The dome cameras are often installed at railway stations and other public areas. A dome camera generally contains a spy camera mounted within a half transparent dome. Generally, these domes are hanged from the ceilings. On a general view they look like a light source. The dome and its inner side is painted black, which makes it more difficult to locate the camera in it. The camera captures by means of a transparent point in the black coating of the dome. Some cameras are fixed within the dome while others can be changed accordingly. Some dome cameras also include a remotely controlled tale lens. This camera is able to monitor close things within a diameter of 10 meters. There are two types of dome cameras: standard size dome camera and compact dome camera. Both these types are used in the railway stations.
The LED lights can give a perfect place for installing a camera. Some banks in Germany use this method in combined observation cameras in their ATM machines. The following information is based on simply closed observation: no ATMs were dismantled and no data was collected from the interior sources. Some German ATMs have a circular plastic conceal above the CRT. Below the conceal, there are three green led’s. The left and right LEDs are opaque while the middle one is clear. The concealed plastic and the LEDs have no definite use. When the three LEDs were analyzed closely, it can be noticed that the left and the right LEDs are absolutely three dimensional objects. The angle of view varies when you look it from different perspectives. Disparately the led in the middle does not appears to be a three dimensional object. Maverick of the direction the led always looks like it is facing the seeker. This shows that there is a fisheye lens installed in the LED. Below the lens there is a two way mirror.
IR pas filters:
Another method of obfuscation of camera lens is the use of infrared pas filters. These types of filters are used to protect the infrared LEDs of the remotely controlled products such as TV or Split AC. These filters appear to be opaque but they allow the IR radiation to pass through them. Since the black and white CCD and CMOS cameras are sensitive to IR radiations, they can capture through the IR filters. As a result these filters give a very productive cover for black and white cameras. Clearly a source for the IR radiation is required for this method. In practical life, this could not be an issue. The light released from the halogen bulbs and even the batteries giving flashlights contain adequate IR radiation for capturing images of good quality.
Experiments revealed that many semi transparent display covers of CD players show features of the same nature as that of an infrared pas filters. Majority of the CD covers allow the infrared radiation to pass through them uninterrupted, but prevent the person from analyzing the inner display of the cover. So cameras located behind these cover are very difficult to find out. The infrared filters can also be integrated on the wall plates. These infrared filter cameras are also used in pubic hotel rooms.
Liquid Crystal Displays:
Many electronic wall clocks operated by batteries contain reflected LC displays. These displays can give an absolute cover for the hidden cameras. The following experiment was carried out with an inexpensive table clock which contains an LC display ranging from 5-3 cm.
The scattered polarizer foil at the back side of the display was replaced by a transparent polarizer foil. A hole of about 2mm was made through the reflecting foil where one of the digits will be displayed later on. To get the pinhole lens closer to the LC display, the board must be put on the external side of the clock. By recreating the board, it would be easy to fix both the lens and the board in the same casing. Active portions of the display cover the hole in the reflective foil surprisingly well. These results the picture captures by the camera dim, but this is negotiable and cannot affect the work anyway. The infrared radiations released by majority of the light sources can pass through the dark portions unaffected. Unless the clock is observed very closely or at viewed sleep viewing angle, the lens is not visible at all.