Optical incremental encoder
Renishaw QUANTiC optical incremental encoder
Incremental optical encoder on a 40 µm scale designed for quick installation and high speed, with digital or analogue output from the readhead. Suits general automation where coarser resolution is acceptable.
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What are you specifying?
Select everything you need. A motor, drive and gearbox can be specified together as one axis.
Key specifications
| Outer diameter | 52–550 mm |
|---|---|
| Ingress protection | IP40 |
| Linear speed (max) | 24 m/s |
| Resolution (finest) | 50 nm |
| Accuracy | RTLC40H-S ±5 µm/m; RTLC40-S ±15 µm/m; rotary ±4.6 to ±0.5 arc sec (RESM40) |
| Interface | RS422 digital, 1 Vpp analogue |
Summarised in our own words from Renishaw plc's published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1 · Source 2 · Source 3
Notes on this data
Readhead 35 x 13.5 x 10 mm, 9 g; operating 0 to +70 °C. SDE < ±80 nm digital (linear). Rotary up to 8,800 rpm. Analogue 20 m/s (-3 dB).
Specify Motion is not affiliated with Renishaw plc. Renishaw and QUANTiC are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Engineer support
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Our experienced engineers are on hand, ready to help with your project. Whether you need the Renishaw QUANTiC itself, help sourcing it, or a modified or custom design built around your load, speed and space, tell us what the machine has to do and we'll come back with the right option.
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Typical applications
What an optical incremental encoder is
An optical incremental encoder measures motion by shining light through or reflecting it from a disc or scale with fine graduations onto photodetectors. As the disc or scale moves, the encoder outputs two square-wave or sine-wave channels in quadrature, called A and B, plus an index pulse once per revolution or at reference marks. The counter in the drive or controller tracks position by counting edges from a home point. Optical encoders achieve very high resolution and accuracy.
When engineers choose an optical incremental encoder
Choose an optical incremental encoder for precise speed and position feedback where homing at power-up is acceptable, such as servo motors, stages and machine tools. They are widely compatible and cost effective. The trade-offs are contamination and power loss: dust, oil and condensation can obscure the optical path, and position is lost when power is removed. For harsh environments, magnetic or inductive encoders may suit better.
How to specify the Renishaw QUANTiC
Send these with your enquiry and an engineer can confirm the right QUANTiC variant or an equivalent:
- Resolution (lines per revolution or µm)
- Output type: TTL, HTL or sin/cos
- Index or reference marks
- Shaft or hollow shaft size (mm)
- Maximum speed (rpm or m/s)
- Supply voltage (V)
- Environment and IP code
Common mistakes to avoid
- Choosing resolution above what the drive input can count
- Running long cables with TTL signals without line drivers
- Ignoring contamination in open optical designs
- Forgetting homing routines after power-up
Renishaw QUANTiC: frequently asked questions
Can you help replace Renishaw QUANTiC or source the original?
Send the full model code, quantity and required date. Our engineers can check original-part availability and assess suitable alternatives, including supply-network options where appropriate. We confirm compatibility and any changes needed before recommending a replacement.
What is the Renishaw QUANTiC?
Incremental optical encoder on a 40 µm scale designed for quick installation and high speed, with digital or analogue output from the readhead. Suits general automation where coarser resolution is acceptable. Published series figures include outer diameter 52 mm, outer diameter 550 mm, linear speed 24 m/s, resolution (finest) 50 nm. It is made by Renishaw plc; Specify Motion can help source it or propose an equivalent.
Who makes the Renishaw QUANTiC?
The Renishaw QUANTiC is made by Renishaw (Renishaw plc) and is listed here for engineers comparing options. Specify Motion is not affiliated with Renishaw plc; brand names are used only to identify the product.
What is the outer diameter of the Renishaw QUANTiC?
The published series minimum outer diameter is 52 mm. Individual models and sizes in the QUANTiC range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the Renishaw QUANTiC?
We can assess suitable replacement options. Our engineers can review the original model and propose options for your load, speed and environment. An engineer confirms the fit against your application before recommending anything.
What is quadrature output on an incremental encoder?
Quadrature output provides two channels, A and B, offset by 90 electrical degrees. Comparing which leads gives direction, and counting edges on both gives four times the line count in resolution. An index pulse marks a reference position for homing.
What is the difference between TTL and HTL outputs?
TTL outputs use a 5 V differential signal, which suits high frequencies and is commonly used with line drivers. HTL outputs use a higher voltage swing, typically matched to a 10 to 30 V supply, which improves noise immunity on long cables. Match the output type to the drive or controller input.
Further reading: Absolute vs incremental encoders · How to select an encoder · Encoders and feedback
Other optical incremental encoder series
Engineer support
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