A method for acquiring range data based on time-correlated single-photon counting is described. This method uses a short-pulse ( approximately 10-ps) laser diode, a detector based on a silicon single-photon avalanche diode, and standard photon-counting timing electronics. The accuracy of the technique has been measured as approximately +/-30 microm in a laboratory experiment and corresponds closely to the results of a theoretical simulation.

The design and implementation of a prototype time-of-flight optical ranging system based on the time-correlated single-photon-counting technique are described. The sensor is characterized in terms of its longitudinal and transverse spatial resolution, single-point measurement time, and long-term stability. The system has been operated at stand-off distances of 0.5-5 m, has a depth repeatability of <30 mum, and has a lateral spatial resolution of <500 mum.

The design and operation of a noncontact surface profilometry system based on the time-correlated single-photon-counting technique are described. This system has a robust optomechanical design and uses an eye-safe laser that makes it particularly suitable for operation in an uncontrolled industrial environment. The sensitivity of the photon-counting technique permits its use on a variety of target materials, and its mode of operation does not require the continual presence of an operator. The system described has been optimized for a 1-25-m standoff, has a distance repeatability of <30 microm, and has a transverse spatial resolution of approximately 60 microm at a 2-m standoff and approximately 400 microm at a 13-m standoff.

A commercially available germanium avalanche photodiode operating in the single-photon-counting mode has been used to perform time-resolved photoluminescence measurements on InGaAs/lnP multiple-quantum-well structures. Photoluminescence in the spectral region of 1.3-1.48 µm was detected with picosecond timing accuracy by use of the time-correlated single-photon counting technique. The carrier dynamics were monitored for excess photogenerated carrier densities in the range 10(18)-10(15) cm(-3). The recombination time is compared for similar InGaAs-based quantum-well structures grown by use of different epitaxial processes.

In this work the Preisach classical and nonlinear models are used to model the hysteretic response of a piezoceramic deformable mirror for use in adaptive optics. Experimental results show that both models predict the mirror behavior to within 5% root-mean-squared (rms) error. An inversion algorithm of the Preisach classical model for linearization of the mirror response was implemented and tested in an open-loop adaptive optics system using a Shack-Hartmann (SH) sensor. Measured errors were reduced from 20% rms to around 3%.

Time-resolved photoluminescence has been used to study carrier recombination in n- and p-type doped ZnSe at room temperature. A band-edge photoluminescence decay time of ∼240 ps has been measured for heavily doped n-type material together with a relaxation time of a few microseconds for the associated deep-level emission. The band-edge photoluminescence decay time for p-type doped material was ≤11 ps and is indicative of a high level of nonradiative Shockley–Read recombination.

The processing and analysis are described of range data in a time-of-flight imaging system based on time-correlated single photon counting. The system is capable of acquiring range data accurate to 1Opm at a standoff distance in the order of lm, although this can be varied substantially. It is shown how fitting of the pulsed histogram data by a combination of a symmetric key and polynomial functions can improve the accuracy and robustness of the depth data, in comparison with methods based on upsampling and centroid estimation. The imaging capability of the system is also demonstrated.

A novel, entirely solid-state, instrument has been developed for the study of time-resolved photoluminescence in a wide variety of bulk semiconductors, low-dimensional structures, and other materials. This system uses a frequency-doubled GaAlAs diode laser (pulse width 30 ps) as the 415-nm pump source and a silicon single-photon avalanche diode for detection of photoluminescence. The time-correlated single photon counting technique allows measurement of photoluminescence decays in the temporal region of 10 ps to ≳500 ns with high statistical accuracy. In addition, the combination of a microscope with a small-area detector provides a spatial resolution of &lt;5 μm. This system is currently being used for the measurement of picosecond time-resolved photoluminescence from II-VI semiconductors.