Pixels come in various sizes depending on what is required for the application. A large pixel size is optimal for low light imaging conditions that are less concerned with high resolution. In comparison, a smaller pixel size is optimal for bright imaging conditions in which resolving fine detail is of the utmost importance.

For example, if you are trying to measure a few bright spots that are α nm apart, you will need to measure at least every nm to capture the spatial frequency (i.e. resolve the bright spots). This spatial frequency allows the gaps between the bright spots to be captured as a black pixel (i.e. a pixel without signal). If the distance between the bright spots is less than the size of the pixel, a black pixel will not be captured and therefore the bright spots will not be resolved. This is why smaller pixels provide higher resolution, as shown in Figure 2.

Pixelink

Camera resolution is determined by the pixel size, lens aperture, magnification and Nyquist limit. Overcoming the Nyquist limit is down to the pixel size, with smaller pixels allowing for even smaller details to be resolved. This is because the distance between two neighboring objects needs to be bigger than that of one pixel size, allowing for a black pixel to be captured distinguishing a gap between the two objects.

Both pixel size and lens aperture diameter need to be taken into consideration when choosing the right camera for a research application.

Figure 2: Schematic showing that there needs to be at lest one pixel width between two objects for the Nyquist limit to be overcome, allowing the two objects to be resolved. This is why smaller pixels provide higher resolution as they are able to distinguish between smaller objects.

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Many of us wear our glasses every day; we wear them throughout our workday, when we’re out on a walk, when we’re driving, and when we’re reading in bed. As unique individuals with unique schedules, hobbies, and duties, it doesn’t make sense for everyone to have the same functional lenses in their glasses. Personalizing your lens coatings in order to tailor your glasses to your specific needs will not only prolong the life of your glasses but will also ensure that your glasses serve you to the best of their ability. At Hakim Optical, we have an array of unique and accommodating lenses for your specific needs!

A pixel is the part of a sensor which collects photons so they can be converted into photoelectrons. Multiple pixels cover the surface of the sensor so that both the number of photons detected, and the location of these photons can be determined.

Camera resolution is the ability of the imaging device to resolve two point that are close together. The higher the resolution, the smaller the detail that can be resolved from an object. It is influenced by pixel size, magnification, camera optics and the Nyquist limit. Camera resolution can be determined by the equation:

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Special Optics

Figure 3: (A) Depiction of a diffraction pattern produced when a light source passes througha lens aperture. (B) An example of an Airy pattern determined by light diffracted throughan aperture. (C) Top: Two neighboring Airy patterns that can be distinguished from each otherdue to the separation of the Airy disks. Middle: Two merging Airy disks, preventing them from being distinguished. Bottom: Two neighboring Airy patterns fully merged.

Two different points on an object being imaged produce two different Airy patterns. If the angular separation between the two points is greater than the angular radius of their Airy disk, the two objects can be resolved (Rayleigh's Criterion). If the angular separation is smaller, however, the two distinct points on the object merge. This can be seen in Figure 3C.

It is also important to consider the resolution of the camera lens when determining the overall system resolution. The ability for a lens to resolve an object is limited by diffraction. When the light emitted from an object travels through a lens aperture it diffracts, forming a diffraction pattern in the image (as shown in Figure 3A). This is known as an Airy pattern, and has a central spot surrounded by bright rings with darker regions in-between (Figure 3B). The central bright spot is called an Airy disk, of which the angular radius is given by:

The function of lens coatings is described quite literally in its name! A lens coating is a finishing coat that works with your lenses to enhance their ability to help you see, or to accomplish daily tasks. A lens coating may take the form of an anti-reflection, a water-resistant finish, or even a scratch-resistant surface. At Hakim Optical, we believe anyone can find a coating that will benefit their needs and lifestyle.

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Nyquist limit determines whether a sensor can differentiate between two neighboring objects. If the distance between two objects is greater than the Nyquist limit, or exceed this limit by a factor of at least 2, a sensor can distinguish between the two objects. The Nyquist limit is determined by the spatial frequency (number of bright spots within a given distance) of the object you are trying to image.

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The angular radius of the Airy disk is determined by the aperture of the lens; therefore, the diameter of the lens aperture also determines resolution. As the diameter of the lens aperture and the angular radius of the Airy disk have an inverse relationship, the larger the aperture the smaller the angular radius. This means that a larger aperture results in higher lens resolution as the distance between smaller details can remain greater than the angular radius of the Airy disk. This is often why astronomical telescopes have large lens diameters to be able to resolve the finer details in stars.

Where 2.3 compensates for the Nyquist limit. This limit is determined by the Rayleigh Criterion of the sample. The Rayleigh Criterion is defined by whether or not two neighboring Airy disks (central bright spot of the diffraction pattern from a light source) can be distinguished from one another, determining the smallest point that can be resolved (as shown in Figure 1).

Smaller pixels are able to provide higher spatial resolution but capture less photons per pixel. To try and overcome this, sensors can be back-illuminated to maximize the amount of light being captured and converted by each pixel.

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Pixels come in many different sizes, each having their advantages and disadvantages. Larger pixels are able to collect more photons, due to their increase in surface area. This allows more photons to be converted into photoelectrons, increasing the sensitivity of the sensor. However, this is at the cost of resolution.

USBcamera

The size of the pixel also determines the overall size of the sensor. For example, a sensor which has 1024 x 1024 pixels, each with a 169 μm2 surface area, results in a sensor size of 13.3 x 13.3 mm. Yet, a sensor with the same number of pixels, now with a 42.25 μm2 surface area, results in a sensor size of 6.7 x 6.7 mm.

If you live in an area with lots of rainy weather you might want to consider getting an oil or water-repellent lens coating! Water, thumb smudges, and other debris that may touch your face throughout the day will not stick to your glasses and impair your vision when you have oil and water-repellent lenses.

Lens resolution is limited by diffraction. Airy patterns are formed when light from an object diffracts through a lens aperture. These Airy patterns have bright central spots called Airy disks, which have an angular radius determined by the lens aperture diameter. Two neighboring objects can be resolved if the angular separation between the objects is greater than the angular radius of the Airy disk. As this is inversely related to the aperture diameter, a larger lens aperture results in higher resolution.

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If you work with your hands you should consider trying a pair of anti-static lenses! Whether you craft, woodwork, sew, or hike, anti-static lenses will keep any debris from the air or from your activities off of your glasses to make sure you can see (and work) your best!

The size of the pixel also determines the number of pixels on a sensor, with a fixed sensor size having more pixels on the surface with smaller pixel surface area.

Figure 1: Left: Two neighboring Airy disks that can be distinguished from each other. Right: Two nieghboring Airy disks that cannotbe distinguished from each other as they are below the Rayleigh Criterion.