I just started to get familiarized with Arduino, so I decided to get the Uno board. I've done some reading on sensors and for my first project I want to be able to get close range direct measurements by using a transmitter and a receiver as two separate units placed one in front of the other. I want the receiver to be able to read the signal accurately from short distances (as close as 0cm or 1cm and as far as 10cm or 15cm) to the transmitter.
I've found a single transducer ultrasonic ranger that can measure distances to targets as close as 0cm (Devantech SRF01 SRF01 Ultrasonic range finder ). I would like to know where can I get something like this as two separate units or if it would be possible to split it up into a transmitter and a receiver.
I also found the following separate ultrasonic transmitters/receivers (400ST/R100 http://www.robot-electronics.co.uk/datasheets/t400s10.pdf). However, I don't think they are capable of measuring ranges as short as the single transducer head mentioned above, correct?
The ways that I know of getting this type of direct measurements are: Ultrasound, infrared, and laser line. Are there any others? What type should I use? Which transmitters/receivers do you recommend?
The smaller the length and width of the transmitter and receiver, the better.
Any comments or suggestions are appreciated, thank you.