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What is Optical Measurement?

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  • Written By: Mary McMahon
  • Edited By: Kristen Osborne
  • Last Modified Date: 03 August 2014
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Optical measurement is a measurement technique that relies on the use of optical sensors to collect measurements. There are advantages and disadvantages that must be weighed when using devices capable of optical measurement. Several different types of systems are available, including fully automated ones, as well as systems that allow for more manual control for precision measurements. High end systems can be quite costly and are found in labs and materials testing facilities where exact measurements are critically important.

One advantage of optical measurement is that it is noninvasive. No contact is required, beyond contact with the stage of an optical measuring device. Probes do not touch the object being measured and the device does not rely on destructive measurement techniques. For many applications, there is a desire to keep items being measured intact throughout the process, and subsequently, optical measurement can be highly appealing.

This technique can also be very precise. The optical sensor is highly sensitive and can detect subtle gradations and other differences that might not be visible to someone using probes or manual measurement techniques. This allows for very accurate measurements. There are many settings where they can be important, like machining precision parts that have very low tolerances and must be produced with as few errors as possible. Optical measurement is also very fast once an item has been set up properly, with the device capable of taking multiple measurements at once.

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The primary disadvantage to optical measurement is that automated systems are not necessarily able to correct for errors that humans would be able to address. For example, if a flat part is being measured and there is a small burr along one side, the machine will read the burr into the measurement, while a person would note the burr and compensate during the measurement process. Computed numerically controlled (CNC) systems like those used for optical measurement in settings like quality control can be very adaptable, but they are usually not capable of making intuitive leaps like humans are.

The cost of optical measurement systems varies and they are designed for different uses. Companies that manufacture such systems can provide information about the applications their products are most suited for, as well as offering information about warranties, performance, and other features that might be important to prospective buyers. Many companies also allow people to interact with their equipment before sales are finalized. This gives people a chance to practice and test out new equipment.

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SkyWhisperer
Post 3

While I think the idea of non invasive optical measurement would work in a lot of applications, I don’t think it would work for things like weighing an item or determining an object’s mass.

I don’t believe that you could get those measurements by using optics alone. However, for general length, width, height and stuff, I think it would work.

Charred
Post 2

@Mammmood - I work in software development and I think I can have an answer to one of the problems with optical measurement that the article talks about.

The article says that optical measurement is not precise, because it will look at the burr of a metal part and treat it as part of the image.

However, in computer science we have something called “fuzzy logic,” so called because it is designed to deal with “fuzzy” or close approximations of data. In other words, it deals with measurements and quantities that are not so precise.

I could see fuzzy logic fixing that problem with optical measurement. Don’t ask me how to do it, but I bet it would work.

Mammmood
Post 1

I think that optical measurement is probably used in digital camcorders for digital stabilization. I don’t know this for a fact, but it would seem to make sense.

With digital stabilization, the camera looks at the video image frame by frame and attempts to account for camera jitter and shake, producing a smoother video image.

From my experience it is not a perfect technology, but it does help. Purists will shirk away from anything that involves digitally tweaking an image, preferring pure optics instead, but I think it’s worthwhile.

I do stay away from the dreaded digital zoom however, which does nothing but stretch an image and make it look fuzzy.

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