Abstract: A semiconductor laser drive apparatus having a semiconductor laser source (LD) for generating a laser light; a switching means (Q2) for supplying the semiconductor laser source (LD) with a first modulated signal (S2) for driving the semiconductor laser source (LD) on the basis of a second modulated signal (S1); a current source (6) for supplying the switching means (Q2) with a current for producing the first modulated signal (S2) in the switching means (Q2); and a bias adjust means (VR) for adjusting a bias direct-current to be added to the first modulated signal (S2).

Abstract: A focus detecting device for an eye fundus camera including a target having a target pattern comprised of a first slit and a second and third slits disposed in parallel with and at the opposite sides of the first slit. The second and third slits are symmetrical to each other with respect to the first slit. Deflecting prisms are provided to deflect the luminous flux through the first slit in one direction perpendicular to the longitudinal axis of the first slit and the luminous fluxes through the second and third slits in the opposite direction. The slit pattern is convenient for automatic focus adjustment.

Abstract: An ultrasonic flowmeter includes: a transmitting device for transmitting a continuous ultrasonic wave into a fluid to be measured; a receiving device spaced by a predetermined distance from the transmitting device, for receiving the ultrasonic wave propagating in the fluid; a phase difference detecting circuit for detecting the phase difference between the transmission signal of the transmitting device and the reception signal of the receiving device by converting the phase difference into a time interval enlarged by a frequency mixing means; and a processing circuit for outputting a signal representative of the flow rate of the fluid in response to the output of the phase difference detecting circuit, whereby the flow rate of the fluid is measured with high accuracy by utilizing the phase difference between the signals at the transmission point and the reception point.