Sensor to detect an object going through a plane.

[CanOzbek]

Hello,

I need a sensor to detect if an object went trough a plane or not. The object is a cube with the dimensions of 1.5cmx1.5cmx1.5cm and the plane is a rectangle with dimensions of 2m x 1.5m.

Any help is appreciated.

Thank you.

 

[jiripolivka]

You can use a light beam or more beams aligned within your plane. If the object is opaque, light sensors on the opposite side can indicate passing object. If it is transparent, use reflection type sensors.
LED with lenses can be good, or try a laser like in pointers for beam narrowing.

 

[D.A.(Tony)Stewart]

- Visible light is OK but IR may be better.
- Steady IR may be OK but pulsed IR is better.
- Narrow emitter pattern is OK but narrow detector aperture hole is mandatory to prevent reflections off axis.
- Detector with AGC is best to compensate for variations in intensity with 50% threshold and pulse detector to confirm sender light.
- IR pulsed reflector is OK but prone to false reflections
- IR Pulsed Interrupter is best.

All of these are found in Remote control IR Receivers with visible light blocking filter and then mounted behind 5mm stepped black aperture deep hole with <10deg beam pattern

 

[RajivConfident]

In my robot I use steady IR but it can detect only nearrer object.I want to know how the air craft detect object at long distance.They use ultrasound?

 

[betwixt]

Ultrasound ! - they use RADAR.

Brian.

 

[RajivConfident]

Ultrasound is transmitted from the tower and the reflected sound is analysed then the size and the distance of the object is analysed.

 

[jiripolivka]

Ultrasound is transmitted from the tower and the reflected sound is analysed then the size and the distance of the object is analysed.

If you know so well how it is done, why you ask?
In fact, SODAR, sound radar is used in airports to detect fog and shear wind, not aircraft.
If you in Nepal use ultrasound instead of radar to detect and guide airplanes, the lack of radar explains many crashed airplanes over the years.

 

[betwixt]

RajivConfident, ultrasound is very difficult to focus into a narrow beam and the speed it travels is subject to air pressure and humidity. It's range is generally very short, a few hundred metres at best.

Airports use highly focussed rotating dishes that send pulsed microwave signals and according to the direction and time for an echo to return can calculate the distance and direction of an object such as an aircraft. The principle is called RADAR (RAdio Direction And Ranging) and is accurate, relatively immune to atmospheric conditions and works over many Km distance.

I have this vision in my mind of Pokhara airport having a huge trumpet spinning on the control tower roof, swatting the planes out of the air. :shock:

Brian.

 

[D.A.(Tony)Stewart]

- Visible light is OK but IR may be better.
- Steady IR may be OK but pulsed IR is better.
- Narrow emitter pattern is OK but narrow detector aperture hole is mandatory to prevent reflections off axis.
- Detector with AGC is best to compensate for variations in intensity with 50% threshold and pulse detector to confirm sender light.
- IR pulsed reflector is OK but prone to false reflections
- IR Pulsed Interrupter is best.

All of these are found in Remote control IR Receivers with visible light blocking filter and then mounted behind 5mm stepped black aperture deep hole with <10deg beam pattern

Which part of my suggestions do you not understand?

With a pulsed interrupter method with a 5mm IR LED and IR Rx set back in a 5mm aperture , you can measure a 1/4W resistor wire crossing the light beam path 1m apart from Tx to Rx using standard Sharp parts sold by Vishay now.

But to measure a hole you need it to be aimed a light shining thru at the right angle. Anything else will backscatter, disperse and find an unwanted path and cause false results.

It all comes down to how good you can do geometry and optics, not electronics, which is trivial by comparison.. Shine a flash light for starters and see accurate you can detect a hole then downsize it.

 

[RajivConfident]

In Nepal I don't know it is used or not But now I am clear about that.

 

[D.A.(Tony)Stewart]

10 seconds on web **broken link removed**

Now why detect a hole in a plane?

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