Achromatic reconstruction of the wave front of femtosecond laser pulses D. A. Dement’ev N. N. Andreev Acoustics Institute, 117036 Moscow, Russia A. L. Ivanov, O. B. Serov, A. G. Stepanov, and S. V. Chekalin a) Institute of Spectroscopy, Russian Academy of Sciences, 142092 Troitsk, Moscow Region, Russia A. M. Smolovich Central Office of Design of Unique Instrumentation, Russian Academy of Sciences, 117342 Moscow, Russia Submitted 10 January 1997 Pis’ma Zh. E ´ ksp. Teor. Fiz. 65, No. 5, 388–390 10 March 1997 Wave-front reconstruction by geometric-optical reflection of the recon- structing radiation from interference surfaces of a structure recorded in the bulk of a medium by counterpropagating laser pulses is observed. The recording is done with the aid of a sapphire titanate laser. Pulse durations of 30–40 fs are used. © 1997 American Institute of Physics. S0021-36409700505-7 PACS numbers: 42.40.Kw, 42.15.Dp, 42.40.Ht This paper reports an experimental check of the following mechanism of wave-front reconstruction. 1 Let the interference pattern of the object A 0 ( r)expikL 0 (r)  and reference A R expikL R (r)  waves, satisfying the scalar equations of geometric optics, be recorded in a bulk medium. Here k =2  /  is the wave number and  is the wavelength of the radiation, L 0 ( r) and L R ( r) are the eikonals of the waves, A 0 ( r) and A R are the ampli- tudes of the waves, and r is the coordinate vector. Under the conditions of geometric- optical reflection of the reconstructing wave A C expik'L R (r)  from the surface of con- stant phase difference of the object and reference waves L R  r -L 0  r = p , 1 where p is a constant for a given surface, the phase k ' L refl ( r) of the reflected wave on this surface equals the phase of the incident wave k ' L refl  r =k ' L R  r . 2 It follows from Eqs. 1 and 2 that L refl  r =L 0  r + p , 3 i.e., to within an additive constant, the eikonal of the object wave is reconstructed for an arbitrary value of the wave vector k ' . Hence follows achromatic reconstruction of the wave front — the surface L 0 ( r) = const. 402 402 0021-3640/97/050402-03$10.00 © 1997 American Institute of Physics