Sub-nanosecond laser pulse contrast measuring device

The invention discloses a sub-nanosecond laser pulse contrast measuring device. In the measuring device, a measured high-power ultra-short laser pulse square light beam is converted into reflected light and transmitted light after passing through a spectroscope, and the reflected light is changed into a series of convergent laser pulse strings with fixed time delay after passing through a pulse delay device; the laser pulse strings and transmission square light beams are simultaneously projected to frequency doubling crystals for frequency conversion so as to form a plurality of self-correlation signals which have the same spacings up and down and fixed time delays between each other after passing through the frequency doubling crystals; and finally, the mixed light passes through an imaging lens to be imaged into a CCD to be collected and processed to obtain the pulse contrast information with sub-nanosecond time recording length. The device is wide in time recording length, low in cost, simple in structure and convenient to adjust.