How to detect microwave or infrared radiation.

[avicenna]

Say I have created a strong enough micro and ir radiation source from a certain direction. I want a mini photocell/sensor to detect it. 

I know there are many mini photo diodes, etc available and cheap. But I need the sensor to be directional, having only one face to detect the radiation. If I flip the face, there would not be radiations detected. Also it should be easy to use, say just two leads to detect voltage/current.

Also, what electrical instruments do I need to detect a voltage/current. Can a common multimeter do the job.
 

[swansont]

Photodiodes are directional. Even more selective if there’s a lens in front of it, so off-axis rays can miss the diode. The casing is opaque, so flipping it won’t allow light in.

For microwaves you can build a loop antenna. A mask behind it would eliminate signal if it were flipped.

[avicenna]

Can you recommend a specific make of mini IR sensors. Say can detect 10,000nm IR. The sensor must not need external voltage source;, just two leads.

Loop antenna is too much for me to build!!!

 

Edited June 6 by avicenna
omission

[swansont]

2 hours ago, avicenna said:

Can you recommend a specific make of mini IR sensors. Say can detect 10,000nm IR. The sensor must not need external voltage source;, just two leads.

Loop antenna is too much for me to build!!!

 

10 microns is mid-IR, beyond the range of standard silicon photodiode; the energy is too low. You’d need a more exotic type, like HgCdTe, or possibly some other material. Hamamatsu is one company I recall that makes photodiodes. 10 microns is in the thermal IR range; bolometers are one detector that are used. Such as in IR cameras; I have one from FLIR that attaches to my iphone

Pickup loops can be purchased; I recall being shown one that were marketed to people checking their microwave ovens for leakage. (the person showing it used it to detect pulses from a step motor in a watch)

[MigL]

If you don't wish to build anything, there are, at least for infrared, 'off the shelf' cameras that can be purchased, which detect infrared sources and dispay them on a screen.
I used to use one for detecting integrated circuits that had failed ( or were close to failing ) and heating up due to excessive power draw.

Digital multimeters are available for $20 on eBay/Amazon for detecting low voltages and low currents on automotive or digital circuits.
If you are going to test for voltage/current on your mains or higher, I suggest something with good protection, like a Fluke.
The cost will be much higher, but there's nothing worse than testing a 300 or 600 volt circuit, and having your meter blow up in your hand and catch fire.

[John Cuthber]

https://en.wikipedia.org/wiki/William_Herschel#Discovery_of_infrared_radiation_in_sunlight

Or we may be talking bolometers
https://en.wikipedia.org/wiki/Bolometer

 

[avicenna]

I think I will search for what Swansont says about "loop" detector.

My problem is that my "aperture area" is very small, say 2x2cm view! I have little space to work with. I know of mini solar cells, but they dont detect IR waves. 

 

[swansont]

An issue with a loop is that it needs to match up with the wavelength of the signal you are trying to detect. A few cm should be fine for signals of order of a GHz or so (30 GHz has a wavelength of 1 cm) but as the mismatch grows the detector efficiency goes down.

 

[John Cuthber]

Incidentally, (I guess I'm late to the party but) I recently learned there's a name for this sort of question.

https://en.wikipedia.org/wiki/XY_problem
"The XY problem is a communication problem encountered in help desk, technical support, software engineering, or customer service situations where the question is about an end user's attempted solution (X) rather than the root problem itself (Y or Why?).^"

What problem are you trying to solve?

[Mordred]

If you know the frequencies your trying to detect you might also want to look into band pass circuits to filter out unwanted signals. Also RF signals are maximally detected via an an antenna at 1/4 wavelength. If your antenna picks up half the wavelength you get refective currents that will degrade your signal and cause equipment damage.

Optionally 3/4 wavelength is just as effective as 1/4.  

If you could provide more detail such as frequencies involved we may be able to help fine tune your components.

Edited June 6 by Mordred