Patent ID: 6191861
Filing Date: 2001-02-20
Classification: G01N

Abstract:
A chirp-free method for measuring the transient absorption of a material, said method comprising the steps of:a. generating pulsed laser beam to serve as a pump beam;b. generating a broad band pulsed laser beam to serve as a probe beam, said probe beam having a spectrum of wavelengths;c. passing said pump beam through a means for varying the path length of said pump beam;d. synchronously modulating said pump beam;e. directing said modulated pump beam and said probe beam through said material to produce a modulated signal on said probe beam;f. dispersing said wavelengths of said modulated probe beam;g. collecting said dispersed wavelengths of said dispersed probe beam; andh. simultaneously compensating for chirp between different wavelengths of said dispersed probe beam by varying in a controlled manner said path length of said pump beam to maintain a substantially constant time delay between said pump beam and said different wavelengths of said probe beam.