Light sensor to sense light level
CdS light-dependent resistors have realtively high sensitivity and are easy to use, but generally too slow to measure something only 1 ms in duration.  Sensors based on semiconductor diodes are probably the most appropriate.  There are also photo-multipliers, but those are more complicated and usually only appropriate when the light levels are very low.

Semiconductor diodes can be used two different ways to sense light.  These are forward mode where the diode is used like a solar cell, and reverse mode where light effectively causes leakage thrue the reverse biased diode.  Reverse mode is more linear, but usually needs considerable amplification to get a useful signal.  You can also get a phototransistor, which works like a photodiode but includes some transistor action to multiply the raw leakage current by the gain of a transistor, all in one device.

You also need to consider the spectrum of what you are trying to sense.  The particular wavelength may dictate a particular sensor.  Note that in a pinch LEDs can be used as photodiodes.  These usually respond to a narrow range of wavelength around what they emit in normal LED mode.