Two-dimensional imaging and three-dimensional reconstruction of low reflectivity surfaces by using the range-gating upconversion second-harmonic method.
Three-dimensional images of objects with very low reflectivity are obtained through a nonlinear upconversion gating with amplified femtosecond laser pulses. The current sensitivity of 10(-10) of the incident pulse intensity can be improved by use of better nonlinear crystals and higher-intensity gating pulses. The intensity rejection ratio between two coherent pulses with a delay of a few millimeters between them is better than 2 orders of magnitude. The depth resolution is ~15 µm. The transverse resolution of 300 µm is mainly limited by the two-dimensional detector that was used.
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Yan
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Diels