A meniscus lens has a dome shape and has a first surface facing a lens array and a second surface facing an infrared sensing element. The meniscus lens has a central portion and a peripheral portion. The central portion includes a top point that is an intersection between the optical axis of the meniscus lens and the first surface. The peripheral portion includes an end of the first surface of the meniscus lens. With respect to the central portion of the meniscus lens, an aplanatic point of the first surface is located at the focus of the lens array. With respect to the peripheral portion of the meniscus lens, an aplanatic point of the second surface is located at the focus of the lens array.

A meniscus lens has a dome shape and has a first surface facing a lens array and a second surface facing an infrared sensing element. The meniscus lens has a central portion and a peripheral portion. The central portion includes a top point that is an intersection between the optical axis of the meniscus lens and the first surface. The peripheral portion includes an end of the first surface of the meniscus lens. With respect to the central portion of the meniscus lens, an aplanatic point of the first surface is located at the focus of the lens array. With respect to the peripheral portion of the meniscus lens, an aplanatic point of the second surface is located at the focus of the lens array.

This disclosure relates to measuring ultraviolet (UV) exposure. One example system includes an electronic sensor chip that includes a UV sensor that measures a UV intensity reading, an inertial measurement unit that acquires movement data of the UV sensor, and at least one processor. The system further includes a light pipe that guides light towards the UV sensor and a diffuser that has an angle-dependent transmission function and covers an end of the light pipe. Example operations can be performed by the processor include determining a solar incidence angle between a direction of the sun and a normal direction of the UV sensor, computing an estimation of a maximum UV intensity at normal incidence based on the UV intensity reading, the solar incidence angle, and the angle-dependent transmission function of the diffuser, and outputting a UV index based on the estimation of the maximum UV intensity at normal incidence.

A sunlight lens portion includes a low elevation angle surface for capturing light at low elevation angles, an opposing surface which is adjacent to the low elevation angle surface and which faces a sunlight detection element, and a high elevation angle surface for capturing light at high elevation angles. Further, the sunlight lens portion includes a reflection surface adjacent to the high elevation angle surface and the opposing surface. Accordingly, a portion of sunlight entering the sunlight lens portion is reflected by the reflection surface and guided to the sunlight detection element, therefore it is possible to broaden a range of peak sunlight amount detected by the sunlight detection element. Due to this, it is possible to reduce an effect of the angle of inclination of the windshield on the elevation angle characteristic of the sunlight sensor.

A sunlight lens portion includes a low elevation angle surface for capturing light at low elevation angles, an opposing surface which is adjacent to the low elevation angle surface and which faces a sunlight detection element, and a high elevation angle surface for capturing light at high elevation angles. Further, the sunlight lens portion includes a reflection surface adjacent to the high elevation angle surface and the opposing surface. Accordingly, a portion of sunlight entering the sunlight lens portion is reflected by the reflection surface and guided to the sunlight detection element, therefore it is possible to broaden a range of peak sunlight amount detected by the sunlight detection element. Due to this, it is possible to reduce an effect of the angle of inclination of the windshield on the elevation angle characteristic of the sunlight sensor.