Coded cylindrical drums mounted on the pointers of dials of a meter are provided with parallel axially aligned rows of data elements constituted by opaque and transparent areas. Each of the drums is provided with a transparent centrally located ring parallel to the rows. Light is transmitted diametrally through the drums thereby intersecting the same at two places. So that the light will scan the rows as they are brought into position and so that the light can escape through the transparent ring, the light is converged at two spaced and orthogonally related lines for each drum. This is accomplished by passing the light through a positive aspherical or a spherical lens and cylindrical lens in series. The light is thereby converged at two orthogonally related lines respectively located at a shortened focal length due to the added power of the cylindrical lens and at the positive lens' normal focal length. The difference of the two focal lengths corresponds to the cylindrical drum diameter. A masking arrangement can be utilized to expose the data elements in sequence to reduce the photoelectric elements necessary for data pickup. The masking arrangement can provide synchronization pulses to identify the data elements. A transponder transmits the collected data to a remote central station.

A two-dimensional illuminating array comprising discretely addressable pixel portions (e.g. a light valve array) is imaged by lens means onto optical mapping means (e.g. a light diffracting or refracting array). The mapping means re-images the pixel portions of the illuminating array as a predetermined line pixel pattern at a linear pixel region.

A method and apparatus for holographically processing optical signals in a fiber-optic sensor system. In the present invention, holographic processors are utilized in various combinations with light sources, fiber-optic transmission means, sensors and detectors to provide low cost, compact, sensitive and accurate sensor systems. By means of the holographic processors of the present invention, the aforementioned sensor systems are used to monitor such physical parameters as temperature, pressure, flow-rate, and the like, and to provide output signal indications thereof that are compatible with digital receiving stations and immune to electro-magnetic interference, hazardous atmosphere, and the inimical effects of inadvertent intensity variation due to equipment vibration and the like. In one typical embodiment, a pair of holographic processors are employed in a color multiplex-demultiplex sensor system in which a first holographic processor is employed to color multiplex a sensor signal and a second holographic processor is employed to decode the color-multiplexed signal into a binary pattern that is then transmitted onto a set of photodetectors. In each of the embodiments of the invention disclosed, a unique geometrical orientation of a hologram is utilized to minimize spurious signal interference that would otherwise hamper or totally preclude the holographic processing.

A super high resolution rotary optical encoder having as its disk an optical disk, i.e., a disk employing the optical principle of non-contact readout based on diffraction theory. The encoder is adapted to be coupled to a device of which it is desired to measure the rotational motion thereof. The encoder includes an optical disk having, at a fixed radial distance, at least one track of pits and lands; a coupler for coupling the optical disk to the device such that rotary motion of the device results in a corresponding rotary motion of the optical disk; and an optical disk pick-up for generating an output in response to the pits and lands indicative of the rotary motion of the device.