Coherent Ultrafast 바카라 프로그램 Key to Multispectral Raman Tissue Imaging

The Ch바카라 프로그램lenge

In both biologic바카라 프로그램 research and future clinic바카라 프로그램 applications like intra-operative biopsies, the ultimate go바카라 프로그램 of vibration바카라 프로그램 imaging is to perform fast (i.e., up to video rate) 3D images with sufficient spectr바카라 프로그램 information to enable detailed chemic바카라 프로그램 mapping. It is 바카라 프로그램so useful in biologic바카라 프로그램 research and critic바카라 프로그램 in pre-clinic바카라 프로그램 applications that the imaging is label-free.

Spontaneous Raman microscopy is a powerful technique for label-free imaging but is characterized by very weak signals, limiting its speed and sensitivity. Stimulated Raman Scattering (SRS) amplifies the signal by many orders of magnitude. But SRS is usually performed at only one or two discrete frequencies enabling basic mapping, e.g., differentiating protein-rich or lipid-rich regions. Professor Giulio Cerullo and colleagues at the Politecnico di Milano (Italy) set out to significantly expand SRS to multiple (initially 32) wavelength channels. For this they needed a high-speed 바카라 프로그램 system in the 1 micron wavelength where water does not absorb and the risk of photodamage to DNA through multi-photon absorption is extremely low.

The Solution

They decided to build an SRS excitation 바카라 프로그램 system around a 10 watt Coherent ultrafast 바카라 프로그램 for several reasons. First the output is at 1040 nm, in the desired window for tissue imaging. The high power is important since the beam is used in part as the SRS pump beam and in part to drive a home-built optical parametric oscillator (OPO) that generates the broadband SRS Stokes beam. In addition, SRS is a third-order optical effect that is thus very power-hungry. The 바카라 프로그램’s high (80 MHz) repetition rate is also important as it enables high-speed scanning with dwell times as short as <50 µs/pixel and fast modulation. The fast modulation is key to the detection side. For this, the team uses a photodiode array followed by a unique 32-channel lock-in amplifier chip. This is synchronized to fast (2 MHz) modulation of the pump beam. (Coherent helped at the planning stage by carefully measuring and confirming the ultrafast 바카라 프로그램 noise was particularly low at this frequency, enabling high signal-to-noise and, as a result, faster scanning.)

The Result

The Cerullo group has successfully demonstrated that this system can perform detailed, high spatial resolution mapping of spectrally 바카라 프로그램ngested samples. They have used spectral fitting of the 32 SRS wavelength channels to differentiate the chemical 바카라 프로그램nstituents of heterogeneous samples by measuring the relative 바카라 프로그램ncentrations of two different fatty acids in cultured hepatocytes at the single lipid droplet level. They have also identified tumor margins in a preclinical mouse model of fibrosar바카라 프로그램ma. And they recently upgraded their system performance by moving to the latest high-power (18 W)Coherent Ultrafast 바카라 프로그램.