Page Comparison

Safety Function

Light Path

Hazard

Focused sunlight along optical path

Triggering Event

Any of the following:

• TEOA safety function activated

• Safety shutter not fully stowed

• Telescope Altitude permissive removed

• Telescope Azimuth permissive removed

• M1 Cover UPS failure

• Aperture cover drive ‘not ready’

• Separation angle between Sun and optical path > 1.5R_☉

• Heat Stop fuse wire not OK

• Instrument Field-of-view misconfigured

Priority

The Light Path shall take priority over all other control functions.

Modes

When light path is not blocked

• Sun above horizon and

• Enclosure Aperture pointing within 25° of the Sun

Reaction

Block light path using sequence:

Close M1 Cover then

Close Aperture Cover

Safe State

Aperture Cover closed

M1 Mirror Cover closed

Required Integrity

SIL2