Long-range IR cameras

	The KDN-10180x from China's Shenzhen Chuangtai has a 65m effective IR range, 16 or 25mm fixed lens, and double glass and hoop design.

Steady global demand growth prompts makers to advance designs with LED arrays, laser diodes and compact housings.

The steady rise in demand for long-distance day and night surveillance products is bolstering China’s long-range infrared camera industry. The line’s increasing acceptance among consumers and the low technology threshold have encouraged about 75 percent of CCTV camera makers in the country to develop and release the device.

There are at present 300 companies engaged in the manufacture of long-range units. The selection includes bullet, dome, speed dome, PTZ and IP-based models.

Optimistic about the segment’s continued growth in coming years, China suppliers are boosting product development to grab a bigger slice of the market. Among the R&D priorities is the use of new technologies to improve performance.

About half of China makers have already launched models that adopt LED array technology, and many others are developing compliant products. The technology boasts high integration capability, high electro-optical efficiency at 2.5 times greater than the conventional IR LED light, an adjustable viewing angle of 10 to 120 degrees and a longer life span.

Some companies, however, believe that cameras adopting this solution will not soon be mainstream due to high cost. An IR LED array module is two to three times more expensive than an IR LED module.

One emerging technology is the use of laser diodes as the light source. Its core advantages are longer effective range at 500m to 2km, and lower power consumption and light divergence. But as the technology is not yet fully developed, compliant models are more expensive and have a shorter life span. Even so, companies such as Changzhou Minking have unveiled long-range IR cameras adopting IR laser technology, and others have declared plans to develop such products.

Another R&D priority is the development of dual-camera models. These integrate a color CCD sensor used during the day and a b/w CCD sensor at night.

Makers are also releasing more PTZ and speed dome versions. Current speed dome units have an effective range of up to 150m, while PTZ types can support more than 300m.

Companies are also enhancing the cosmetic design of products. Compact and smooth styles are trends. Aside from the traditional IR LED, many recent releases come with several external light modules.

The bulk of China’s long-range IR camera production is absorbed by the domestic market, with makers exporting only 30 to 40 percent of output. North America and the EU currently import most overseas shipments, but their weakened economies are driving many suppliers to shift focus to other export destinations and the domestic front.

	From China, Shenzhen Maxvideo's VM-795 comes with 30 built-in IR LEDs with an effective range of 70 to 100m.

IR cameras with an effective distance of 50m or longer are considered long-range. But due to a lack of consensus on what defines a long-range IR unit, some suppliers include products with 40 or even 30m effective distance in this category.

The IR LED remains the primary choice of light source. Its major advantages are low cost and high lighting efficiency. Many suppliers prefer 850nm IR LEDs as most CCD cameras are more sensitive to IR light on such a wavelength.

The effective distance is largely determined by the radiant power and viewing angle of IR LEDs. China companies, however, label products with the diameter of integrated LEDs instead of the actual radiant power and viewing angle for easy reference.

The radiant power is dictated by the LED chip used, and is not necessarily proportional to the dimension of the IR LED. Most IR LED suppliers, however, produce larger models with higher power than smaller units. The popular ones have diameters of 5, 8, 10, 20 and 25mm, and a viewing angle of 15 to 60 degrees. The 5mm-diameter type has a radiant power of 20 to 80mW/sr, while 8 and 10mm versions have 80 to 135mW/sr. The 20 and 25mm models are more than $135mW/sr. A typical long-range IR camera with a 50m effective distance is equipped with 36 to 48 8mm IR LEDs, although some come with just eight 20mm IR LEDs.

Most long-range IR cameras from China are designed for outdoor applications and are therefore water-resistant. IP55 is the basic specification for mainstream models, while some high-end units are IP67-rated. Accessories such as wipers, mounting kits, fans and heaters are optional to buyers.

Compared with traditional IR cameras, long-range versions consume more power and have problems cooling. As such, these products need an extra heat-dissipation mechanism for overheating protection.

The use of an aluminum core PCB is one standard solution. Some models, especially those with an effective distance of 80m or longer, are equipped with an active fan and auto temperature control. A number of companies incorporate semiconductor refrigeration in upscale units.

A long-range IR camera consists basically of an IR light module, camera module, lens, IR cutoff filter, housing and power supply.

For the light source, makers purchase IR LEDs mostly from local providers, while IR LED chips come from Taiwan. The popular providers are Tyntek and Opto Tech.

To lower production costs, some suppliers source just the semiconductor dies from Taiwan makers and manufacture the IR LED in-house. Only a few high-end models adopt IR LEDs from Taiwan and Japan.

Most long-range IR cameras have CCD sensors with a resolution of 420 to 540 TVL. Mainstream models adopt 1/3in CCD sensors, but some high-end versions use 1/2in units. The most popular are Sony’s CCD sensors such as the Super HAD CCD and EXview HAD CCD series. The latter is commonly used in upscale models because of its optimized light efficiency in the near-IR region. The less-expensive CCD sensors from Sharp and A1 PRO are utilized in midrange and low-end models.

Lenses with an aperture of F1.4 or larger are generally adopted for mainstream models. Local companies, including Fujian Forecam and Xiamen Leading, are the major providers of lenses for midrange and low-end cameras. Some upscale units use imported lenses such as those from Avenir of Japan.

Prices are largely dictated by the sensors used, effective range, form factor and resolution. Low-end models in bullet form start at $30. These have a 50m effective range and 420 TVL resolution. Units with a 1/3in color CCD sensor, 480 TVL and 80 to 100m covered distance are considered midrange and go for $50 to $100.

High-end versions top $100 and have a range longer than 100m, auto iris and zoom lens, 480 to 520 TVL and 1/2 or 1/3in CCD sensor.

Although Sony and Sharp recently raised the cost of their CCD sensors, suppliers of long-range IR cameras in China will keep quotes at current levels to remain competitive.

Fixed and PTZ long-range infrared cameras are produced by at least 10 suppliers in Hong Kong. Many models have a 30m minimum effective distance. Most units are suitable for outdoor, indoor and low-light applications. Outdoor versions are often encased in a durable housing with protection against the weather and other environmental hazards.

As there is no standard way to measure IR night vision range, early models of long-range IR cameras from Hong Kong boasted of exaggerated operation distances. In an attempt to produce models with long night vision range at lower cost, some companies used low-quality LEDs. The components, however, burned out easily, giving suppliers a painful lesson. As a result, they have become meticulous in choosing the LEDs to integrate in their IR cameras.

Nowadays, most makers have stopped overemphasizing the IR night vision distance in specifications, as this is achievable only under optimal conditions. It is now often indicated as a range instead of a fixed number.

For maximum IR radiating power, suppliers are filling up the space around lenses with high-output IR LEDs.

To enhance long-range night vision capability, many new models were developed using the latest camera sensors such as those from Sony. The pickup devices usually adopt sensitivity- enhancement technologies not supported in previous sensors and provide clear images under low and zero-light conditions.

There are other technologies, including multisensor and thermal imaging, that can enable longer night vision distance in surveillance cameras, but only a few Hong Kong suppliers are considering adopting these due to the high cost.

Vigital Technology Ltd recently released a long-range IR camera featuring the dual sense technology, which enhances the camera night vision sensitivity without increasing noise. The technology, combined with Sony’s SuperHAD II Low-Lux CCD sensors, enables the camera to achieve 5 percent higher resolution during daytime and 50 percent at night. The company has also developed and patented a roller mechanical design for easy and accurate focusing of the camera.