★LISER™ Light Source
Externally controlled, FC connectorized, broadband, surprisingly compact, literally "cool," and noticeably silent, the ★LISER™ light source generates high-intensity CW light or light pulses of set intensity profile and repetition rates. ★LISER™ stands for Laser-Induced Spontaneous Emission of Radiation produced when laser diodes focus on luminescent materials. It integrates the cooling system, laser diode and LED drivers, focusing optics, and electronic control interfaces with the ★LISER™ module and LED or Laser Diode modules. The ★LISER™ module focuses the light from 5 blue laser diodes within a small round spot on Ce:YAG crystal inducing it to emit 150 nm broad light spectrum centered at 560 nm. Initially designed for 200 µm core diameter optical fibers with a 0.53 numerical aperture, this light source is well-suited for other optical fibers having FC connectors. The fiber-coupled ★LISER™ module output power increases with fiber's numerical aperture and core diameter (<600 µm.) LED or Laser Diode modules provide additional spectral bands.
★LISER™ light source is computer-controlled with Doric Neuroscience Studio Software (V6 and higher) via USB port or by analog or TTL signals over respective BNC input connectors. All modules are independently controlled. The voltage signal at the output BNC connector, proportional to the module's driving current, is used for synchronizing the light source with other devices. The safety features include a rear-panel interlock connector and a master key switch. Two small white LEDs indicate the respective light module's activity. Unlike most commercial drivers, the drivers eliminate the leakage current and set the light output to zero, a crucial feature for optogenetics experiments. A filter slot cover lets the full ★LISER™ spectrum into the fiber. Any portion of that spectrum can be singled out by replacing the cover with an appropriate ★LISER™ Bandpass filter (LBPF).
The internal functioning of the light source is explained in this Laser Focus World article.
In neuroscience research, the high output power of the ★LISER™ light source is used for optogenetic activation and silencing opsin-labeled neurons and for excitation of fluorophores in fiber photometry over 200 or 400 µm core diameter optical fiber patch cords. e.g., Optogenetically Synchronized Fluorescence Microscope, 2-color Fluorescence Microscope, Bundle Fiber Photometry, and Optogenetics.
Elsewhere, the source can be used with 0.1 to 1 mm fiber core diameters to illuminate small diameter endoscopes, boroscopes, and other similar devices with its entire spectrum or parts of it.
Operation modes - Off
- External TTL
- External Analog
- Computer (USB)
Mass 2.6 kg Dimensions 20 cm x 15 cm x 14 cm Power supply 110 - 240 VAC, 50 - 60 Hz Optics ★LISER™ Wavelength range 500 nm - 650 nm Spot size at fiber tip 0.45 mm Optical Fiber Multimode
50 to 960 µm core diameter
NA 0.22 to 0.66
Optical Connector FC/PC receptacle Electronics TTL Modulation - HI > 2.8V
- LOW < 0.9V
★LISER™ Analog input voltage 240 mA/V (typical) LED Analog input voltage 400 mA/V (standard 1A LED) LD Analog input voltage 80 mA/V light source current Rise/Fall time >10 µs Modulation maximum frequency 50 kHz Software modulation types square, ramp up, ramp down, triangle
Typical ★LISER™ output power vs Optical fiber core diameter Typical Output Power (mW) Central Wavelength
Full Spectrum ~110 8.0 85 230 390 ★LISER™ 525 30 2.0 20 50 106
559 34 2.5 28 70 124 582 75 4.5 50 125 210 593 40 2.4 28 67 110 612 69 2.5 32 80 130 LED 470 25 0.4 6.5 26 120 LD 450 <3 75 75 75 75 LD 473 <3 70 70 70 70
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