Abstract: An imaging apparatus is provided with a negative lens, a variable focussing lens unit including a material with an electrooptic effect, a light blocking unit, including the material with the electrooptic effect, capable of changing an aperture diameter, and a switch, interlocked with each other, capable of supplying electric power to the variable focussing lens unit and the light blocking unit which are arranged in order on an optical axis from an object side to an image side. When the switch is turned off, the variable focussing lens unit is set to bring an object at a far point into focus and the light blocking unit is set so that an aperture is determined by an aperture stop, while on the other hand, when the swtich is turned on, the variable focussing lens unit is set so that an object at a near point is in focus and the light blocking unit is set to be smaller in aperture.

Abstract: An objective optical system is provided with at least one liquid crystal lens whose polarizing characteristic selected in a direction such that polarizing components of light reflected from the lens are counterbalanced and a variable liquid crystal stop is arranged at an angle with respect to an optical axis so that an incident direction of light is deviated to the side on which contrast between transmission and blocked states of light is maximized. The objective optical system enables the balance of the polarizing components to bring about a proper image for observation, can moderate asymmetry, relative to the optical axis, of the contract between the transmission and blocked states of light of the liquid crystal stop, and can secure an adjustable object image.

Abstract: A sensor comprises a tiny cantilever of a thin film having a detection region at its free end portion, a detector for detecting a displacement of the cantilever caused by material acting on the detecting region, and calculation unit for calculating an amount of the material acting on the detection region, based on the displacement of the cantilever which has been detected by the detector, thereby to measure the intensity of a particle-stream applied to the detection region or the thickness of a film formed on the detection region.

Abstract: At least a part of an image forming optical system is formed of a liquid crystal assembly consisting of a plurality of liquid crystals having a refractive index anisotropy and having different response frequencies of molecule orientation so that the transmittivity and refractive index of the plurality of liquid crystals may be independently controlled with few signal lines by varying the frequency of the driving signal applied to the liquid crystal assembly.

Abstract: A scanning tunnel microscope includes a piezo-actuator movable in a direction Z perpendicular to the surface of a sample and provided with a scanning probe projected downward from the bottom thereof. The scanning probe is moved in the direction Z by the piezo-actuator. The piezo-actuator includes a position measuring probe projected therefrom, parallel to the surface of the sample, from the lower end of one side thereof. A reference sample having concaves formed on a surface thereof at predetermined intervals is fixed to the piezo-actuator. When the scanning probe is moved in the direction Z, the position measuring probe is moved along the reference sample, so that tunnel current having a waveform which reproduces the shape of the concaved surface of the reference sample is detected. Thus, the moving distance of the scanning probe can be obtained from the waveform of tunnel current detected.

Abstract: A liquid crystal lens includes a liquid crystal cell formed by lens component members, at least one of the lens component members being formed of a Fresnel lens whose surface is formed by a number of annular ring-shaped Fresnel grooves with their crests leveled.