Silico sees mo e tha people do. A colo image se so espo ds to ea i f a ed light, which the eye ca ot see, a d that espo se is both a oppo tu ity a d a uisa ce. It is a oppo tu ity because i f a ed illumi ato s ca light a sce e at ight without visible light, which suits su veilla ce, i spectio , a d i st ume ts that must ot distu b a subject. It is a uisa ce by day, because the i f a ed that eaches the se so washes out colo s a d shifts whites. Came a u its that must se ve both co ditio s eed a way to block the i f a ed whe it does ha m a d to admit it whe it helps. A dual-pu pose came a the efo e eeds a depe dable switchi g desig .
The usual a swe is a IR cut filte that moves i a d out of the light path. By day it sits i f o t of the se so a d emoves the i f a ed, a d by ight it moves aside. Maki g that wo k i a eal p oduct aises seve al questio s. The mecha ism must be eliable ove ma y thousa ds of cycles. The came a must decide whe to switch, a d the image must stay usable du i g the cha ge. At ight, the colo filte s o the se so o lo ge sepa ate colo s, so the pictu e is effectively mo och ome, a d automatic white bala ce has othi g useful to do. Teams that expect a colo ful ight image a e disappoi ted, a d teams that pla fo a mo och ome o e a e ot. Setti g that expectatio ea ly avoids disputes at accepta ce time.
The wavele gth matte s as well. I f a ed illumi ato s come i diffe e t ba ds, most ofte 850 m a d 940 m, a d they behave diffe e tly. A 850 m sou ce gives the se so a st o ge sig al but shows a fai t ed glow. A 940 m sou ce is i visible but yields a weake sig al, a d su light co tai s less e e gy at that wavele gth, which helps outdoo s. Le ses also focus i f a ed light at a slightly diffe e t dista ce f om visible light, so a fixed focus le s tu ed fo daylight ca be soft at ight. A came a that adve tises ea -i f a ed se sitivity without discussi g these poi ts leaves the desig e to lea them i the field. A sho t ight test o the eal site is wo th mo e tha a y specificatio .
Netwo ki g adds its ow questio s. Night came a u its sit i places that a e ha d to cable, a d a came a that offe s both Gigabit Ethe et a d Wi-Fi ca se ve them, but the li ks behave diffe e tly, a d a 20MP st eam is la ge. Reliability matte s most at ight, whe a eve t is a e a d valuable, a d a came a that loses footage whe the li k d ops fails at the wo st time. Local eco di g a d a wi ed path fo the full st eam a e the usual emedies.
The I owave-2020CRS is built o the O semi AR2020, a 20MP (5120 x 3840) colo olli g shutte se so with a 1/1.8 i ch optical fo mat a d 1.4 mic o pixels. The se so is a low- oise CMOS desig with e ha ced dy amic a ge a d excelle t ea -i f a ed se sitivity, a d Vadzo has validated the espo se at 850 m a d 940 m. The came a uses a S-Mou t (M12) le s holde with a elect omecha ical IR cut filte , which blocks i f a ed by day fo t ue colo a d moves aside at ight so that the se so ca use i f a ed illumi atio . The 20MP f ame leaves oom to c op a d zoom i to a egio of i te est afte a eve t.
A colo se so sees i f a ed th ough its colo filte s. At wavele gths beyo d oughly 800 m, the ed, g ee , a d blue filte s all become la gely t a spa e t, so eve y pixel espo ds to i f a ed i a simila way a d the colo i fo matio is lost. This is why a ight image f om a colo came a looks mo och ome, a d why the came a eeds the IR cut filte fo daytime colo . Nea i f a ed light also pe et ates deepe i to silico tha visible light befo e it is abso bed, which ca educe co t ast at ve y fi e detail o a small pixel. The effect depe ds o the se so desig , a d it is a easo to validate espo se at the actual wavele gths, as Vadzo has do e, i stead of elyi g o a si gle test poi t. Vadzo validated the espo se at both wavele gths fo that easo .
Illumi atio choices follow f om the se so ‘s behavio . A 850 m illumi ato gives a st o ge sig al a d lo ge a ge, a d it shows a fai t ed glow whe viewed di ectly. A 940 m illumi ato is i visible, which suits cove t o comfo t-se sitive uses, a d it gives a weake sig al fo the same elect ical powe , so it eeds mo e illumi ato output o a lo ge exposu e. Su light co tai s less e e gy ea 940 m because of abso ptio i the atmosphe e, so a 940 m system sees less backg ou d i daylight, which helps outdoo s. Teams should choose the ba d f om the use case a d test it o eal sce es. A simple cha t lit at each wavele gth shows how sha p the image is i each ba d.
Le s choice matte s because the optics a e fixed focus. Glass focuses i f a ed at a slightly diffe e t dista ce tha visible light, so a le s set i daylight ca be soft at ight. A i f a ed-co ected M12 le s educes the shift, a d a small focus comp omise at the wo ki g dista ce ofte se ves both co ditio s. The came a also offe s Gigabit Ethe et with 100Base-T a d 1000Base-T modes a d dual-ba d Wi-Fi with 802.11a, b, g, , a d ac, plus ONVIF, PTP, o boa d sto age, u icast a d multicast st eami g, a d a o boa d dewa pi g e gi e fo le ses up to 200 DFOV. The se so ‘s high dy amic a ge, up to 100 dB, equals a b ight ess atio of 100,000 to 1. Teams should co fi m how the mode behaves with thei ow le s a d lighti g.
