Category Archives: optics

Technology used in digital security cameras

Digital security cameras have become one of the most commonly used tools in catching criminals and deterring potential crimes. The cameras keep a constant eye on areas that might otherwise be prime targets for theft, and they’re always on.

Despite their apparent simplicity, there are actually a number of different components used in security cameras to let them do their job. Outside of the basics of a lens, let’s take a look at what makes modern security cameras so useful.

Digital Storage

Storage is the basis of any camera system, but digital cameras rely on digital storage. This is superior to film in a number of ways. It has a much longer lifespan, it can be duplicated easily and inexpensively, and the picture quality is generally better. Some cameras rely on solid-state (SSD) storage that’s stored locally, while others can use a LAN or Internet connection to store footage on a network drive or other remote hard drive. This is the preferred method, as it prevents destruction by an intruder.

Night Vision Technology

Although it’s possibly to put together a pretty serviceable camera without it, night vision technology makes any digital security camera that much better. There are a couple universal components that security cameras can use to achieve night vision.

The most important component of a night vision sensor is an infrared (IR) light sensor. IR light is invisible to the human eye, but cameras with IR sensor can use the spectrum to light up the picture being recorded.

An IR cut filter is also important to producing a good night vision setup. An IR cut filter essentially lets the camera know when to ignore the IR spectrum. Without a cut filter, cameras will produced washed out images that are over saturated during the day. Thus, a cut filter lets the camera produce the best picture it’s technically capable of both during the day and at night.

Motion Triggers

The most advanced cameras have the capability to sense motion and send an alert back to the operator of the camera. This alert can be an audible or visible alert if the camera is being used by a security team, or it can be a text message or phone call for private operators.

There are a few different ways that motion detectors can function. The most common in digital systems is photo-sensitivity. A beam of light is used and focused across a particular part of the area that the camera is being used in. When that beam is broken by an intruder or other object, the change of light is detected and the camera knows to send a trigger. Another common method is to use infrared or photo-analysis. This method looks at changes in the overall image being captured by the camera. It then sends alerts if there is a significant change in what the camera is looking at. The parameters can be adjusted here so that an indoor camera will alert for an intruder, but not for the family dog moving around.

An Internet Connection

For most digital cameras, this is the most obvious need. Using a wired or wireless (Wi-Fi) Internet connection, cameras can be placed online. This allows operators to view the image on the camera remotely, and it also lets the camera send out alerts over the Internet. It also lends a new set of control to the camera – many now have pan, tilt and zoom controls. These let the owner of the camera adjust its field of view remotely, allowing for fewer cameras to be put in place and for better images to be captured.

It’s interesting to see how existing systems work together. Motion detectors, IR light sensors and Internet connectivity aren’t anything new or revolutionary on their own. When brought together, though, they make for one of the most efficient crime-stopping tools that has ever been invented. Digital security cameras are a straightforward idea, but as with all technology, there’s more going on under the hood than meets the eye.

Technology and the Science of Lenses and Optics in Binoculars

The easiest way to describe binoculars as two telescopes, one for each eye, that have been stuck together in one convenient unit. However, this might be not be the most helpful explanation, especially if a person does not know how telescopes work. This article will seek to explain how such a device works in the context of binoculars.

Types of Lenses

A convex lens is a piece of glass that has been curved so that the outside edges are thicker than the middle of the glass. When light hits this piece of glass in its middle, it is forced to slow down and bend. This allows the glass to take objects that are far away and make them appear as though they are closer than they actually are.

A concave lens is a lens that is thicker around the edges and thin in the middle. This causes light, when it enters the lens, to spread out around the edges like how a firework expands. This allows light to cover a larger area when it goes through the lens.

How Telescopes Work

Telescopes are specifically intended to magnify the image of an object that is in the distance. Inside of a telescope’s casing, there are two convex lenses. The first lens takes the light that comes in and captures that image right behind the second lens. It is known as the objective lens because it is focused on the object that is being looked at. The second lens captures the image that is inside of the telescope and makes it bigger.

How Lenses and Prisms Work in Binoculars

Because binoculars are basically two different telescopes that are attached so that they are side by side, there is one for each eye. The main problem with just the two lenses is that the rays, when passing through a lens that is considered to be convex, is that sometimes the images become flipped upside down since the rays are crossing. In order to fix this problem, there are two chunks of glass in each telescope that are put into the binocular.

These wedges are known as prisms that take the image and cause it to flip upside down 180 degrees. The first prism will flip the image by 90 degrees. The second will flip it an additional 90 degrees. These prisms can be located at 90 degree angles from one another, which is known as a Porro formation. They can also be located back to back, which is called the roof prism formation.

Prisms are what makes the binoculars heavy because they are such large wedges. The reason why field lenses are lighter than binoculars is because they only use lenses to flip the image upside down. Because prisms are not used, the image that is produced by field glasses tends to be of a poorer quality.

How do the Numbers Work?

Binoculars tend to have a set of numbers that are separated by an “x” on them.

  • The first of these two numbers describes how many times closer the image will be. If there is a five for the first number, then the image will be five times closer.
  • The second number is the size of the objective lens, which describes the size of the image that is able to be captured.

This brief overview of field glasses provides a basic explanation of the science of binoculars and an introduction to how optics work within binoculars . More information can be found at www.explainthatstuff.com/binoculars.html and http://binocularsreviewhq.com/