In the field of endoscope optics we see more and more zoom designs, realized by tuneable lenses, micro actuators or traditional lens movement in rigid endoscopes with a camera sensor. For such devices, a lighting concept that adapts the beam angle to the current field of view of the zoom optics is desirable. In endoscopes, the light is usually transported from a source to the tip by a light guide or fiber bundle.1 Since it is not feasible to place an optical system at the fiber exit to fulfill the task, one would make use of the fact that a fiber roughly conserves the angular distribution of incident light and transfer the task of variable beam generation to the light source.
We present an optical system that performs this task by conventional optical means outside the endoscope. A LED is imaged to the fiber entrance by a system of variable focal length. By choosing the source etendue equal to that of the fiber, it is ensured that the proper magnification of the imaging is accompanied by the specified angular extent. The LED light is first collimated, and the exit pupil of the collimator is imaged by a system of moving and fix lenses. In a final step, we show a design to adapt a colored light source to the variable beam optics.
Diode lasers providing nanosecond optical pulses with high peak optical powers are key components in systems for freespace communication, metrology, material processing, spectroscopy, and light detection and ranging (LIDAR) as employed for, e.g., autonomous driving. Here, we report on laser sources for line-scanning automotive LIDAR systems. The laser sources are implemented as distributed Bragg reflector diode lasers bars featuring 48 broad area emitters each with a 50 μm wide mesa structure. The epitaxial layer structure comprising an AlGaAs-based waveguide and InGaAs single quantum well is optimized for pulsed operation at a wavelength of around 905 nm. For a temperature-dependent wavelength shift as low as approx. 60 pm/K, each emitter features a surface-DBR grating. The DBR laser bars are mounted p-side down on CuW submounts and sandwiched between a thin electronic driver board and a mount to minimize inductances. The in-house developed electronic driver generates 2 ns to 10 ns long current pulses with peak current up to 1000 A. With 8 ns long optical pulses and a peak current of about 900 A, a peak optical power of about 640 W is achieved at 25°C. Integration of the diode laser with micro-lenses and a beam twister provides a homogeneous line by individual projection of each of the 48 emitters with divergence angles of 24 deg x 0.1 deg (full width at 1/e2 intensity) in the vertical and horizontal direction, respectively.
KEYWORDS: Semiconductor lasers, Micro optics, Tolerancing, Assembly tolerances, Collimation, High power lasers, Control systems, Laser bonding, Active optics, Optical alignment, High power diode lasers
The industrial assembly processes for fast axis collimation (FAC) lenses with high power laser diodes are continuously being improved and automated. The system requirements allow for various solutions for the attachment process of the micro-optic component, the standard being active assembly relative to the light emitting laser-diode facet with joining by a UV-curable glue at attachment positions outside of the laser beam-path. To facilitate higher degrees of freedom and to optimize the results in the joining process with tighter tolerances in some critical functions, the FAC mounted on tab is one of the possible solutions and a viable process option. We report the results of high accuracy preassembly of FAC on tab with respect to the specific requirement of a target assembly back focal length within tight tolerance values.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.