By the development of electronic computer, the use of spot diagram for evaluation of optical image has become practical, but the computation involves the time-consuming and troublesome skew ray tracing, for which simplification, Herzberger's interpolation method is applied and the transfer function is obtained by using a lens of F/2.5, f=75 mm as R(s, t)=1/N_??_ exp[-2πi(sΔxi+tΔyi)] With this transfer function, the interpolation method is compared with the exact skew ray tracing method in regard to the accuracy. The relation found between the number of sampling points that were used to determine the coefficients of the interpolation formula and the accuracy of the coefficients or the transfer function shows that the skew ray tracing of 7 sampling points for 0° incident angle and 12 sampling points for 15° incident angle are sufficient for the accuracy. Good results are obtained on lenses of F/4 and lower apertures but not on lenses of higher apertures such as F/2.5.
For repetition of discharge of a condenser bank in a high current circuit, the operation of air gap for the control of high current is automatized in consideration of instability of air gap that causes the discharge voltage to fluctuate. If the air gap starts its action when the voltage is low, the automatic mechanism stops the charging of condenser at once and sets the charging relay back to its initial condition. If, despite high voltage, the air gap fails to act, triggering pulses are applied at given intervals until the action starts. If the surface flush-over originates on condenser leads or other components of high current circuits, the charging is stopped by a relay. All the relay circuits are so devised that the operation can be either automatic or manual. The action of every component of the circuit is discussed.
Pyroelectric current induced by irradiation of modulated microwave of 9300 Mc/s frequency is observed on a single crystal of BaTiO3 mounted in a wave guide. The resultant pyro-electric current density is given by _??_ The numerical value of the rate dPs/dT of the crystal is about 1×10-8 coulomb/cm2/°C at room temperature, and when heated uniformly in a microwave electric field, the rate of temperature rise is given by _??_ where B is a constant relating to the heat flow from the crystal, α a constant, mainly determina-ble by physical properties of the crystal, and W(t) the incident microwave power as a function of time. As for the characteristics of pyro-current, slowly varying current that is induced by sinusoidally modulated power of very low frequency is measured with an electrometer provided with a pen recor-der, and quickly varying current that is found at the time when incident power is modulated or switched on is observed with a synchroscope combined with a pre-amplifier. The characteristics observed at low power levels conform to those expected of the temperature changes in the crystal estimated with a few functional forms of W(t). However, when the incident microwave power reaches a certain value in the range of several hundred milliwatts, the pyro-electric effect disappears suddenly with simultaneous generation of noise, the cause of which is the disordered domain structure in the crystal.
A β-ray spectrometer suitable for low level samples has been constructed. In order to reduce the background counting rate, sum signals of output pulses from an “analyzing” and a “window” scintillator are analyzed in coincidence with signals from the window scintillator. These two scintillators are mounted on one photomultiplier tube, and the window signals are selected by means of pulse shape discrimination with double delay line clipping. A CsI (Tl) crystal (2"φ×3.5 mm) is used as the analyzing scintillator and a plastic scintillator (1"φ×0.5, ×1.25 or×1.9 mm) as the window. When a window scintillator of 1.9 mm in thickness was used, the background was by a factor of about 70 in a lead shield of 10 cm in thickness, and its counting rate was about 1.0 cpm for the energy range from 0.15 to 1.7 MeV. The limit of the pulse shape discrimination is discussed concerning the relations among signal fluctuation, discrimination energy and thickness of the window scintillator.