Spectrograph Integration & Test at LAM

Among the PFS instrument subsystem, four spectrographs are developed under the leadership of LAM (Laboratoire d’Astrophysique de Marseille). Since 2015, the first spectrograph module has been integrated and tested for its performance. In this article, we’ll talk about integration and test activities at LAM.

Below photo shows the Visible-Red camera unit under assembly: optical components were accommodated in the cryostat which had been developed by Johns Hopkins University. Rails and jigs were used to align the optical axis of the mirror, lenses and detector inside the dewar, as shown by this schematic movie.

 (Assembly of Visible-Red camera unit)

We’ve started the performance verification with two kinds of test using the Visible-Red camera unit: thermal validation test and image quality test. Out of the two kinds of test, the image quality one is carried out using “one channel” of the Spectrograph, by delivering the light from the fiber slit through the Visible-Red camera unit, as shown by the below photos. (cf.: See this post for thermal validation test.)Image quality of the spots on the detector, and its stability are supposed to be verified.

 (Configuration of “one channel”)

 (Assembly of “one channel)

This movie shows how the focus position is scanned.

In addition to integration of hardware, dedicated software is also developed to control individual parts sequentially, acquire the data, and analyze them, like the above movie for focus scan. The software not only collects information from environment sensors at various points of the spectrograph, but also control the status of mechanical and electrical parts. Besides, at emergency, an alert message is supposed to be sent to development team via application of smartphones.

(Up: Software developer, Under: GUI for integration & test)

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