Posts Tagged ‘ CMOSs ’

Camera Night Vision Helmet Mount

Thursday, October 14th, 2010

Talk about stretching the limits of technology, try a camera night vision helmet mount. These cameras may be custom created using a specific helmet, mount, camera, Digital Video Recorder or DVR, and battery pack, or may be purchased as one system or unit. The cameras are small and light enough in weight to be mounted to a helmet with other components attached on the user or the user’s clothing or gear.

There are many uses for a camera night vision helmet mount. One of the most popular uses for this type of surveillance camera is as a tactical device used by various military personnel on a variety of assignments. The news and sports media may also use this camera for Point Of View or POV camera shots, especially for fast paced, extreme non-contact types of sports (skateboarding or snow skiing for example). These cameras also are used by home inspectors, contractors, pest control applicators, mine inspectors, and just about anyone that needs to use a hands-free device to record or document video in low or no light conditions.

There are just about as many camera night vision helmet mount systems commercially available as there are uses. The cameras can vary in size, shape, and features, but there are some night vision cameras that can be mounted on a helmet that are as small as a U.S. quarter. Usually these cameras have their own built-in lighting for infrared operation and this is what becomes the limiting factor in the size of the camera.

Regardless of the size or type, camera night vision helmet mount systems share some basic characteristics and/or features. The following paragraphs will describe how these systems work and some of the common features.

Just like their full size, stationary mounted security camera cousins, camera night vision helmet mounts are digital video cameras. They work by transferring radiation in the form of visible or near infrared spectrum light into electrical impulses that can be used to create a digital image. They do this by using an electronic sensor chip.

There are two different types of sensor chips, Charged Coupled Devices or CCDs and Complimentary Metal Oxide Semiconductors or CMOSs. Each is also inherently sensitive to near infrared spectrum light; light or radiation that is invisible to the human eye. For infrared operation, infrared Light Emitting Diodes or LEDs are used to illuminate the field of view or target.

The more LEDs used for infrared lighting the greater the range in distance for infrared capture. However, as mentioned above, the LEDs not only become a factor in camera size but also in electrical power consumption. There are camera night vision helmet mount systems that have up to 9 LEDs or more, operate off of 5 volts DC, with only a 50 mA drain, and yield a maximum effective infrared range of from 80 to 100 feet.

Digital video cameras create video by taking several digital photographs in rapid succession. To the human eye fluid motion is obtained by taking about 30 photographs, called frames, per second or 30 FPS. Each one of these frames has the digital data equivalent to a single digital photograph and is contained within a digital video file that is normally stored on a DVR.

Although DVRs in standard security systems usually consist of a hard disk drive like the one found in a Personal Computer (PC), camera night vision helmet mount systems usually use SD cards or other similar small, portable memory media including Flash drives. In addition, helmet camera systems’ DVRs may or may not include a built in monitor.

The monitor on a camera night vision helmet mount is usually a small TFT-LCD (Thin Film Transistor Liquid Crystal Display) that ranges in size from about one to four inches. Usually, the DVR including the memory media port and the monitor are built as one unit and may often be mounted or carried separately from the camera. Often these are clipped to a belt, held in clothing pockets, or are attached to guns and other tactical devices.

All camera night vision helmet mount systems require electrical power to operate. This may be provided in the form of one-time use batteries, rechargeable batteries, or battery packs. The batteries or the battery pack may be incorporated in the body of the camera or the DVR or may occur as a separate component.

As technology increases, camera night vision helmet mounted systems get smaller, use less power longer, and increase their potential for high quality video.


Autofocus CCTV Camera

Tuesday, July 27th, 2010

An autofocus CCTV or Closed Circuit Television camera is an ideal choice for surveillance and monitoring when the field of view encompasses large differences in distances of the target or the target is moving and often changes its distance to the camera. Most autofocus CCTV camera lenses are zoom lenses; a variation of this type of lens is a vari-focal lens which can vary its focal length by manual adjustment.

Let’s take a look at some of the technology behind autofocus CCTV cameras to see how they work and to understand why an autofocus CCTV camera is unique.

A typical digital video CCTV camera produces an electronic image by using one of two light sensitive electronic chips called Charged Coupled Devices or CCDs or Complimentary Metal Oxide Semiconductors or CMOSs. The sensors create electronic energy from light energy and are often only ¼ to 1 inch in size. The electronic energy can be measured and utilized to make digital video images that can be viewed on a monitor or saved on a storage device.

However, in order for the sensor to produce the electronic image, the light emitted from the actual imaged must be precisely focused on the sensor. This is where the lens comes in to play. The lens works by clarifying and concentrating (focusing) the light image on the sensor chip.

Every lens has a focal length. For CCTV cameras, generally short focal length lenses have wide fields of view which are ideal for close ups or for seeing a large area, although objects will appear relatively small. Long focal length lenses have narrow fields of view but distant targets are easier seen with better definition.

Focal length measurements are not very long. In fact, focal lengths for CCTV cameras are measured in millimeters and range from about 3.5 to 16.0 millimeters in length with each lens having its own unique focal length. When purchasing a digital video CCTV camera with a fixed lens, the purpose or objective of the camera must be considered in order to select the proper lens.

For example, a small focal lengths lens can yield a fairly large field of view. For example, at 50 feet away from the camera, the field of view for a 3.6 mm focal length lens would provide a field of view of approximately 75 feet wide and 50 feet in height. Identification of people would be very difficult because they would appear very small. However, using a lens with a 16.0 mm focal length would create a field of view approximately 13 feet wide by 9.6 feet in height and would make recognition much easier.

However, if a camera needs to provide both a large field of view as well as a short field of view, an autofocus CCTV camera is the ideal choice. By using a combination of lenses that optimize the physical principles of the lenses these cameras can vary their focal length automatically, i.e. autofocus.

Autofocus CCTV cameras take the guess work out of determining which single lens to purchase for your camera. Autofocus zoom CCTV cameras can be used like the telephoto lens on a still image or video camera to “Zoom-in” or enlarge objects while maintaining the proper focus. Autofocus zoom CCTV cameras often have large focal length ranges, from as little as 3.6 mm to over 60 mm.

Autofocus CCTV cameras can be zoomed in or out to account for changes in the field of view. Normally, these cameras’ zoom function is controlled electronically either by a control panel with sliders, levers, knobs, joysticks, or buttons or through the use of programming that is run through the processing unit or Digital Video Recorder (DVR).

Another type of “autofocus” camera lens is the vari-focal lens. Although this lens is not remotely controlled like the true autofocus lens mentioned above, it does have the ability to vary its focal length, making it an autofocus type of lens. The lens is actually adjusted manually allowing the lens to zoom in and out and focus at variable settings.

So if your security or monitoring system requires the camera to zoom in and out, or if you need to vary the size of your camera’s field of view, an autofocus CCTV camera is the right choice for you. Also, for situations where the filed of view may need to change occasionally but not “on-the-fly” a more economical type of autofocus CCTV lens, the vari-focal lens, may be what you need.