Autofocus functionality in optical sample analysis

A system comprising:

• a substrate to include a sample;
• a lens, wherein at least first light and second light from the sample are focused by the lens;
• a first filter to receive the first light and the second light focused by the lens, the first filter having a first surface reflecting the first light and transmitting the second light;
• a reflective component positioned on an opposite side of the first filter from the lens, the reflective component having a second surface reflecting the second light that was transmitted by the first filter, the second surface forming an acute angle with the first surface;
• and
• a sensor to receive the first light reflected by the first filter, and the second light reflected by the reflective component.

A method comprising:

• focusing, by a lens, at least first light and second light from a sample at a substrate;
• reflecting, by a first surface of a filter, the first light that was focused by the lens, and transmitting the second light that was focused by the lens;
• reflecting, by a second surface of a reflective component positioned on an opposite side of the filter from the lens, the second light that was transmitted by the filter, the second surface forming an acute angle with the first surface;
• and
• receiving, by a sensor, the first light reflected by the first surface, and the second light reflected by the second surface.