Abstract: Transmission apparatus for beam expansion are disclosed. A transmission apparatus includes a light source configured to emit an optical signal, a first feature comprising a diffractive element and a reflective element, and a second feature that is substantially aligned with the first feature. The diffractive element is substantially aligned with the light source to receive the optical signal. The second feature includes an inner surface that is partially reflective and partially transmissive. The first feature is located between the light source and the second feature. The diffractive element is configured to diffract the optical signal, the second feature is configured to: (a) reflect a first portion of the diffracted optical signal and (b) transmit a second portion of the diffracted optical signal to a destination balloon; and the second feature is further configured to transmit at least part of the first portion of the diffracted optical signal to the destination balloon.

Abstract: In the context of a balloon network, embodiments described herein may help to maintain an optical communications link between two balloons. For example, an illustrative balloon may include auxiliary photodetectors that are arranged around the photodetector in the balloon's optical receiver system. The balloon may detect intensity differences between the auxiliary photodetectors on opposite sides of an optical receiver, and adjust the positioning in an effort to reduce the intensity difference, and by so doing, better align the optical receiver with the optical transmitter of the transmitting balloon.

Abstract: In the context of a balloon network, embodiments described herein may help to maintain an optical communications link between two balloons. For example, an illustrative balloon may include auxiliary photodetectors that are arranged around the photodetector in the balloon's optical receiver system. The balloon may detect intensity differences between the auxiliary photodetectors on opposite sides of an optical receiver, and adjust the positioning in an effort to reduce the intensity difference, and by so doing, better align the optical receiver with the optical transmitter of the transmitting balloon.

Abstract: In the context of a balloon network, embodiments described herein may help to maintain an optical communications link between two balloons. For example, an illustrative balloon may include auxiliary photodetectors that are arranged around the photodetector in the balloon's optical receiver system. The balloon may detect intensity differences between the auxiliary photodetectors on opposite sides of an optical receiver, and adjust the positioning in an effort to reduce the intensity difference, and by so doing, better align the optical receiver with the optical transmitter of the transmitting balloon.