Techtronix. they were the primary oscilloscope maker in late 1900s, that was until oscilloscopes could be designed and manufactured in China for a few hundred bucks.
nowadays they seem to still pursue high end oscilloscopes, where they focus on increasing the sampling rate from 500 MHz (with cheaper oscillioscopes) to 200 GHz.
I still don’t know how they’re still in business. The entire model seems unsustainable to me given that one of those oscilloscopes go on upwards $200,000.