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When using an optical level, the endpoint may be out of the effective range of the instrument. There may be obstructions or large changes of elevation between the endpoints. In these situations, extra setups are needed. Turning is a term used when referring to moving the level to take an elevation shot from a different location.
The Y level or wye level is the oldest and bulkiest of the older style optical instruments. A low-powered telescope is placed in a pair of clamp mounts, and the instrument then leveled using a spirit level, which is mounted parallel to the main telescope. The term dumpy level (also builder's level) endures despite the evolution in design. They ...
Looking through the optical plummet pick up two of the tripod legs and position the cross-hairs over the marker. Tread all three legs into the grass, bitumen, concrete. Look through the optical plummet and using the thumbscrews put the cross-hairs back over the marker. Adjust the level of the tribrach by slackening the tripod screws and sliding ...
The commonly used datum is mean sea level. [3] Dumpy level – optical instrument used to establish or check points in the same horizontal plane. It is used in surveying and building with a vertical staff to measure height differences and to transfer, measure and set heights. Also called a builder's level or leveling instrument.
Figure 2: Optical setup of a Twyman-Green interferometer with a CCD image sensor. The interference occurs for white light when the path lengths of the measurement beam and the reference beam are nearly matched. By scanning (changing) the measurement beam path length relative to the reference beam, a correlogram is generated at each pixel. The ...
An optical line termination (OLT), also called an optical line terminal, is a device which serves as the service provider endpoint of a passive optical network. It provides two main functions: to perform conversion between the electrical signals used by the service provider's equipment and the fiber optic signals used by the passive optical ...
An optical phased array (OPA) is the optical analog of a radio-wave phased array. [1] By dynamically controlling the optical properties of a surface on a microscopic scale, it is possible to steer the direction of light beams (in an OPA transmitter [ 2 ] ), or the view direction of sensors (in an OPA receiver [ 3 ] ), without any moving parts.
An optical attenuator, or fiber optic attenuator, is a device used to reduce the power level of an optical signal, either in free space or in an optical fiber. The basic types of optical attenuators are fixed, step-wise variable, and continuously variable.