The present application relates to a real-time measurement method and system for ultrafast space-time-frequency three-domain information based on space-time-frequency compression. The method includes: generating an ultrafast-pulse optical signal in a to-be-observed physical system; performing intensity-modulated spatial encoding on the ultrafast-pulse optical signal; arranging, by a space-time editor, a time-domain series of an encoded ultrafast-pulse optical signal in a horizontal space direction; performing, by a frequency-space editor, frequency spectral processing on a space-time distribution encoding form of the encoded ultrafast-pulse optical signal; performing, by a frequency-time delayer, frequency-time delaying on an encoded space-time-frequency synchronized ultrafast-pulse optical signal; performing, by an area array detector, real-time compression and acquisition on a high-frequency-resolution encoded space-time-frequency synchronized ultrafast-pulse optical signal, to obtain compressed encoded data information; and decompressing and decoding data according to the compressed encoded data information, to obtain space-time-frequency three-domain synchronization information of the ultrafast-pulse optical signal.

Ultra-short pulse detection. At least some example embodiments are methods including: receiving by an antenna a series of ultra-short pulses of electromagnetic energy at a repetition frequency, the receiving creates a pulse signal; self-mixing or intermodulating the pulse signal by applying the pulse signal to a non-linear electrical device, thereby creating a modulated signal; and filtering the modulated signal to recover a filtered signal having an intermodulated frequency being the repetition frequency.

The present invention relates to a apparatus and method for measuring a waveform of a light wave. A light wave measurement apparatus according to an embodiment of the present invention includes a pulse separation unit to separate an input light wave into a fundamental pulse and a signal pulse, a time delay adjustment unit to adjust a time delay between the fundamental pulse and the signal pulse, a focusing unit to focus the fundamental pulse and the signal pulse whose time delay is adjusted on an ionization material, and an ionization yield measurement unit to measure an ionization yield from electrons and/or ions generated by the focused fundamental pulse and signal pulse. The waveform of the input light wave is obtained by obtaining an ionization yield modulation changed by the signal pulse as a function of the time delay.

A method for measuring the delay between N pulses having a duration less than 100 picoseconds comprises the steps: collimated emission of the pulses having the same repetition frequency, emission of a reference pulse having the same repetition frequency capable of producing interference fringes with each of the pulses, for each of the pulses, detection, by a detector, of the coherent sum of this pulse with the reference pulse, this sum producing the interference fringes, the fringes originating from each of the pulses being distinguishable from one another. The reference pulse is emitted with an adjustable delay, and the method further comprises: for each delay, simultaneous measurement for the pulses of N contrasts of the interference fringes, for each of the pulses, a delay value between this pulse and the reference pulse is determined by the delay corresponding to the maximum contrast.

Ultra-short pulse detection. At least some example embodiments are methods including: receiving by an antenna a series of ultra-short pulses of electromagnetic energy at a repetition frequency, the receiving creates a pulse signal; self-mixing or intermodulating the pulse signal by applying the pulse signal to a non-linear electrical device, thereby creating a modulated signal; and filtering the modulated signal to recover a filtered signal having an intermodulated frequency being the repetition frequency.

A method for measuring the delay between N pulses having a duration less than 100 picoseconds comprises the steps: collimated emission of the pulses having the same repetition frequency, emission of a reference pulse having the same repetition frequency capable of producing interference fringes with each of the pulses, for each of the pulses, detection, by a detector, of the coherent sum of this pulse with the reference pulse, this sum producing the interference fringes, the fringes originating from each of the pulses being distinguishable from one another. The reference pulse is emitted with an adjustable delay, and the method further comprises: for each delay, simultaneous measurement for the pulses of N contrasts of the interference fringes, for each of the pulses, a delay value between this pulse and the reference pulse is determined by the delay corresponding to the maximum contrast.

The present invention relates to a apparatus and method for measuring a waveform of a light wave. A light wave measurement apparatus according to an embodiment of the present invention includes a pulse separation unit to separate an input light wave into a fundamental pulse and a signal pulse, a time delay adjustment unit to adjust a time delay between the fundamental pulse and the signal pulse, a focusing unit to focus the fundamental pulse and the signal pulse whose time delay is adjusted on an ionization material, and an ionization yield measurement unit to measure an ionization yield from electrons and/or ions generated by the focused fundamental pulse and signal pulse. The waveform of the input light wave is obtained by obtaining an ionization yield modulation changed by the signal pulse as a function of the time delay.

The present application relates to a real-time measurement method and system for ultrafast space-time-frequency three-domain information based on space-time-frequency compression. The method includes: generating an ultrafast-pulse optical signal in a to-be-observed physical system; performing intensity-modulated spatial encoding on the ultrafast-pulse optical signal; arranging, by a space-time editor, a time-domain series of an encoded ultrafast-pulse optical signal in a horizontal space direction; performing, by a frequency-space editor, frequency spectral processing on a space-time distribution encoding form of the encoded ultrafast-pulse optical signal; performing, by a frequency-time delayer, frequency-time delaying on an encoded space-time-frequency synchronized ultrafast-pulse optical signal; performing, by an area array detector, real-time compression and acquisition on a high-frequency-resolution encoded space-time-frequency synchronized ultrafast-pulse optical signal, to obtain compressed encoded data information; and decompressing and decoding data according to the compressed encoded data information, to obtain space-time-frequency three-domain synchronization information of the ultrafast-pulse optical signal.

A method of determining a location of an optical fibre positioned at least partially inside a scattering medium, the method comprises transmitting pulsed light into the scattering medium, receiving, by a detector, photons of the pulsed light that have passed through the scattering medium, selecting signals corresponding to some of the received photons, wherein the selecting is based on a time of arrival of the received photons; and determining a location of the optical fibre based on the selected signals.