Figure 1: Biological laser optical setup.
The pump laser (Nd:YAG Pulsed Laser) with a pulse width of 5-8 ns which excites the gain medium molecules initially arrives at the optical parametric oscillator (OPO) where the wavelength of the laser is tuned in the visible spectrum by the help of a nonlinear beta barium borate (BBO) crystal. Power of the laser light coming out of the OPO is adjusted by suitable filters. Power adjusted laser light arrives at the dichroic filter where only the light of wavelength above a certain limit can pass through. If the right dichroic filter is chosen, only the pump laser will be reflected while the emission from the sample will pass through. In this way, the analysis of the emission from the sample will be easier since it is separated from the pump laser on the dichroic filter. Pump laser reflected by the dichroic filter will be reflected by the mirror and focused onto the sample by the microscope objective. Emission from the sample will be collected by the microscope objective, and reflected through the dichroic filter by a mirror. Since the chosen dichroic filter will allow the emission to pass through, it will arrive at the beam splitter without any change. The beam splitter splits the coming light into two pieces, half of the light passes through it, the other half is refracted by it. Thus, the emitted light can reach both the CCD camera and spectrograph. Sample image can be taken by the CCD camera with 0.03 nm resolution, and the emitted light can be analyzed by the spectrograph.
Pump laser: 10 Hz Quanta-Ray INDI pulsed neodymium-doped yttrium aluminum garnet
(Nd: YAG) laser with a pulse width of 5-8 ns
OPO: BasiScan optical parametric oscillator (OPO) (SpectraPhysics)
Spectrograph: Andor Shamrock 500i Spectrograph mounted with Andor Newton
Cooled Spectroscopy Camera with 0.03 nm resolution
Figure 2: a. Nd:YAG laser, b. Optical parametric oscillator.
Figure 3: Andor spectrograph
Optical Setup - Configuration 2
Figure 4: Biological laser optical setup which includes an incubator to grow cells in the sample during lasing experiments.
The second configuration of our optical setup includes an incubator built in-house. This configuration is the exact same setup of the first configuration, the only difference is the incubator. In this configuration, the pump laser arriving at the microscope objective is passing through the transparent incubator wall and excites the gain medium present in the sample. The emission from the sample is being collected in the same manner, the emitted light is passing through the transparent wall of the incubator and collected by the objective.