A very underestimated part of each surveyor’s toolset are prism poles. Prism poles in surveying are usually used in conjunction with total stations and various GNSS accessories. Also referred to as prism rods, they come in a variety of configurations and are created to keep the prism tight so accurate measurements can be produced.
With a good survey prism pole, a surveyor is able to produce precise readings in any type of field situation. However, elevating it to the proper height and attaching all the accessories does not mean that everything is done. There are various parts that you need to adjust and set properly to get as accurate results as possible.
Today, we want to tell you exactly which features to look for when shopping for one and how to properly set your prism poles for land surveying.
How to Use Prism Pole with a Prism?
Prism pole surveying might sound easy, but it requires people who are trained and equipped to do the job. Even though everyone can set up and use prism poles, there are a variety of things that you need to have in mind to create a proper setup.
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Setting Up the Prism Pole
To set up your prism pole properly, you first need to pick a proper location where you are going to place everything. It is preferable that you choose a level and stable surface. Adjust the height by extending it to the proper level. Make sure that the mechanism is locked so everything stays in place.
Take your 360 Prism and firmly attach it to the prism pole. Depending on the design of the prims, you will need to either screw it on or mount it via a quick-release mechanism. Secure the prism by fasting it tightly so it does not move during a survey.
Aligning the Prism
After setting up the prism pole the next step is aligning it properly. Use the built-in prism pole bubble level to align the prism so it stands perfectly horizontal. The prism needs to be in the line of sight of the total station, which may require adjusting the orientation of the prism pole. Finally, if you notice that anything is off, fine-tune the height or the angle so all the instruments are aligned with each other.
Taking Measurements
After setting the prism pole and aligning the instruments, you will be ready to take proper measurements. To do so, you need to make sure that the total station is connected and ready to take measurements. The important part is establishing a clear line of sight between the total station and the prism.
Each station comes with its own instructions, so depending on the one you are using, follow the steps to initiate the process. The instruments will then start to record the angle and the distance to the prism. Be sure to check everything while measuring. While most modern total stations log data automatically, it is still good practice to double-check everything during a survey.
Dismantling the Setup
After the measuring process is done, you still need to dismantle the setup properly and put everything away for safekeeping. Remove the prism first by carefully detaching it from the top of the prism pole. Then collapse the prism pole to a required height depending on how you plan to transport it.
Secure every piece of equipment that you have taken down and be sure to store the prism pole and the surveying prism itself in a dry and secure area to prevent any damage. Properly storing your equipment will prolong its lifespan and allow it to function properly during various surveys.
How to Pick a Prism Pole in Surveying?
Getting a proper prism pole will largely depend on the job that you are planning to do. There is no universal prism pole that can do it all, no matter if it’s a carbon fiber prism pole or an aluminum prism pole. Planning everything ahead will ensure that you select a proper one for the job. Here are the main factors that you should take into consideration.
Prism Pole Height
The primary factor based on which you will be choosing your prism pole is the height. Surveying rods usually come in three different heights, including 8.5', 12', and 15'. Depending on the surroundings, the terrain you are working on, and the scope of the job, you can determine the basic height that will work for you. But you also need to keep in mind that you have the option of using a mini prism pole, which is aimed at specific applications, including very hard-to-reach places.
Prism Pole Material
You can also pick your prism pole based on the material it is made of. The three options that you have are aluminum, fiberglass, and carbon fiber. Aluminum is the most affordable option of the three and is very lightweight, allowing you to carry it without so many problems around the job site. Fiberglass is more durable than aluminum but also comes with added weight. On the other hand, carbon fiber has the best characteristics of both, being both light and durable. But it does come at a greater price.
Fixed Tip vs Adjustable Tip
Probably the most important factor, as many professional surveyors would agree, is picking between a fixed and an adjustable tip. A fixed tip allows you to make accurate vertical measurements. However, if overall accuracy is what you need or you happen to be working with multiple prisms at once, a far better choice would be picking an adjustable tip.
FAQs
Find out more about prism poles in surveying through some of the following answers.
What is a prism pole?
A prism pole is a surveying tool used to hold a prism reflector, which is a device that reflects a laser beam back to a total station or other surveying instrument. The prism pole is typically made of aluminum or fiberglass and is designed to be lightweight and durable.
How does a survey prism work?
A survey prism works by reflecting a laser beam back to its source, typically a total station or other surveying instrument. This reflection allows the instrument to accurately measure the distance to the prism.
How to level a prism pole?
Leveling a prism pole is essential for ensuring accurate distance measurements. First, you need to extend the pole to the desired height. Then, attach the leveling device, but some prism poles already have a built-in one. Finally, adjust the pole by leveling the device on top of the prism pole while adjusting the legs of the pole until the bubble in the level is centered.
What is a pole in surveying?
A prism pole is a tool used in land surveying to measure distances accurately. It consists of a long, adjustable pole with a prism mounted on top. The prism reflects the signal from a total station, a device that emits and receives laser or infrared signals to calculate distances.
How long is a pole in surveying?
Survey prism poles usually come in three heights, 8.5', 12', and 15'.
How to calibrate a prism pole?
Prism pole calibration involves verifying that the pole's height and alignment are correct relative to the prism and the total station.
