How does F22 achieve lock if it's missiles are hidden in its bay?

The AIM-9X seeks and homes in on IR energy emitted by the target. When an IR-emitting source enters the seeker field of view, an audio signal is generated by the electronics unit. The pilot hears the signal through the headset, indicating that the AIM-9X has acquired a potential target. One method of cueing the AIM-9X to the target’s IR energy source is referred to as boresight, whereby the missile is physically pointed toward the target via the pilot maneuvering the aircraft. The IR energy gathered by the missile seeker is converted to electronic signals that enable the missile to acquire and track the target up to its seeker gimbal limits. A second method of cueing the AIM-9X to the target’s IR energy is the Sidewinder Expanded Acquisition Mode (SEAM). SEAM slaves the AIM-9X seeker to the aircraft radar. The aircraft avionics system can slave the missile seeker up to a given number of degrees from the missile/aircraft boresight axis. The missile seeker is slaved until an audible signal indicates seeker target acquisition. Upon target acquisition, a seeker interlock in the missile is released (uncaged) and the missile seeker begins tracking the target. The AIM-9X seeker will then continue to track the target. A third method for cueing the AIM-9X to the target’s IR energy is through use of the JHMCS. This method allows the pilot to cue the AIM-9X seeker to high off-boresight targets via helmet movement. The pilot can launch the AIM-9X anytime after receipt of the appropriate audible signal.