HI,
I'm starting a project and I need a type of light detector for a laser so that when I point my laser on the light detector (which will be on a target) it activates and sends a signal to my transmitter. Then, the transmitter transmits a signal to my receiver 100 yards away and then the receiver activates an LED next to me at 100 yards away.
Any ideas on which light detector I could use?
Thank you,
What is the wavelength of the laser?
chances are a CCD video camera will work. not your cellphone camera, which is typically CMOS. most digital still cameras and video cameras are CCD. most Arduino camera modules are CMOS
start with a an older camera you can afford to waste. point a known working remote at it and press a button. if you see a flickering light on the remote it's a CCD camera
For typical laser pointer diodes almost any photo diode or red LED should work as a receiver - find out yourself. For protection against ambient light the IR remote approach with a carrier frequency of about 40kHz can be used, or one of those ready-made IRremote receivers for IR senders.
Pointing at a target requires a very narrow beam, else the detector will yell with every signal sent out into an arbitrary direction. That's why I suggest one of those cheap and somewhat safe 5V laser diodes which produce a few mm diameter spot 5m away. For narrower beams you have to pay much more, in addition to the laser itself.
groundFungus:
What is the wavelength of the laser?
630-680nm . Also, If I use a photodiode of 940nm is it good or do I need a photodiode of 630-680nm too?
Most photodiodes detect a broad range of wavelengths, but LEDs used as photodiodes do not. Always look at the photodiode data sheets -- they will tell you the usable wavelength range and expected sensitivity over the range. For example, the popular BPW34 photodiode (see below) works pretty well at 650 nm. It is best to have a filter over the diode that matches the laser wavelength, otherwise background near IR radiation may swamp out the signal.
The data sheet of a photodiode includes the spectral sensitivity curve. A 940nm diode will also detect 680nm light, only with lower sensitivity.
DrDiettrich:
The data sheet of a photodiode includes the spectral sensitivity curve. A 940nm diode will also detect 680nm light, only with lower sensitivity.
Also, is it possible to use one arduino for a transmitter and receiver? I would preferably want me to point the laser from 100 yards away on the photodiode and when I do that the transmitter sends a signal to the receiver and the receiver sends a signal to a LED that ligths up next to me at 100 yards from the photodiode when the laser points on the photodiode.
If you want to do all that based on wires, the transmission lines deserve some line drivers and consequently their own controllers. Using Wifi or like that a controller is required at each station. I'd go for the wireless model...
DrDiettrich:
Using Wifi or like that a controller is required at each station. I'd go for the wireless model...
But not if you need to use synchronous detection to identify the transmitter against ambient light. If you just use a 38 kHz detector or similar that would not matter.
Remote control at 38kHz does not require any synchronization between sender and receiver. It's not a synchronous protocol that would require exact recovery of the carrier frequency and phase. The carrier frequency simply allows to separate the signal from ambient noise, just like done in every RF receiver.