An Automatic Polarimeter developed by I4C-Instruments4Chem

Instruments4Chem and PicoPOL

Instruments4Chem (I4C) develops low-cost, high-performance scientific instruments. Our products are sold through the official Instruments4Chem eBay store, with eBay providing secure payment processing, buyer protection, and order management.

Here we introduce our first instrument, PicoPOL: a novel LED-based, fully automatic polarimeter designed for high-quality quantitative optical rotation measurements. Results are reported within seconds, with no user intervention required. The instrument is equally well suited to single-point optical rotation measurements and to kinetic studies where automated data logging is needed.

Although most measurements use a yellow LED source to mimic the output of the traditional sodium lamp, our instrument can also accommodate alternative LED source PCBs, providing scope for measurements at other wavelengths.

The pages on this website describe how the instrument works, examine its performance, present sample experimental results, and provide firmware/software downloads together with detailed assembly and operating instructions. A substantial amount of information has been included to help you assess whether PicoPOL may suit the needs of your laboratory. For purchasing information, please visit the Instruments4Chem eBay store.

Using PicoPOL

PicoPOL is designed to provide rapid, high-quality optical rotation measurements with minimal setup. Typical use involves inserting a sample cell, initiating a scan, and obtaining a result within seconds.
The instrument can be used in two primary modes:
  • Single-point measurements for routine optical rotation determination
  • Kinetic measurements with automated data logging
The sections below provide a quick guide to operation before moving to more detailed descriptions of instrument design and performance on other pages of this website.

What do you Receive ?

PicoPOL is supplied as a set of pre-built modules together with all mechanical components ready for setup:
  • Source module (LED + polariser)
  • Detector module (photodetector + stepper motor + analysing polariser)
  • Controller module (RPi PICO-based)
  • Laser-cut optical bench baseplate and mounting hardware
  • Stepper motor and drive system
  • Polarimeter cell
  • Cables and assembly hardware
Two configurations are available:
  • PicoPOL-OLED — standalone operation with on-board display and remote control
  • PicoPOL-PC — PC-based operation with LabVIEW interface
Setup typically takes 10–20 minutes, with no soldering required.

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PicoPOL-OLED

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PicoPOL-PC

How Does It Work ?

Plane polarised light passes through the sample and into a rotating analyser. As the analyser rotates, the detected signal follows a sinusoidal variation (Malus’s Law).

PicoPOL records a full rotation of this signal (~8000 data points), and applies curve fitting to extract the phase of the waveform.

Optical rotation is determined by comparing:
  • the phase of a blank measurement, and
  • the phase of the sample measurement
This full-curve fitting approach is robust and avoids the ambiguities often associated with manual null methods.

What Can You Measure ?

Typical applications include:
  • Optical rotation of standard solutions (e.g. sucrose)
  • Concentration determination via calibration
  • Reaction kinetics (e.g. sucrose hydrolysis)
  • Demonstrations of chirality and optical activity
The instrument supports both single measurements and time-dependent studies.

Typical Performance

With appropriate setup and warm-up:
  • Optical rotation resolution: ~0.01°
  • Typical accuracy: on the order of ±0.02°
  • Drift: typically ~0.01° per hour after stabilisation
Performance depends on factors such as:
  • optical alignment
  • temperature stability
  • LED wavelength characteristics
Extensive validation data and examples are provided elsewhere on this site.

Getting Started (Basic Workflow)


  1. Setup the instrument (10–20 minutes)
  2. Connect a 9 V DC power supply
  3. Insert a blank sample (e.g. solvent) and record baseline
  4. Insert your sample and record measurement
  5. . Optical rotation is calculated automatically
For the PC version, measurements are performed using the supplied LabVIEW interface. For the OLED version, all control is via the onboard display and remote.

Design Transparency

The PicoPOL has been designed to be both functional and understandable.
For users interested in the mechanical design, enclosure .stl files are available for download. These allow inspection of the optical bench and controller structure.
All supplied components are professionally manufactured and ready to use—no 3D printing is required.

Learn More

This site contains detailed information including:
  • Instrument architecture and design
  • Measurement methodology
  • Example data (sucrose, quartz plates, kinetics)
  • Performance evaluation and drift studies
These sections provide deeper insight into how PicoPOL works and how best to use it.

Purchasing

PicoPOL systems are available via the Instruments4Chem eBay store.
👉 [View current availability and pricing]
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