The aperture in a MEMS system is constrained by the size of the mirror which is used to scan the laser beam. In comparison, multi-beam flash lidar have apertures anywhere from 2 to 10x greater in diameter and 4 to 100x greater in area and similarly increased sensitivity to obscurants. Micro-Electro-Mechanical Systems (MEMS lidar) have a significant disadvantage with small apertures of only 1-4 mm in diameter for oscillating mirror modules. Particles can easily block the small apertures of MEMS scanners To measure intensity degradation over range, we moved the lidar sensor farther from the target and repeated this process at various distances. These two values were compared to determine the impact on signal intensity. Then, we placed “bugs” measuring 5 mm in diameter on the sensor window facing the target board, and measured the new intensity values. To benchmark performance, we gathered intensity values, or return strength of the laser pulse, with a clean sensor window. Our setup consisted of an OS1-64 lidar sensor and a calibrated 10% reflective lambertian target. We conducted a series of tests to demonstrate how the large aperture of the OS1 is minimally impacted by even relatively large window obscurants, like a large insect. That is all to say, a small optical aperture poses an issue for any camera or lidar operating in an environment where dust, rain, mud, snow and other obscurants are to be expected. Small apertures are more susceptible to obscurants blocking all light ![]() On the other hand, if the aperture is larger than the obscurant, light is only partially attenuated and the image will show partial impact. If an opaque obscurant (like dirt or a bug) is larger than the aperture, it will completely block it and blind the camera. The aperture size also affects the impact obscurants have on the image sensor. This is called the “front lens aperture” – or “entrance pupil” in optics design circles – and for the purposes of this article, aperture refers to the front lens aperture and not the mechanical aperture buried inside the lens. The aperture is typically located deep inside the lens, but opening and closing it will also affect the size of the light collecting area on the front lens surface. ![]() In cameras, aperture refers to the opening that controls light coming in to the lens system and the image sensor. The OS1, fresh from a shower with refractive beam obscurants (aka water droplets) What is Optical Aperture and Why is it Important?Ĭamera lenses are a simplified version of our lidar lenses, so let’s consider the camera case first, to gain some intuition.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |