I put my design together today. The design used is shown below, but has some issues still. General layout: slit on the left, baffle and grating / sensor array on the right.

A first spectrum can be found below.

Accomplished:

• Seems like the incident angle was pretty much perfect, aligning the red part of the spectrum to the center of the image
• the sensor array setup works nicely (compact unit)

Issues:

• focus, had to mess with the raspberry pi camera lens
• I didn't calculate the needed distance between the grating and the sensor as to maximize the used pixels (I admit, I was lazy). The small exit angles of the 300l/mm grating require a large distance from the grating to expose the whole image sensor. The peak at 0 nm is the 0th order peak, the little peaks > 1000nm are the second and third order peaks which also make it onto the sensor.

Lessons learned: do the math before making a design.

Back to the drawing board, more later...