Non-contact picosecond electro-optic sampling with a semiconductor laser is proposed and experimentally studied focusing on the practical application in the field of IC testing. Adoption of a laser diode pulse generator being compact, inexpensive, highly reliable and easy to electrically control makes possible the measurement without chopping of the electrical signals under test, and the measurement where strobe laser pulses are electrically synchronized to the clock signal.
A newly developed longitudinal E-O sampling probe having a transparent back-side electrode enables one to measure voltages independently on the shape and the direction of electrodes under test, and to exactly monitor the measuring point on the electrode. It also makes possible the absolute voltage measurement.
Reduction of noise of the optical receiver and the strobe pulses is experimentally investigated. In addition, the space dependent sensitivity is studied and greatly improved by adopting a new method.
The equivalent input noise of 75 mV/√Hz with a temporal resolution of 32 ps at the space of 20μm between the probe tip and the device under test has been demonstrated.

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Random signals are utilized in many situation such as test signals for identification of a control system and the excitation sources of a material fatigue machine. In these cases, random signals with specified amplitude probability distribution are required. The generation of such random signals can be realized, to some extent, by filtering a single binary random signal. However, the distribution obtained by this method does not coincide with a specified distribution in high order moments.
This paper proposes an improved method which can generate a specified random signal by using many binary random signal sources. This method generates a random sequence x(j) by adding n binary random signal sequences r₁(j), r₂(j), …, r_n(j) (r_i(j)=0 or 1) with a weighted adder. In order to investigate the probability distribution, its characteristic function is expressed by the weights w₁, w₂, …, w_n of a weighted adder and the probability p₁, p₂, …, pn, where pi is the probability of 1 of the i-th binary random sequense. An algorithm of the determination of pi, wi(i=1, 2, …, n) for obtaining any specified distribution is described. An experiment shows that the proposed method can obtain better approximated probability distribution in comarison with the conventional method.

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The veiling-glare of infrared optical system as a figure of assessment is discussed. The veilingglare of germanium lenses, which have different surface roughness, were measured using the method proposed by author. Although the MTF's of the lenses obtained as Fourier transforms of line image distributions have no significant difference, the veiling-glare apparently vary in accordance with the surface roughness of lenses. The agreement of the veiling-glare with the contrast of images obtained through the lenses was very good, showing the usefulness of the veiling-glare for the assessment of infrared optical system.

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When considering the state-space model for a linear system with uncertain parameters, we often have a polytope of matrices as possible system matrices. Stability condition of a matrix polytope, however, has not been fully developed and useful stability criteria are few. With a view to shedding light on this stability problem, this paper considers the degree of stability, a quantitative measure of stability, for a polytope of matrices.
A lower bound of the degree of stability based on algebraic Lyapunov equations is proposed. It uses m positive definite symmetric matrices and aims at finding the best one that attains the maximum of the lower bound in the convex hull of the m matrices. The solution is expressed in terms of a zero-sum game, hence it can be solved easily by linear programming. The present approach makes it possible to improve the lower bound by increasing m. In this connection, condition is provided which guarantees a real improvement of the lower bound.
Stability of a matrix polytope can be tested by the proposed lower bound. Moreover we can obtain a Lyapunov function common to all the members of the matrix polytope, in case the polytope is determined to be stable. This common Lyapunov function is utilized for studying the stability of a large-scale system with unknown parameters.

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