Laser technology has been in use in medical surgery but new methods continue to emerge. Now laser-based diagnostic devices are proliferating in biomedical imaging and biological research as well. And the credit goes to Ultrafast lasers which made the things possible.
Optical tomography uses ultrashort laser pulses to detect abnormalities within the body. The ultrashort pulses work well as the human tissue is translucent. At a wavelength of 8nm tissue transmits one-third of the radiation over a distance of about 10 cm. The most advanced optical tomography which has been developed till now is a MONSTER. Multichannel Opto-electronic Near-Infrared System for Time-Resolved Image Reconstruction(MONISTER) MONISTER has diverse applications ranging from the scanning of human breast tissue to heads of newborns.
The instrument sends picosecond-long pulses of light from a Ti: sapphire laser through a series of optical fibers so that the point of illumination changes sequentially. Eventually, 32 bundles of optical fibers collect the scattered light. the instrument builds up 1024 plots of photon path lengths, each representing the connection between a given point of illumination and a detector.
Laser speckle Flowimetry
The laser speckle flowimetry detects changes in the blood flow within tissue. Herein, laser light is scattered by moving blood cells. On the other hand, the static tissue s scatter light with unchanged frequency. The resulting speckle pattern varies due to light waves interference. As a result, the detector measures the variation in the speckle pattern due to rapid blood flow.
The development of all-solid-state systems has brought high-performance lasers within reach of smaller research laboratories. Fluorescence lifetime imaging (FLIM) uses short laser pulses in the femtosecond to picosecond range. The technique excites fluorescence signals in biological tissues. Recently, a system for FLIM has been developed that is entirely solid-state, inexpensive, and portable. The system generates 45-ps, 1-µJ pulses with a 5-kHz repetition rate at 860 nm.2 These pulses are then frequency-doubled to 430-nm pulses at 22 nJ. A CCD camera records the return fluorescence signal, and the computer measures the decay times for each pixel, fitting the decay curves as an exponential with fast and slow components.