I want to use Arduino Uno with two IR transmitters and receivers to measure if the light barrier is blocked or not. With these barriers I want to measure the average speed or time between two barriers are blocked.
Are these IR transmitter receiver pairs ok and do they produce the 38 kHz by themselves or do I have to use some other way to make the frequency?
Anything else I have to consider?
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Are these IR transmitter receiver pairs ok and do they produce the 38 kHz by themselves
No and no.
These are designed for data it is not what you need.
What else you would recommend, for example?
You need a receiver based on the TSOP4038 those are designed for continuous operation. All the others have a maximum pulse limit and will stop working if you give them continuous pulses.
Grumpy_Mike:
You need a receiver based on the TSOP4038 those are designed for continuous operation. All the others have a maximum pulse limit and will stop working if you give them continuous pulses.
At some point they started calling it the TSSP4038.
See: IR Receivers | Vishay. The "presence sensor" modules are the ones you want; the only practical (non-SMD) ones are TSSP4038 and TSSP58038.
You also might want to try: http://arduino-info.wikispaces.com/InfraredBeamPair. More expensive but a lot easier to use.
Any 38kHz based sensor will have a latency few times 1/38kHz. So it depends how fast the barriers are blocked etc.