Abstract: An acoustic lens for use in an acoustic microscope including a solid state medium for propagating an acoustic wave having a wavelength .lambda. and having opposed end surfaces, an electric-acoustic transducer applied on one end surface of the solid state medium and having a radius a, and a spherical lens portion formed in the other end surface of the solid state medium and having an aperture of a radius w. The length l and the aperture radius w are normalized by the transducer radius a such that Z=l.lambda./a.sup.2 and W=w/a. Values of Z and W are selected from such a region in a first quadrant of the Z-W coordinate system that desired power and/or phase are obtained. The region neighboring the point Z=1 and W=1 is excluded.

Abstract: A coherent laser light flux is projected into a cell made of transparent quartz and light scattered from particles suspended in an antigen-antibody reaction liquid contained in the cell is detected by a photomultiplier by means of a collimator. An output electrical signal from the photomultiplier is sampled at different time instances and samplings are supplied to a fast Fourier transformer to derive a plurality of power spectrum desnities of fluctuation in intensity of the scattered light. A plurality of power spectrum densities are averaged to generate a mean power spectrum density. An amount of antigen contained in the reaction liquid is measured in accordance with the mean power spectrum density.

Abstract: A coherent laser light flux is projected into a cell made of transparent quartz and light scattered from particles suspended in an antigen-antibody reaction liquid contained in the cell is detected by a photomultiplier by means of a collimator. An output electrical signal from the photomultiplier is sampled at different time instances and samplings are supplied to a fast Fourier transformer to derive a plurality of power spectrum densities of fluctuation in intensity of the scattered light. A plurality of power spectrum densities are averaged to generate a mean power spectrum density. An amount of antigen contained in the reaction liquid is measured in accordance with the mean power spectrum density.

Abstract: A mechanism for attaching an ultrasonic head of an ultrasonic microscope to a vibration shaft of a vibrator is disclosed. A first connector half to which an R.F. cable is connected is fixedly arranged to the vibration shaft and a second connector half having the ultrasonic head coupled therewith is detachably attached to the first connector half, so that an exchange of the ultrasonic head can be performed in an easy and swift manner without affecting the position and characteristics of the R.F. cable.