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AlazarTech provides waveform digitizers (A/D boards) and software solutions that allow OCT users to digitize electronic waveforms generated by their MZI, perform real-time data transfer to GPU for DSP, and easily create live images in their custom imaging software.

Direct k-clocking

Direct k-clocking has been a popular method of acquiring data in an SS-OCT system. k-clock signal from the MZI is used by AlazarTech's A/D converter IC to acquire data that is linear in k-space. This saves an immense amount of FPGA or GPU resources that would need to be used to linearize the data post-acquisition. We have also heard from large volume customers that direct k-clocking is more stable from laser-to-laser than acquiring k-clock as an analog input and using it to linearize acquired OCT signal. Problems reported were instability of k-clock phase in the first 15 minutes of power up; and the need to do filtering of k-clock signal before using it for linearization. In all these cases, using "Direct k-clocking", i.e., using k-clock as the A/D sampling clock solved the customer's problem.

One popular complaint about k-clock being output by a swept source is that it is fixed in frequency and, therefore, limits the image depth. AlazarTech has developed dual-edge-sampling (DES) logic on its waveform digitizers that will effectively double the sampling rate and hence the image depth.

Cost benefits of Direct k-clocking include the possibility of using a lower cost A/D converter and lower cost FPGA

If your OCT system must operate on a 24/7 basis, you need to use AlazarTech products.

AlazarTech provides a complete solution for SS-OCT applications, including:

• Low Noise High Resolution data acquisition at fast sample rates With up to 4 GS/s sampling offered by ATS9373, you can future-proof your OCT system for tomorrow's sources
• Fast 6.9 GB/s data transfer rate for raw (time domain) data or FFT data There are OTHER companies claiming to offer OCT solutions, but their data transfer rate to computer memory is only a few hundred Megabytes per second, putting a ceiling on how many frames per second they can capture

• Support for variable frequency external clock to allow the use of the swept source's k-clock to solve the re-linearization problem This feature is unique to AlazarTech due to our unique A/D technology. Commercially available A/D technology requires fixed frequency sampling and, therefore, cannot use k-clock signals from swept sources. A DSP-based resampling scheme must be used to linearize the data in k-space. Our k-clock based solution directly generates data linear in k-space

• Unique OCT Ignore Bad Clock feature that allows use of out-of-specification k-clocks k-clock from many swept sources provide either no signal in between scans or a "dummy clock" of very slow frequency. In some cases, the "dummy clock" can also contain glitches. AlazarTech's OCT Ignore Bad Clock technology allows the user to tell the A/D circuitry to ignore the k-clock signal during a certain time duration after each trigger
• Complete On-FPGA FFT solution that includes:
•   User programmable dispersion compensation function
•   User programmable windowing
•   Log calculation
•   FFT magnitude output in floating point or integer format

• Special "Raw + FFT" mode that allows users to acquire both time domain and FFT data This can be very useful during the validation process
• Embedded data footers that include timestamp, frame count and many other useful information for each record