Category Archives: Hardware

Optical measurements with a vertical traverse system

Meanwhile we have learned to control the motion of traverse systems. This enables us to record position dependent spectra and generate color profiles as well as thickness profiles. These give valuable information for operators controlling  large area coaters. Results are available immediately after production.

Our first system records transmittance and reflectance spectra (from both sides of large glass substrates) in the range 380 … 1000 nm. Data are recorded with Zeiss MMS1 spectrometers and tec5 electronics. 2 stabilized halogen light sources provide the required radiation.

All 3 spectra are taken simultaneously at the same sample spot. Here are some sketches of the optical setup:



The spectrometer units (including light sources and electronics) are mounted on 2 vertical rail systems (made by ITEM). The rail systems are mechanically synchronized and driven by a Trinamic stepper motor.

The measuring heads can be positioned at any location on the glass as well as several calibration positions below the glass.

The whole system fits in a container of 400 mm width and 1000 mm length. This was a requirement of our customer. The open slit in the middle provides enough space for the glass (more than 2500 mm) to move through the system:


The spectrometers as well as the stepper motor are controlled by our CODE software. CODE scripts are used to execute actions like calibration and automatic scans. Measurements can be triggered by an OPC connection – in this case CODE provides an OPC client.

Light source and measuring heads for transmission and reflection, mounted on the rail system:


System opened, showing one measuring head with electronics and the energy chain for power supply and ethernet connection:


Typical spectra of high quality:


The measured spectra show excellent agreement with those measured by a laboratory research instrument in the range 380 … 950 nm):


Coupled to our BREIN software operators get information about inhomogeneities across the pane (transmittance,reflectance, color). The display below shows a thickness vs. position for the last 3 panes:


We can provide similar solutions for horizontal scanning as well, IN addition, we can mount measuring heads for any angle of incidence in the range 8° … 60 °.

In the case of light scattering products such as textured solar glass we can provide an excellent measuring system recording R and T using an integrating sphere.



The WOSP MRC-DESKTOP system records reflectance spectra of glass panes or other flat and large samples for 30°, 45° and 60° angle of indicence.

Spectra are recorded in the wavelength range 380 … 1000 nm using halogen light sources and a Zeiss MMS 1 spectrometer. After calibration the time to acquire the required sample spectra is less than 10 seconds.

The image below shows the first demonstration prototype as presented at the ICCG 11 exhibition. The metal frame is based on ITEM parts which allow very flexible modifications of the setup, adapting the system to customer needs. All required optical parts are above the sample plane – in principle there is no size limit for samples.


Recording data requires 3 steps:

  1. Redording of the dark signal of the spectrometer. This takes about 3 seconds and does not require any action except a mouse click.
  2. Secondly, a reference mirror has to be placed at the sample position, and the signals for the 3 angles are recorded. Data acquisition takes less than 10 seconds.
  3. Finally, data are recorded for the sample which is placed on the table.

We recommend to take dark and reference spectra at least every 15 minutes.


The system is operated using our CODE-NF software which is a restricted version of our CODE thin film analysis and design software package. In CODE-NF you cannot perform automatic parameter fits – all other features of CODE are contained in CODE-NF.

CODE user interfaces are very flexible. We recommend to have a few buttons only, triggering dark, reference and sample measurements as well as the export of the obtained data.




The WOSP RT-DESKTOP spectrometer system records absolute reflectance and transmittance spectra of glass panes or other flat and shiny samples. Measurements are done in a few seconds. A wide range of angles of incidence is possible. No reference standard is needed for reflectance.

The system consists of

  • a mobile stabilized halogen light source (25 W)
  • a mobile spectrometer unit (using a Zeiss MMS1 spectrometer and tec5 electronics)
  • mechanical accessories that assist you in positioning all components.

Spectra are recorded in the range 380 … 1000 nm.

You need to provide a flat table (which is not part of the system) and electrical power. The spectrometer connects to a USB port of your computer.  Alternatively, you can use an ethernet connection.


How it works

You can move and turn both the spectrometer unit and the light source on the table, performing the following sequence of actions:

  • Pointing the field of view of the spectrometer away from the light source (to a dark surface, ideally) you record the dark spectrum, i.e. the detector signals for vanishing light intensity.
  • Then you arrange the components in a way that the full intensity (100%) is recorded.
  • From now on you can record absolute transmittance and reflectance spectra for various angles of incidence.

The image below shows a reflectance measurement taken at 45°:



You are not limited to absolute measurements – if relative measurements are more appropriate for a given problem, you are free to go this way as well.

You have plenty of time to do the measurements. The graph below shows the ‘100% line’ 5 minutes after the backgound signal has been measured:


The system is controlled by our CODE-NF software which allows to compute various technical data from measured spectra like color coordinates or integral transmittance and reflectance values. As an option you can upgrade to the full CODE software package which allows to obtain film thickness and optical constant values based on physical modelling.

In order to record high quality spectra the operators need to execute a few commands only. Both CODE-NF and CODE are very flexible concerning user interfaces. We recommend to provide large buttons for dark, reference and sample measurements. You can save measured spectra manually or  automatically to folders or a MySQL database.


The screenshot below shows (in red) the measurement of the absolute reflectance of a silicon wafer (30° angle of incidence). The blue spectrum is a model computation based on literature data of silicon with a 4 nm native SiO2 layer on top – the agreement is excellent, also for other angles of incidence:


The next graph shows a more advanced example. 6 measured spectra (absolute T and R spectra, taken at 30°, 45° and 60°) have been used to fit an optical constant model for Schott Borofloat glass.


The obtained optical constants (real part n of the refractive index, absorption coefficient alpha) are shown here: