Prisms

We have the best surveying prisms for sale. We carry Surveying Prisms, Surveying Targets, Land Surveyors Peanut Prisms, Right-Angle Penta Prisms, Robotics Prisms, Total Station Prisms, and Surveyors Mini Prisms. Look for Surveying Prisms that are compatible with Surveying Instruments made by Leica Geosystems, Nikon, Northwest Instrument, Topcon, Apache, Crain, CST/berger, and Sokkia.

If you're looking for a Surveyors Prism Buying Guide, we can recommend that when selecting a Surveying Prism, consider the offset, the thread size, and the size of the prism itself. When working with Total Stations that require a target or reflector, a Surveying Prism is a must-have. Some Prisms are used on the top of a Prism Pole, while some are made to be mounted to the top of a Tripod. Most Surveyors Prisms have a 5/8 x 11 thread size although some use adapters instead of threads such as the Leica Adapter type. Mini stake-out type prism are smaller in diameter which allows the user to get close to a wall or building to get the shot or stake out. The key to buying an accurate prism that will last is going with a quality brand name, which leads to better machining, and better optics. Some prisms, as mentioned, are used on top of a surveyors tripod which can be used for back-sighting purposes as well as increase accuracy even further.

Prism Range
Surveying Prisms, also known as retro-reflectors, redirect a measuring beam back to the EDM (Electronic Distance Measurement) for processing distance.  There are two main factors for good range measurement: prism diameter and beam deviation. If the beam deviation is not accurate then the returned beam will miss the EDM completely. This occurs mainly near the maximum range of the EDM. Keep in mind that all Seco standard prisms are <5 seconds. 

Prism Holder Accuracy
Prism accuracy is determined by the physical location of the prism in its canister and then to the prism holder. Certificates of compliance are available upon request. Seco prism accuracy is 1 mm or less.

Survey Prism Offsets
Some Surveying Prisms have an offset due to the fact that the transmitted beam from the EDM takes longer to enter and exit the prism.  The longer time translates to a longer distance measured. The distance is corrected by using an 'offset' and/or positioning the prism in relationship to the plumb line of the prism holder. Common offsets are 0, -17.5 mm, -30 mm, -34 mm, and -40 mm. The offset is determined by multiplying the height of the prism against the refractive index of the glass used.