Abstract: A thermally shock resistant ceramic body, such as a porous ceramic honeycomb structure for a wall flow diesel engine exhaust filter or a flow-through ceramic catalyst support, is formed of a composite ceramic material comprising a major first ceramic phase exhibiting good thermal shock resistance and a minor second phase material that substantially reduces the elastic modulus of the composite ceramic material at elevated temperatures.

Abstract: A modulation spectroscopy system (1) directs a probe beam (11) onto a sample (10), the reflected probe beam being collected by a collector (7) and processed by a detector (8). A pump beam generated by a source (4, 5) directs a pump beam (13) onto the sample at the same spot as the probe beam. However, it also switches the pump beam via a path (14) onto an adjacent location not overlapping the probe spot. This is referred to as spatial modulation. A cylindrical lens (16) in the collection subsystem (7) collects reflected light including luminescence from both pump beam spots simultaneously, so that the luminescence becomes a d.c. signal which can be easily eliminated, including means from the modulator for varying pump beam intensities and positions. This provides means to reject the unwanted background luminescence signal as well as improvement to the signal to noise ratio.

Abstract: A modulation spectroscopy system (1) has an acousto-optic modulator (5) providing a pump beam onto a sample. The modulator receives a light beam from a source (4) and diffracts it to provide an output which is the first order beam, the zeroth order or undeflected beam being terminated and the 2nd and higher orders being negligible and terminated also. The modulator is driven alternately by two drive frequencies at a modulation or toggle frequency. The first order output is at one angle for a first drive frequency and at another angle for the other drive frequency. The duty cycle of alternating between the different drive frequencies sets the output beam position duty cycle for incidence at two different spots on the sample. Also, either or both beams may be position and/or intensity varied by control of the modulator drive frequencies and their amplitudes.