How to Choose the Right Survey Prism for Your Surveying Needs?

Picking the right survey prism for your task will impact the results of your surveying needs. Without a quality prism, or specific prims for the task you are doing, you cannot really hope to get accurate results and dependable results. The ability of a surveying prism to reflect a signal largely depends on numerous factors.  

One of them is the quality of the materials of a specific prism. But it also depends on how well you are taking care of it while not using it. There is the factor of your tool being able to withstand the harsh weather conditions during prims surveying that a lot of people might be disregarding as well

These are just some of the factors that you need to keep an eye out for before picking the right prism for the job. But let’s get into more detail and explain how things should work.

What Makes a Survey Prism a Good Prism?

The main characteristic of a good surveying prism is its ability to reflect as much of the signal as it receives. To improve the accuracy as much as possible, users need to make sure to protect the prism as much as they can and also make sure that they have a well-made one for their specific use.

Primarily, it should be able to cope with the distance you are measuring. If not, the results are not going to be trustworthy at all. Depending on whether you are measuring short or long distances, a different coating for the prism will be used. Additionally, it has to be robust and come with good enough protection so if the survey prism pole falls on you, it is still capable of staying in one piece.

The perfect prism is usually the one that has the best quality control, is created with strict assembly, and maintains sophisticated production techniques.

Prism Alignment to Prevent Beam Deviation

Prisms are made from a glass block, and the way the glass used in prism production is made helps in reflecting the signal back to its source. The very process of cutting, mounting, grinding, and polishing directly affects the amount of EDM signal that is returned from the reflector to the total station.

The more accurate the surface of the glass is as well as the corner angles, the better the quality of the returned signal is, as well as its intensity. If the angle is even only a few seconds off, the return signal will miss the instrument, resulting in not being able to measure the distance at all.

Special Coatings to Improve Performance

The type of material a prism is made out of greatly affects its reflective ability. For instance, copper is a very good reflective material as it offers excellent reflectivity across many EDM wavelengths and it also does not corrode.

An anti-reflex coating can also be added to prevent errors at close-range measurements. Prisms without this type of coating can often cause errors at short-distance measuring. This is because of the front of the prism which directly reflects a certain percentage of the signal, making room for false results to be produced.

Centering Accuracy

The quality of the prism can be also measured based on its centering accuracy. This reflects the alignment and proper placement of the prism in its holder and mounting stud. If you decide not to use the original prism holders, there is an increased chance of measurement errors occurring. Even though there are a bunch of Leica-like holders available, they may not be suitable for accurate use with an original Leica survey prism. 

Weather-Proofing to Avoid Feflector-Blindness

Not sealing the prims properly may cause the surrounding elements, caused by the weather conditions, to come inside and destroy the prism’s ability to reflect back a signal. Prisms used in monitoring surveys are usually left in the field for prolonged periods of time. To be able to do this, they need to be created so they can withstand the outside elements during various situations.

Some prisms may include up to three layers of protection, along with copper coating. They usually come with an adhesive coating that helps to fix the copper coating to the glass. A protective coating is there to protect the copper layer, while a lacquer helps to seal everything together. The final touch is the antireflective layer placed in the front, which helps to provide additional protection from potential environmental influences.

Factors to Consider When Choosing a Surveying Prism

A survey prism is an essential tool used in mapping and various types of surveying organizations, therefore making the selection of these tools an important starting point for every land surveying professional. 

The main thing to consider is the material it is built from. Materials that are durable and resistant to wear and tear the more preferable. This does not only ensure the accuracy of the prism but its longevity as well. You will be able to use it for much longer and it will also be able to provide you with accurate results during all kinds of weather conditions.

You also need to consider the size and the shape of the prism. The size needs to be appropriate for the specific application you are planning to use it for. Larger prisms are more suitable for long-distance measurements while smaller ones are best suited for close-range work. Also, different shapes can give you an advantage depending on the surveying task you are planning on doing.

There is also the accuracy and precision of a surveying prism that needs to be accounted for. Precision measurements require a high level of accuracy. This makes the collected data dependable as it can be used during various mapping projects.

Finally, ease of use is something that definitely requires consideration. Those that are user-friendly, lightweight, and portable make it easier to use and transport in the survey field. It also helps surveyors work more efficiently compared to having more heavier and robust types of equipment.

Risks of Using a Poor Prism and How to Spot a Fake

Using poor-quality surveying prism accessories can have a direct impact on your work. A badly constructed prism will produce wrong results and prevent you from getting the accurate measurements that you need. Even in some types of surveys where there is a broader range of accuracy and where measurements are taken in centimeters rather than millimeters, poorly constructed prisms simply won’t do.

Therefore, getting quality equipment is something that will definitely help you get to the best possible measurements. Original prisms always come with a unique security code on the box, guaranteeing their originality and proper function. You can verify a product and determine its proper function, and that way know exactly that you bought a reliable product.

FAQs

In the end, consider some frequently asked questions that you can establish before getting your next surveying prism.

How does a survey prism work?

Survey prisms are optical devices used in surveying to enhance the accuracy of distance and angle measurements by acting as retro-reflectors. When a total station emits an infrared beam, the prism reflects it back, allowing for precise distance calculations. 

What is a survey prism?

Survey prisms are specialized optical devices, specifically designed as retro-reflectors or corner reflectors, used in surveying to reflect signals from Electronic Distance Measurement (EDM) devices like total stations. They enable precise distance and angle measurements by reflecting infrared beams back to the source, minimizing signal scatter for accurate readings over long distances.

How to use a survey prism?

To use a survey prism, first gather your materials, including a surveying instrument (like a total station), a prism, and a surveying pole. Set up the instrument in a location with a clear line of sight and level it using the built-in bubble. Attach the prism to the pole and position it vertically at the desired survey point. Aim the instrument at the prism through the eyepiece, adjust the controls to center it, and record the distance and angle measurements.