At focus compressed 7 and 70 femtosecond pulses for deep tissue multiphoton microscopy

We compare the contrast, signal intensities and excitation selectivity of a standard Ti:Sa Tsunami oscillator laser typically used in multi-photon microscopy with about 150 fs pulse duration and compare the performance with an... [ view full abstract ]

We compare the contrast, signal intensities and excitation selectivity of a standard Ti:Sa Tsunami oscillator laser typically used in multi-photon microscopy with about 150 fs pulse duration and compare the performance with an ultrashort laser source with 7 fs short pulses. Pulse compression and measurement was performed at the focus of the objective with a new microscope compatible with the d-scan laser metrology based transmission head.
Using such pulse compression technique we were able to reduce the Tsunami pulse length at the focus of the objective that mainly is affected by the dispersion of the high NA (1.4) microscope objective itself and obtained nominal Fourier Transform limited pulses with 70 fs pulse duration at the position of the sample.
We use a multicolor-labeled 2D FluoCells® (Thermofisher) test sample as well as a pig artery tissue sample to compare contrast, intensity and in addition the deep tissue imaging performance and can report substantial improvements of these parameters using at-focus compressed femtosecond laser pulses. These improvements could play a major role for rendering multiphoton microscopy an excellent tool for noninvasive optical investigation of bioengineered tissues and to drug delivery studies inside tissues.