A transient plasma micro optics (plasma channel and focusing plasma optics- TPMO) in the LWFA provides controllable electron self-injections that result in production of higher quality bunches. In recent study of the TPMO, the deep, straight and short-lived plasma channels [splash plasma channel] were produced by picosecond and sub-picosecond laser pulses in the ponderomotive force dominant regime. Various techniques were used to characterize those channels in argon gas jets irradiated by moderate intensity, ∼1015-16 W/cm2, laser pulses with their durations from sub-picoseconds.