A pressure vessel is provided for use in an undersea environment. The invention relates, in particular, to the determination of the sizes of particles in a particle stream. Trenches that define the boundaries of the individual devices are then formed through the semiconductor layers and into the insulating substrate, beneficially by using inductive coupled plasma reactive ion etching. The OAE is inserted into the beam path and adjusted. The catch and the cutter blade may not be operated relative to the base when the pole of the latch device is engaged in the orifice of the base, to prevent the cutter blade from being operated relative to the base by children inadvertently. The control circuit can control the color changing of the light emitting diode based on a reference signal from the synchronous pin.