Transverse up-conversion method for recording infrared radiation with picosecond time resolution

A description is given of a new method for recording infrared radiation with picosecond time resolution. The method is based on the conversion of the investigated infrared radiation to the visible range by a transverse interaction with an ultrashort pump pulse in a nonlinear crsytal. This method makes it possible to time-scan the investigated infrared radiation directly during conversion to the visible range. A theory is given of the nonlinear transverse interaction which produces the sum frequency. The theoretical relationships are supported by experimental results. Advantages and disadvantages of the proposed method are considered.