelength combination, we found that the lowest signal-to-noise ratio required by the system was 18.1 dB in theory and 22.1 dB from experiment. The relationships between the wavelengths of the two diodes used, their coherence lengths, and the signal-to-noise ratio required by the system are shown and discussed.

No abstract

No abstract