Spot centroid sensitivity to angle of intensity on image detector with lenslet array.

Lenslet array was introduced to an image detector to compensate for low sensitivity. These lenses deviate the light from different incident angles and potentially introduce errors when subpixel accuracy is needed. We investigated the spot centroid position because the angle of incidence changes on a Kodak KAI-16000 image detector with lenslet array. In our experiment, we noticed that there is a cubic dependency on the incident angle. The experimental results show that dependence on the angle of incidence is related to the lenslet array in the Kodak detector used for the pentaprism test. This situation caused an error in spherical aberration on the test surface after integration. The magnitude of the cubic component at incident angle of 14° (equivalent to F/2) is 11.6 µm, which corresponds to a 48 nm rms spherical aberration for the test surface and brings the scanning pentaprism test closer to the principal test while there is a 56 nm rms discrepancy. The discrepancy in spherical aberration between the two tests reduced to 8 nm after this calibration. It also showed the contrast measurement results for the Kodak detector and PointGrey detector. We performed experiments with two different detectors to quantify this effect.