The Optris CTi 4ML is a miniaturized high-speed infrared thermometer for temperature measurement from 32 °F to 1,112 °F (0 °C to 600 °C). With an ultra-fast exposure time of 110 µs, it is built for precise measurement in ultra-fast processes with low object temperatures starting at 32 °F (0 °C). It measures across a 2.2 to 6.0 µm spectral band, the broadest in the CTi range. The small sensing head is 0.55 in (14 mm) in diameter and 1.10 in (28 mm) long. It runs up to 158 °F (70 °C) ambient without cooling and connects by cable to a separate electronics box, which can be connected directly to a PC or smartphone.
Temperature range: 32 °F to 1,112 °F (0 °C to 600 °C)
Spectral range: 2.2 to 6.0 µm
Optical resolution: 10:1; optional CF optics give a 0.20 in (5.0 mm) spot at 2.0 in (50 mm)
Exposure time: 110 µs; response time 320 µs
Measurement uncertainty: ± (0.3% of reading + 3.6 °F / 2 °C), whichever is greater
0.55"/14 mm sensing head with 10:1 optics and optional close focus
Speed
110 µs exposure
A 110 µs exposure time and 320 µs response time, matching the fastest sensors in the CTi range but at low object temperatures.
Range
From 32 °F
Measures from 32 °F (0 °C) to 1,112 °F (600 °C) across a 2.2 to 6.0 µm band, the broadest spectral range in the CTi family.
Noise
70 mK NETD
Typical NETD of 70 mK with ± 0.29 °F (± 0.16 K) repeatability, unusually low for a sensor this fast.
What it is used for
Some of the use cases for the Optris CTi 4ML include:
Ultra-fast processes: temperature measurement where a 110 µs exposure time is needed to follow the process.
Low object temperatures: fast measurement starting at 32 °F (0 °C).
Moving or intermittent targets: objects passing the sensor on a line, where a slower sensor would average across the target and its background.
Small targets: measuring 0.20 in (5.0 mm) spots at 2.0 in (50 mm) with optional CF optics.
Tight installations: mounting the 0.55 in (14 mm) sensing head where space is limited, with the electronics box sited remotely.
Key features
Ultra-fast exposure time: 110 µs, with a 320 µs response time.
Low temperature range: measures from 32 °F (0 °C) up to 1,112 °F (600 °C).
Small sensing head: 0.55 in (14 mm) diameter and 1.10 in (28 mm) long, with an M12 × 1 thread, so it fits in tight spaces.
Head operates without cooling: up to 158 °F (70 °C) ambient.
Standard or close-focus optics: 10:1 standard focus, or optional CF optics for a 0.20 in (5.0 mm) spot at 2.0 in (50 mm).
Separate electronics box: with an LCD display showing 0.1 K resolution and programming keys.
Two analog outputs: each 0/4–20 mA, 0–5/10 V, or thermocouple K, plus an alarm output and built-in USB.
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.
Peak picker: signal processing includes peak hold, valley hold, peak picker, and averaging, plus an extended hold function with threshold and hysteresis. Peak picker is unique to this model in the CTi range.
PC or smartphone connection: configuration through Optris CompactPlus Connect software or the IRmobile app.
Why engineers pick it
Speed at low temperatures. A 110 µs exposure time with a measuring range starting at 32 °F (0 °C). The short-wavelength CTi sensors are faster still but start at 482 °F (250 °C) or above.
Low noise for a fast sensor. Typical NETD of 70 mK and repeatability of ± 0.29 °F (± 0.16 K), where the comparably fast CTi LTfast runs at 180 mK on its quickest model.
Fits almost anywhere. The 0.55 in (14 mm) sensing head runs at up to 158 °F (70 °C) ambient without cooling.
Flexible integration. Two analog outputs, built-in USB, three programmable I/O pins, and optional industrial Ethernet, fieldbus, and relay interfaces.
Frequently asked questions
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 on the CTi 4ML, transmission must be set to 0.93. This value is specific to this model: the CTi 1M, 2M, and 3M use 0.92, and the 8–14 µm sensors (LT, LTfast, LThot, LTex) use 0.78. The 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?
On the CTi 4ML the sensing head cable can be shortened by a maximum of 9.8 ft (3 m).
How can I improve the noise amplitude of the sensor?
Low temperatures can cause high noise levels. To reduce this noise, the averaging time can be increased. Beyond that, 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.
How do I exchange the sensing head?
Heads are connected and calibrated at the factory, with the Head ID already entered. Any exchange of sensing heads and electronics is possible within a given model group. Every head carries a specific Head ID, printed on the head cable and engraved on the sensing head. This calibration code must be stored in the electronics box for correct temperature measurement and sensor functionality.
Can you connect two pyrometers to the same computer?
Yes. Using CompactPlus Connect or CompactConnect, depending on which pyrometers you have, you create separate instances of the software. Two pyrometers can be connected via the USB ports. Connection over RS485 is also possible, with the first pyrometer connected to the PC through the supplied RS485-to-USB adapter.
Configuring and scaling
Select the optics and cable length on this page and use Request Quote to order. Cable lengths are 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 and relay outputs.
Scope of supply
CTi 4ML 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.
Choosing between the CTi 4ML and the CTi LTfast
Both are speed-focused sensors covering low object temperatures on the same 0.55 in (14 mm) head. The CTi 4ML is faster, at 110 µs exposure and 320 µs response against 6 to 30 ms, and much quieter at 70 mK NETD. The CTi LTfast reaches lower, from –58 °F (–50 °C) against 32 °F (0 °C), goes higher, to 1,922 °F (1,050 °C) against 1,112 °F (600 °C), offers three optical resolutions up to 25:1, and tolerates a hotter mounting location at 257 °F (125 °C) against 158 °F (70 °C). Choose the 4ML for speed and resolution within its band, the LTfast for range and installation flexibility.
Get the CTi 4ML specified and supplied
W5 Engineering supplies Optris infrared temperature measurement products. We match the sensor to your process speed, temperature range, target size, and working distance, then specify the optics, cable length, and any fieldbus interface you need. Contact us with your application details and the ambient temperature at the mounting point, and we will return a configuration recommendation and quote.
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