  The power spectrum of an optical field can be acquired without a spectrally
resolving detector by means of Fourier-transform spectrometry, based on
measuring the temporal autocorrelation of the optical field. Analogously, we
here perform temporal envelope measurements of ultrashort optical pulses
without time resolved detection. We introduce the technique of Fourier
transform chronometry, where the temporal envelope is acquired by measuring the
frequency autocorrelation of the optical field in a linear interferometer. We
apply our technique, which is the time-frequency conjugate measurement to
Fourier-transform spectrometry, to experimentally measure the pulse envelope of
classical and single photon light pulses.
