Interview process was normal for this type of position: recruiter phone screen, hiring manager online interview, online technical interviews, in-person technical interview.
I have been hiring for 10 years at two different companies and Lightmatter have thoroughly impressed me and have completely changed my perspective on the hiring process. It is clear that Lightmatter want their candidates to succeed, respect their candidates, and want their employees to succeed. Despite not working there, in my opinion this is a source of Lightmatter's success. The fact that Lightmatter gives interviewing candidates pointers on what to study is truly remarkably respectful. I will take Lightmatter's approach going forward in my career.