Laser Test Report
Each laser engine is shipped with a Laser Test Report document that demonstrates its performance per the tested specifications as well as other measurements important to system integrators.
Page 1 of the test report typically lists:
- The Serial Number of the engine, which matches the label physically on the engine.
- The Axsun Part Number of the engine, identifying its baseline configuration.
- Test Date and Test Operator details.
- The Firmware Version installed on the laser engine at the time of testing.
- A table of tested Parameters with resulting values compared against Min and/or Max specifications, based on the standard product configuration or on a customized basis per the sales quote or other customer communication.
Test results are gathered at the final inspection stage of the laser manufacturing process, immediately before packaging and shipping. Tested parameter names are generally self-explanatory and are measured with calibrated equipment such as oscilloscopes, optical spectrum analyzers, and optical power meters.
Engines which include an optional integrated k-clock will typically list a "MZI path length difference" parameter. This value is related to the OCT scan depth (i.e. ranging depth) which is determined by the difference in path-length between two fibers comprising a Mach Zehnder interferometer (MZI). The test report value is stated as the error in the fiber length difference as compared to a target difference needed to achieve the specified OCT scan depth (in air). There is a factor of 4x between the OCT scan depth (in air) and the path-length difference in the MZI, as well as a conversion for the index of refraction of fiber (n = 1.4675). For example, a tolerance of +/- 308 um on the listed MZI path length difference parameter converts to a tolerance in the single-sided OCT scan depth of +/- 113 um.
Page 2 of the test report shows oscilloscope traces of the instantaneous k-clock frequency, sweep trigger signal, optical power output, and k-clock signal for two consecutive laser sweeps. (For engines which do not include an integrated k-clock, the laser is tested with a separate test-system's k-clock hardware.)
O-scope traces have a red line highlighting the "Sampled Region": the subset of the total sweep period which is useful for high-fidelity SS-OCT image data acquisition. Some laser and k-clock specifications are measured only within the sampled region.
Values for the minimum, average, and maximum k-clock frequencies are listed along with the total number of k-clock pulses contained in the sampled region (red highlight). The Duty Cycle is the ratio of the sampled region to the total sweep period.
The black circle represents the active sweep trigger edge, indicating the start of the sampled region. The sweep trigger polarity and duty cycle can be adjusted by contacting Axsun Technical Support. This signal is available as an output from the OCT engine and/or Interface Board.
The Duty Cycle listed here is the emission duty cycle, e.g. the percentage of the total sweep period when there is non-negligible optical power being emitting from the laser. It will be higher than the sampled duty cycle listed on the Clock Frequency plot and its start and end are indicated by two red asterisks. Values are listed for the average power (Pavg) across the entire sweep, as well as the average (PavgBW) and peak (PpeakBW) powers confined to the sampled region (red highlight).
This signal is available as an output from the OCT engine and/or Interface Board for engines which include the integrated k-clock option. In addition to showing the amplitude of the k-clock signal inside the sampled region (red highlight), the O-scope trace also shows whether or not 125 MHz "dummy clocks" are enabled in the region of the sweep outside the sampled region. Dummy clocks are often required for glitch-free operation of some common digitizer boards when running in an externally-clocked fashion. Dummy clocks can be enabled or disabled by contacting Axsun Technical Support.
Dummy clocks enabled outside of sampled region.
Dummy clocks disabled. K-clock signal will disappear outside of the sampled region.
Examples of laser test reports for some standard configurations are shown below. Laser test reports for other engine types may include more or less information than what is shown, depending on specific product customizations, included options, and customer reporting requirements.
NOTE: The parameters and specifications listed below are for example purposes only and are not representative of all product configurations offered by Axsun Technologies. Please refer to the laser data sheet here or communicate directly with our Sales Team at [email protected] (978-262-0049) for more information on Axsun's laser capabilities and options.
A 1060 nm laser in Benchtop Enclosure (AXP50125-3) with 100 kHz sweep rate, 143 nm of tuning range, and 31 mW of average output power.
A 1310 nm Integrated Engine (Standard OEM Configuration plus Ethernet DAQ, AXP50124-17) with 100 kHz sweep rate, 132 nm tuning range, and 30 mW of average output power.
A 1060 nm Small Form Factor OEM engine (AXP50124-24) with 200 kHz sweep rate, 111 nm tuning range, and 18 mW average output power.