One of the options to measure high temperatures would be to use thermocouples. This table provides a basic description of the types and the corresponding temperatures that they can sense.
A simple search led me to these components.
- Thermocouple Type-K Glass Braid Insulated - A mid range thermocouple
- Thermocouple Amplifier MAX31855 breakout board - Board to interface the thermocouple with the Arduino. This is needed as the voltage changes in the thermocouple are extremely small, and the rise is non-linear.
This is how the board is connected to the thermocouple.
There is also a tutorial on Adafruit that deals with using and interfacing thermocouples.
This is an image of the thermocouple interfaced with the Arduino.
