Dual three-way infrared beam combiner at the CHARA Array

Two identical three-way beam combiners have been installed at the CHARA Array. The new setup is an extension of the two-beam pupil plain combiner, which has been in use thus far. Using the new beam combiners we can now obtain phase closure data in H, K or J band on two sets of three telescopes. A new optical design has been implemented to image the six outputs of the combiners onto six separate pixels in the infrared detector array. The new optical arrangement provides reduced background and spatial filtering. The magnitude limit of this beam combiner has reached 7.8 in K magnitude mainly as a result of better image quality by the new infrared camera optics.