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A CMOS pixel with local processing suitable for use in a modulated light camera is described. The pixel was designed to detect sinusoidally modulated light within the frequency range of 500 kHz–25 MHz. It consists of a photodiode, a transimpedance amplifier, a mixer and an active 150 Hz bandpass filter. It is a prototype design capable of further size reduction suitable for tiling into an array for imaging purposes. This allows the modulated light component of a frequency far in excess of the frame rate to be detected at the pixel level.

The amplitude and phase distributions at the back focal plane of a scanning interferometer are used to determine the phase of the optical reflection coefficient. This value for phase change is then used to correct the overall phase measured with the interferometer, so that pure topography measurement is achieved.

The use of computer generated holographic zoneplates to enhance the generation of laser ultrasound is described. An amplitude grating capable of focusing laser light onto an arc which in turn generates a near diffraction limited focus of 82 MHz Rayleigh surface waves is also described. The application of zoneplates for ultrasonic nondestructive evaluation and imaging is considered.

A scalable 4×4 array of photodiodes and circuitry has been fabricated and used to make spatially resolved measurements of surface wave enhanced modulated thermoreflectance. In-phase and quadrature components of the modulated light at every pixel are measured in parallel, even in the presence of a large DC background.

A new photoreflectance (PR) system which uses only a single optical beam is described. The PR signal is detected at the second harmonic of the modulation frequency, contained in the backreflected light. To reliably measure this small signal, the second harmonic content of the incident beam is reduced by feedback to the modulator.

Efficient production of surface acoustic waves using optical distributions controlled by spatial light modulators is demonstrated. The measurements presented used only 40 mW average optical power on the sample surface. It is shown that a spatial light modulator produces light distributions which control the surface acoustic wave generation on the sample surface; this can be used to produce similar light distributions to those formed by computer generated holography.

An all-optical version of a scanning acoustic microscope is described. The electronic data acquisition system is a major advance on that previously reported, in that it is now capable of high speed acquisition of phase as well as amplitude images at 82 and 164 MHz.

Subsurface imaging in a non-contacting surface acoustic wave microscope is demonstrated, using mode conversion from Rayleigh to Lamb modes. The fact that, unlike in a conventional acoustic microscope, the technique does not require fluid couplants allows new contrast mechanisms to be used for the quantification of defects.

It has recently been reported that photoexcited carriers contribute to the contrast mechanism for thermal imaging of semiconductors. The letter demonstrates the applications and significance of this effect for imaging semiconductors with photothermal radiometry (PTR). The method leads to a direct way of monitoring the dynamics of the carrier plasma. The theoretical results are used to interpret the experimental results obtained from several semiconductor materials.

A new method of design of mm-wave Gunn oscillators has been developed and tested. The method utilises the fact that high frequency GaAs Gunn diodes work in the harmonic mode for transmission whilst allowing tuning at the fundamental. Hardware for wide frequency coverage (30 GHz centred at about 85 GHz) is described with experimental results.

Two new methods of providing equivalent Doppler frequency shift of reflected microwave signals have been developed. One is a mechanical spiral ‘barber's pole’ type of device. The other produces a single upper or lower sideband by purely electronic modulation techniques.

A new kind of hornodyne transmitter/receiver ‘Doppler radar’ device has been developed in which the Doppler beat envelope is pulse-sampled by the self-mixing action in a pulsed transferred electron diode. The advantages of such a system are discussed and the techniques for extracting the signal are described.

A mathematical theory is presented which shows that a moving reflector of waves gives rise to harmonics of the Doppler shift in the input impedance of the transmission medium. The analysis can be used to explain new ‘direction of motion’ detection phenomena.

We report the use of photothermal radiometric microscopy to image through silicon wafers. Experimental results are presented which show that the signal obtained decreases as the normal emissivity of the material on the back surface increases. The theory for the emissivity of partially transparent objects has been extended to explain these findings. We conclude that the contrast is due to photon-induced switching of the infra-red transmission coefficient of the silicon.

The letter describes how the scanning acoustic microscope may be operated in a continuous wave mode. By oscillating the sample by approximately a few hundred angstroms, single frequency amplitude and phase measurements may be obtained with the acoustic microscope. We also show that the method should allow very high frequency quantitative operation of the microscope, where conventional pulse echo methods would fail. A system implementation and preliminary results are presented.

The application of frequency-modulated continuous waves (FMCW) to the scanning acoustic microscope (SAM) is described. The technique provides a convenient way of separating specimen topography from reflectivity while enjoying the advantages of pulse compression. Furthermore, the system will enable sophisticated signal processing to be carried out at audio frequencies.

A new phenomenon has been observed with self-oscillating mixers which permits discrimination between approaching and receding homodyne radar targets. The detected Doppler low frequency signal shows nonsinusoidal asymmetry which allows signal processing circuitry to give gated display outputs for positive or negative Doppler shift of the microwaves. The phenomenon has been observed with GaAs and InP Gunn devices, and with silicon Impatt devices, thus demonstrating its general nature. The effect has been shown with both c.w.1.2 and pulsed3 self-oscillating mixers, and confirmed at 15, 33, 66 and 75 GHz.