Multiphoton Non-linear Optical Microscope (NLOM)

Almost ready!

This custom built, advanced NLOM is utilizes Zeiss AxioImager inverted microscope and a pulsed laser with extremely short (~ 10 fs) pulses (see Fig. 1) to simultaneously excite a broad range of fluorochromes. Another imaging modality is Second Harmonics generation (SHG), useful for instance for imaging of collagen. The NLOM has three non-descanned detectors. Pulse broadening effected by the microscope optics is compensated  by pre-chirp mirrors.

Figure 1. Pulse width characterization using an autocorrelator. The number of fringes permits calculation of the pulse width, here it was measured as 9.9 fs.

The ultra-short pulses (10-100x shorter than most commercial systems) provide two advantages: higher peak power without excessive photodamage, and broad-band excitation (spectrum width over 120 nm, see Fig. 2) that permits excitation of many fluorochromes without the need for laser tuning.

Figure 2. Emission spectrum of the femtosecond laser in mode-locked operation

The NLOM is being built in collaboration with Dr. Alvin Yeh (Biomedical Engineering). Currently it is physically located in Dr. Yeh's lab. Once the system is operational, it will be made available to users. Stay tuned for updates.  For more inforamtion, contact Stan Vitha (vitha@mic.tamu.edu).

Current status:

Optical path completed. Optimization of dispersion compensation in progress. Image acquisition software near completion. Imaging is now possible.

Figure 3: Second Harmonics signal from collagen fibres form rat tail tendon. 20x/0.7 dry objective. 65 mW laser power.