THORLABS SL1325-P16, Руководство по эксплуатации

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Swept Source Laser
14138-D02 Rev F 04/17/09 Page 8 of 18
2.2. Components
Packing List
The SLXXXX-P16 system is a self contained laser system, it does not need any additional equipment or instrument
or controls to be connected in order to operate. Please refer to the packing list below to ensure that the system is
complete. If any item is missing or damaged, contact Thorlabs for assistance.
Components Quantity
Swept Source Laser Module 1
Power Cord
(1)
1
Manual 1
(1)
Power cord supplied for use in North America only.
2.3. Operating Principles
What is a tunable laser source (TLS)?
A Tunable Laser Source (TLS) is a laser whose output wavelength could be swept (continuous or random access)
over a certain, and usually quite wide, wavelength range. The SLXXXX-P16 can be tuned over typically 85nm.
TLS’s are frequently used in various measurement applications where a recording of a certain measure versus
wavelength is performed. Each application requires detailed knowledge on some or all parameters characterizing a
TLS (
e.g.
wavelength range, side mode levels, spontaneous noise levels, line width, sweep characteristics).
Thorlabs’ Frequency Swept Tunable Lasers are specifically designed for Swept Source Optical Coherence
Tomography (SS-OCT) and Optical Frequency Domain Reflectometry (OFDR) applications. These applications
provide real-time, high resolution, cross-sectional imaging of turbid media and require a specially designed laser
source that can sweep a wide wavelength range at very high speeds. A wide spectral tuning range is required for
high axial resolution OCT images, and a high sweep-speed is needed to obtain real-time 2D and 3D OCT imaging
speeds. Thorlabs now offers a variety of frequency swept laser sources based on a tunable external cavity
semiconductor laser, designed and optimized for SS-OCT and OFDR applications.
Basic operation
SLXXXX-P16 is based on external cavity laser geometry. This external cavity laser consists of a single gain
element where one facet of the element serves as an end mirror for the cavity. The extended cavity is comprised of
a single collimating lens and a Cat-Eye wavelength selection device. The intra-cavity side of the semiconductor
gain element is AR coated, providing a residual reflectivity of less than 10-4 thus allowing for the efficient formation
of an extended cavity. Wavelength selection is achieved using a diffraction grating mounted onto a scanner with a
focusing lens, mirror, and slit assembly providing active wavelength selection. The focusing lens and slit/mirror
assembly are separated by the focal length of the lens. This configuration is commonly referred to as a Cat-Eye and
is highly insensitive to angular misalignment. Output from the laser cavity is coupled into a fiber using a lens system
containing an isolator (SL1325-P16 only) that prevents optical feedback into the cavity. This design enables a
robust alignment due to the cat's eye configuration of the back-reflector which provides superior long-term stability
compared to designs with a quasi-collimated beam on the laser cavity back-reflector.