LWIR Lenses & Zoom Modules

LWIR Thermal Lenses and Zoom Modules

Fixed lenses from 13 to 85 mm for 640×480 and 1280×1024 arrays with 12 µm pixels, and continuous zoom thermal modules with a built-in 640×480 detector that cover wide angle to telephoto with one lens. Country of origin: Taiwan.

中文

Illustration of an LWIR continuous zoom module with its core housing at the rear, and a fixed thermal lens — Original illustration, not a product photo. Actual appearance varies by model.

Fixed thermal lenses

Optical specifications

Focal length (mm)	F-number	Array	HFOV (°)	Distortion (%)
85	F/1.1	1280×1024	10.4	2
50	F/1.05	1280×1024	17.4	1
35	F/1.1	640×480	12.6	1
25	F/1.1	640×480	17.4	1
19	F/1.0	640×480	23.1	1
18	F/1.0	640×480	23.9	3
13.7	F/1.0	640×480	31	1
13	F/1.0	640×480	33.7	4

Mechanical specifications

Focal length (mm)	Total length (mm)	Weight (g)	Front diameter (mm)	Rear thread	Coating
85	82.75	215	Φ80.5	M34 × P0.5	AR
50	54.55	115	Φ51	M32 × P0.5	AR
35	36.17	29.1	Φ36.5	M25 × P0.5	AR
25	32.3	27.4	Φ28.5	M25 × P0.5	HD (front)
19	27.73	24.9	Φ28.5 (grooved)	M25 × P0.5	AR
18	< 25.8	20	Φ24	M17 × P0.5	AR (front)
13.7	20.39	8.5	Φ19 (knurled)	M16 × P0.5	AR
13	< 23	11	Φ20	M20 × P0.5	HD (front)

Common specifications: 8–12 µm waveband; 12 µm pixel pitch; IP67 at the front; operating temperature −20 to +65 °C, storage −40 to +85 °C. Horizontal fields of view are rated values and include lens distortion; AR means anti-reflection coating.

Continuous zoom thermal modules

Focal length (mm)	F-number	HFOV (wide → tele)	Digital zoom	Frame rate
13–78	F/0.8–1.2	33° → 5.6°	2× / 4× / 8× / 16×	30 / 60 Hz
13–45	F/0.8–1.05	33° → 9.7°	2× / 4× / 8× / 16×	30 / 60 Hz
20–100	F/0.8–1.2	22° → 4.4°	2× / 4× / 8× / 16×	30 / 60 Hz

Common specifications: 640×480 detector, 12 µm pixel pitch; operating temperature −40 to +70 °C.

Choosing a focal length

The horizontal field of view is about 2 × arctan[array width ÷ (2 × focal length)]. A 640×480 array with 12 µm pixels is 7.68 mm wide: 13 mm gives about 33°, 25 mm about 17°, and 78 mm about 5.6°. To work back from target size and distance to a focal length, see our articles on calculating focal length and sizing a payload from GSD. For a full calculation report, see the UAV Payload Specification package.

Fixed lenses: horizontal field of view (rated values including distortion), each fan drawn at its true angle; for the same array, the longer the focal length, the narrower the view. Zoom modules: focal range of the three continuous zoom modules, with the horizontal field of view at the wide and telephoto ends.

Selection calculator

Work out the focal length from target size and distance

Enter the target, the distance and how clearly you need to see it. The calculator works out the focal length you need and shows which lenses and zoom modules on this page can do it.

Detector array (12 µm pixels) 640×480 1280×1024

Critical dimension of the target mFor a person, 0.75 m (as on our UAV payload page)

Distance m

How clearly (Johnson criteria) Detection: something is there (2 pixels) Recognition: tell the class, such as person or animal (8 pixels) Identification: tell details apart (12.8 pixels)

Required ground sample distance (GSD)
Required IFOV
Required focal length

Lens on this page	Focal length	Pixels on target	Level reached	Image width at that distance

Johnson criteria (50 % probability): detection 1 line pair (2 pixels), recognition 4 line pairs (8 pixels), identification 6.4 line pairs (12.8 pixels), the same as on our UAV payload page. GSD = critical dimension ÷ pixels; IFOV = GSD ÷ distance; focal length = pixel pitch ÷ IFOV; image width uses the pinhole model (array width ÷ focal length × distance). This is geometry only: it leaves out atmospheric attenuation, target-to-background temperature difference, lens resolution and thermal crossover, so real ranges are usually shorter, and a combination that only just meets the threshold should not be treated as a sound design. Fixed lenses are listed only for the array they are specified for; the zoom modules include a 640×480 detector.

Send these results with a quote request Commission a full specification study

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Original illustration, not a product photo. Actual appearance varies by model.