FTMC50-SCL
Overview
Light from the supercontinuum laser enters the FTMC50-SCL through a socket into which the output ferrule of the laser is slotted. A dynamic beam expander increases the beam diameter to a minimum level that prevents damage to the diffraction gratings, or, if required by the user, up to 12mm. This beam is filtered by one of 6 filters on a rotary filter wheel, then diffracted by one of three gratings mounted to monochromator turret, and the chosen diffractive order is captured and focused onto the output slit using a mirror. The output slit sets the bandwidth. The light diverges again beyond the mirror and then is reflected off a final collimating mirror, coupling the light to free space.
Alternatively, the output slit / collimating optic can be replaced using a precisely positioned fibre mount. The combination of grating ruling density and the aperature diameter of the fibre then determines the bandwidth.
Beam Expander
The device features an internal dynamic beam expander that compensates for the wavelength dependent beam width of the SCL laser beam. This protects the gratings from laser induced damage, and produces an output beam with a user-controllable, wavelength-independent output beam diameter. It can also be used to correct for a wavelength-dependent input beam diameter.
The video on the left shows this device by itself.
Software Control
The FTMC50-SCL is a smart device that contains all of its calibration data, as well as the algorithms and calculations required to reconfigure itself for a certain wavelength, so minimal work is required externally. To further simplify the control scheme:
- The USB device class is HID, which does not require drivers in any modern operating system, as it is the same class of device used by keyboards and mice.
- The command protocol consists of SCPI-style text-based commands that are very readable. For instance, you can turn your FTMC50-SCL to 555nm using the command "GOTO 555".
- No Bentham software is required on the host computer, but we do provide some software to simplify things. For instance, we publish a crossplatform Python package bendev, which is open source, available with the permissive MIT license, and can be installed with "pip install bendev". A windows SDK with a simple control library and a terminal is also available.
