Abstract: Embodiments of the present invention disclose a method, user equipment, base station, and system for detecting sharing of a timing advance value, relate to the field of communications technologies, and solve a problem in the prior art that a normal service cannot be provided because a TA value cannot be shared between different uplink CCs. According to the embodiments of the present invention, the user equipment may determine, through a time offset between synchronization of downlink component carriers corresponding to uplink component carriers, that a too large time offset indicates that a same TA value cannot be shared; the base station may calculate a TA value directly through a dedicated preamble sequence, and then compares the TA value with a TA value of one of the component carriers, where a too large difference between the TA values indicates that a same TA value cannot be shared.

Abstract: The invention is an apparatus and method for second harmonic optical coherence tomography of a sample comprising a laser coupled to an interferometer which has a reference arm and in a sample arm. A nonlinear crystal in the reference arm generates a second harmonic reference signal. The sample typically backscatters some second harmonic light into the sample arm. A broadband beam splitter optically coupled to the reference arm and sample arm combines the signals from the reference arm and sample arm into interference fringes and a dichroic beam splitter splits the interference fringes into a fundamental and second harmonic interference signal. A detector is optically coupled to the dichroic beam splitter detects interference fringes from which both an OCT and second harmonic OCT image can be constructed using a conventional data processor.

Abstract: The invention is an apparatus and method for second harmonic optical coherence tomography of a sample comprising a laser coupled to an interferometer which has a reference arm and in a sample arm. A nonlinear crystal in the reference arm generates a second harmonic reference signal. The sample typically backscatters some second harmonic light into the sample arm. A broadband beam splitter optically coupled to the reference arm and sample arm combines the signals from the reference arm and sample arm into interference fringes and a dichroic beam splitter splits the interference fringes into a fundamental and second harmonic interference signal. A detector is optically coupled to the dichroic beam splitter detects interference fringes from which both an OCT and second harmonic OCT image can be constructed using a conventional data processor.