8/7/2023 0 Comments Diffraction limit calculator![]() In general, one should consider using a lens that has a higher optical resolution than the camera pixel-size limited resolution. The highest spatial frequency which can be resolved by a sensor, the Nyquist frequency, is effectively two pixels or one line pair. One can therefore arrive at a simple formula to estimate the camera-pixel-size limited spatial resolution of a camera:Ĭamera pixel size limited resolution (in lp/mm) = 1000/(2 x pixel-size-in-μm) = 500/(pixel-size-in-μm).įor example, a camera that is based on Sony CMOS Pregius Gen2 imagers such as the IMX264 or IMX304 with a pixel size of 3.45μm has the capability of resolving 500/3.45 = 145 lp/mm. Per Nyquist, it takes a minimum of two pixels to resolve a feature in an image. The limiting resolution of a camera with 100μm pixels As shown above, if the pixel size is considerably larger than 100μm, the alternating black and white pattern may be imaged into a blurred gray image. If the pixel size was greater than 100μm, information about the black and white lines would be not be sampled properly. How does the pixel size of the camera impact the Optical Resolution of the System? The limiting pixel-size for sampling these lines effectively with camera pixels is 100μm, as shown. This translates to an optical resolution limit of 10 μm for the system, unless limited by something else (e.g. If a lens is said to be able to resolve 100 lines per millimeter, it means that the lens can resolve up to 100 equally-sized lines that are small enough to fit within a space of 1mm for this, each line must be 0.01mm wide. Permitting a slightly lower resolution towards the edge allows the lens manufacturer to produce more cost-effective lenses. This constrains the lens manufacturer to ensure a higher optical quality in the center of the imaging area which tends to be more important to users. For example, lenses in the 1-1955x series are specified to have Center | Edge resolutions of 100 | 160 lp/mm respectively. Note also that the optical resolution of the lens in lp/mm may be specified with two different numbers representing the optical resolution at the Central | Peripheral regions of the lens. Each line pair = 1mm/5 = 1000μm/5 = 200μmĪ line pair: 1 black line + 1 white line, each 100μm ![]() ![]() 5 line-pairs per mm, comprised of 10 equally spaced lines, of which 5 are black and 5 are white. It is normally specified in line pairs per millimeter and it is a function of the optical quality of the lens, including the lens design (including the manufacturing tolerances) and the materials, which contribute to the overall Optical Resolution of the lens. Lens manufacturers typically provide this number as a specification of the optical quality of the lens. How is Optical Resolution of a Lens specified? ![]() Because of this, the Optical Resolution of the overall system may be said to be camera-limited or lens-limited.Īlthough this is not always true, cameras tend to be more expensive than lenses – therefore, the goal of most system designers is to select a camera first based on the “photonics” requirements, and then select a lens with an Optical Resolution that is better than or equal to the Optical Resolution of the camera. The lower of the two typically sets the Optical Resolution of the system. For the sake of simplicity, the topic of the Optical Resolution in this article is discussed independent of contrast, with the topic of Modulation Transfer Function (MTF) covered in a separate article.Ĭameras and lenses contribute in different ways to the overall Optical Resolution of a Camera + Lens system. Resolution is tied to contrast – the ability of the system to discern shades of gray. Optical Resolution is defined as the smallest sized feature that a given optical system is able to resolve. ![]() Previous Article Back to Topics Next Article ![]()
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