The Optris CTi LT is a two-piece infrared thermometer for precise non-contact temperature measurement from –58 °F to 1,922 °F (–50 °C to 1,050 °C) in the 8–14 µm spectral range. Optris describes it as one of the smallest infrared sensors worldwide, with up to 22:1 optical resolution. Its rugged 0.55 in (14 mm) sensing head is usable up to 356 °F (180 °C) ambient without cooling, and the heads are vacuum-compatible. The head connects by cable to an electronics box with programming keys, a backlit LCD display, and a built-in USB interface for setup via mobile phone or PC.
Temperature range: –58 °F to 1,922 °F (–50 °C to 1,050 °C) across three models
Smallest spot: 0.02 in at 0.4 in (0.6 mm at 10 mm), LT22 with CF lens
Measurement uncertainty: ± 1% or ± 1.8 °F (± 1 °C), whichever is greater
NETD: down to 25 mK (typical)
Response time: 40 ms (LT02); 115 ms (LT15 and LT22)
Sensing head: 0.55 in (14 mm) diameter × 1.10 in (28 mm) length; up to 356 °F (180 °C) ambient without cooling (LT02: 248 °F / 120 °C)
Environmental rating: IP65 (NEMA-4)
Outputs: two analog outputs (0/4–20 mA, 0–5/10 V, thermocouple K, alarm); built-in USB
Power supply: 8–30 V DC / 1.2 W
At a glance
–58 °F to 1,922 °F (–50 °C to 1,050 °C) across three models
8–14 µm spectral range for low-temperature and general surfaces
0.55"/14 mm sensing head runs to 356 °F (180 °C) without cooling
Up to 22:1 optics with spots from 0.02"/0.6 mm using the CF lens
Sensing head
14 mm, to 180 °C
A 0.55 in (14 mm) head with an M12 × 1 thread, usable to 356 °F (180 °C) ambient with no cooling, and vacuum-compatible.
Resolution
25 mK NETD
Noise-equivalent temperature difference down to 25 mK, with repeatability to ± 0.18 °F (± 0.1 °C) on the LT15.
Optics
Up to 22:1
Standard focus, close focus, or an additional CF lens taking spot size down to 0.02 in (0.6 mm) on the LT22.
What it is used for
Some of the use cases for the Optris CTi LT include:
Low-temperature measurement: non-contact measurement from –58 °F (–50 °C).
General process temperature monitoring: measurement up to 1,922 °F (1,050 °C) in the 8–14 µm range.
Hot installation locations: mounting the sensing head in ambient temperatures up to 356 °F (180 °C) without cooling.
Small targets: spots down to 0.02 in (0.6 mm) with the LT22 and the CF lens.
Vacuum applications: the CTi LT pyrometer heads are vacuum-compatible.
Tight installations: fitting the 0.55 in (14 mm) head into confined locations, with the electronics box sited remotely.
The model range
Temperature ranges are scalable via the programming keys or software and app. Full optical, electrical, and environmental data is in the Specifications tab.
Model comparison
Model
Temperature range
Optical resolution
Repeatability
NETD (typical)
Response time
LT02
–58 °F to 1,202 °F (–50 °C to 650 °C)
2:1
± 0.36 °F (± 0.2 °C) or ± 0.1%
25 mK
40 ms
LT15
–58 °F to 1,472 °F (–50 °C to 800 °C)
15:1
± 0.18 °F (± 0.1 °C) or ± 0.1%
25 mK
115 ms
LT22
–58 °F to 1,922 °F (–50 °C to 1,050 °C)
22:1
± 0.27 °F (± 0.15 °C) or ± 0.1%
35 mK
115 ms
Key features
Very small sensing head: described by Optris as one of the smallest infrared sensors worldwide, with up to 22:1 optical resolution.
Rugged, high-temperature head: usable up to 356 °F (180 °C) ambient without cooling, and vacuum-compatible.
Low noise: NETD down to 25 mK.
Optics options: standard focus, close focus (CF) optics, or an additional CF lens (ACCTCF) for spots down to 0.02 in (0.6 mm).
Two-piece design: separate sensing head and electronics box with easily accessible programming keys and a backlit LCD display.
Built-in USB interface: simple sensor setup via mobile phone or PC.
Selectable analog outputs: two outputs, each 0/4–20 mA, 0–5 V, 0–10 V, or thermocouple type K, plus an alarm output.
Optional fieldbus interfaces: EtherNet/IP, Profinet, EtherCAT, Ethernet TCP/IP with Modbus TCP, Modbus RTU, RS485, RS232, or two optically isolated relay outputs.
Three programmable I/O pins: external emissivity adjustment, ambient temperature compensation, uncommitted value, trigger (reset of hold functions), or alarm output.
Signal processing: peak hold, valley hold, and averaging, plus extended hold functions with threshold and hysteresis.
Easy sensing head exchange: heads can be exchanged within a model group by entering the head's calibration code into the electronics box.
Software and app: configuration through Optris CompactPlus Connect software or the IRmobile app.
Why engineers pick it
Small head, high ambient. A 0.55 in (14 mm) head that runs at up to 356 °F (180 °C) without cooling, and works in vacuum.
Wide range. –58 °F to 1,922 °F (–50 °C to 1,050 °C) across three models, with ± 1% or ± 1.8 °F (± 1 °C) uncertainty.
Simple setup. Programming keys, a backlit LCD display, and USB setup via phone or PC.
Flexible integration. Two analog outputs, three programmable I/O pins, and optional industrial Ethernet, fieldbus, and relay interfaces.
Frequently asked questions
Can I use the CTi LT as a 2-wire sensor?
No. Do not connect a supply voltage to the analog outputs, as this will destroy the output. The CTi LT is not a 2-wire sensor. If you need a two-wire device, review the Optris CSmicro series instead.
What distance-to-spot size ratio is correct for my application?
The size of the measuring object and the thermometer's optical resolution determine the maximum distance between the sensing head and the object. To prevent measuring errors, the object should fill the field of view of the optics. The spot should always be the same size as the object or smaller.
Which settings change if an external close-focus lens is used?
The optional CF lens allows measurement of small objects. When it is fitted, transmission must be set to 0.78. That figure is an average characteristic value and may scatter between units, so determine it experimentally if your application requires it.
Can I shorten the cable between the sensing head and the electronics box?
It is not recommended, because the cable's impedance forms part of the sensor calibration. On all CTi LT models the sensing head cable can be shortened if necessary, but doing so introduces an additional measuring error of about 0.1 K per metre removed.
How do I exchange the sensing head?
Heads are connected and calibrated at the factory. Any exchange of sensing heads and electronics is possible within a given model group. Every head carries a specific calibration code printed on the head cable, and that code must be stored in the electronics box for correct temperature measurement and sensor functionality.
How can I improve the noise amplitude of the sensor?
Do not move the head cable during measurement. Use shielded cables only and ground the sensor shield. Avoid ground loops and related signal interference in industrial environments. It may be necessary to interrupt the ground connections inside the electronics box by switching the internal jumper to another position. Review the manual before doing so.
Are the CTi LT heads vacuum-compatible?
Yes. The CTi LT pyrometer heads are vacuum-compatible.
Configuring and scaling
Select the model, optics, and cable length on this page and use Request Quote to order. Cable lengths are 3.3 ft (1 m) standard, 9.8 ft (3 m), 26.2 ft (8 m), or 49.2 ft (15 m). Contact W5 for anything the selector doesn't cover, such as optional digital interfaces, relay outputs, and the CF lens.
Scope of supply
CTi LT with the selected head cable length, a 4.9 ft (1.5 m) USB-C cable with USB-A adapter, and a quick start guide.
Get the CTi LT specified and supplied
W5 Engineering supplies Optris infrared temperature measurement products. We match the model to your temperature range, target size, and working distance, then specify the optics, cable length, and any fieldbus interface you need. Contact us with your process temperature and measurement distance and we will return a configuration recommendation and quote.
