Wavelength, Nearfield, Beam Spread Calculations

[@JClasenCowleyNDT]

Hey Thanks, I never really thought people would watch them, I really added them for my students to watch in my classes and other have started watching to, which is great!

[@lukaszterlikowski5534]

Good job mate, 10 years later they are helping me with my study !

[@BGIS2000]

Learning lot of things by watching you educational videos, I wish you were still around and upload more videos. Thank you so much.

[@aerialrescuesolutions3277]

Excellent work there. Thank you, Jim

[@ericshifflett8251]

Great video, very informative. Thank you for sharing.

[@sjames666]

These vids are superb. Completed my UT Level 2 in March and I wish I had found these earlier. I've been watching them as a refresher and checking out the ones on Eddy Current as that is the next discipline I want to take. Very well explained and presented, thank you!

[@donalderickson3385]

Thanks I'm taking my level 2 test in two days. Never really thought I'd be using anything in math above simple algebra as an adult. The way you explained the beam spread was verry helpful thank you verry much.

[@RisingSonSpacelicker]

My dear gawd squire you're heaven sent I have a paper tomorrow and near field and beam spread have been kicking my ass

[@tristenjames8354]

All your videos are great...clear and concise and easy to understand...Thx:-)

[@Mdood]

Excellent videos your making, I'm watching them as I'm going to do my UT level 2 course soon and just getting a little heads up. Keep it up and thank you !!

[@JClasenCowleyNDT]

@Selvatice Sorry about the delayed response, yes you can use different values for the beam spread calculations. I have just always used 1.22 for my calculations.

[@goldstarcwi]

Do you have any videos with velocities in 10^5 cm/s and m/s being converted to mm?

[@DirtyLarry-x3k]

Write out the full numbers for meters or cm as they specify in the question (without scientific notation to keep it simple) and then convert to mm (by moving the decimal one space to the right for cm to mm, or by moving the decimal place three spaces to the right for meters to mm) and do the same as in this video for calculations with the numbers for Hz. To convert to inches at the end for the near field length, divide mm by 25.4.

[@davidmay3852]

Joe your video instruction is very helpful. Do your have any info on scanning tee welds at both attachment point and weld volume?

[@Selvatice]

Hi there! I have a doubt: The bibliography I have consulted states: sin @ = V/D.F x K, where K has differente values as follows: For straight beam probes: 0,51 to div up to -6dB 0,87 to div up to -20dB 1,08 to div up to -30dB And, in case of angle beam probes: 0,44 to div up to -6dB 0,74 to div up to -20dB It also says we should multiply the diameter of the crystal by 0,97 in order to find out its actual diameter. Could you help me to understand? Also: what is that 1.22? Many thanks!

[@tomz9c1]

Great stuff Joe! Thanks.

[@user-charlieccchong]

Joe! Thanks. Great as always.

[@ARCSTREAMS]

this is for monochromatic signal right,,but suppose i want to measure divergence of a collimated white light beam after it exits a collimating lens

[@darrenmitchell1792]

Thanks

[@joepaularmstrong7071]

Hello Mr Joe

[@plugsterplugster8635]

I dont get the same answer for the beam spread. 230000 ------------ 0.5 *5,000,000 =2.3 What have i done wrong?

[@Blockchain_BoxOffice]

Please can you work this out for me? Question: What is the beam spread half angle for probe of 1.25cm dia, and 2.25MHZ, in water (v=1.5km/sec)?

[@Blockchain_BoxOffice]

My answer is not on the options.

[@betrayable]

sinθ=1.22×(V/(D×F))；sinθ=1.22×(1500000/(12.5×2250000)；θ=3.73° V：1.5 km/sec = 1500000 mm/sec D：1.25 cm = 12.5 mm F：2.25 MHz = 2250000 1/sec

[@mohdnazmiabdazizabdulrahma4047]

thank you sir

[@anarakhundov885]

how I can calculate 20dB beam spread for following probe .0 deg 20mm 2MHz when testing steel? Thanks

[@joeclasen1977]

Anar Akhundov You can use this same forumula if you want. What are you wanting to know about it?

[@anarakhundov885]

I have calculated and got answer is 9.2 deg .but in the tests which i did answer is 18.4 deg

[@Cowleyelearning]

Anar Akhundov At that point what you would do is double the 9.2º because what you actually calculated is the 1/2 angle beam spread. Does that help?

[@harleythorp4532]

I have been told that beam spread is not real can you please give me your defence to this and try to debunk the video "sound is round" here on you tube

[@joeclasen1977]

Harley Thorp Sorry for the way late response, but I thought i would answer your question. Basically the way that it works is lik this. Sound technically isn't round, however since objects have to vibrate they do so in a wavelike formation which makes them round. So if you are thinking about a transducer for UT, what happens is the outside of the transducer is tied to the sides of the case, so then what you have is a flexing element that is tied on the sides creating a rounded sound coming out of the transducer making "rounded" waves. I hope that helps!

[@arigato021]

Think of your ultrasound going into a part being like a flashlight. Hold a lit flashlight in a dark room, stand close to a wall and point it at the wall. Note how big the circle of light on the wall is. Start to walk a few steps away from the wall while continuing to hold the flashlight in the same position. Notice how the circle of light on the wall grows in size. That's basically what ultrasound does in a material. That's the beam spread. It's real.