Category Archives: Hardware

Polarizer for R and T measurements

We have added a polarizer to our desktop R and T measurement system. The same polarizer can be used for all systems recording R and T for shiny, non-scattering samples.

The desktop system records the 100% signal when detector and light source are positioned directly opposite to each other:

After this measurement you can do absolute reflectance measurements at arbitrary angles of incidence. We have generated tools to conveniently set fixed angles of incidence – here we have used 45° and 60°.

The graph below shows 4 absolute spectra of a silicon wafer (45°, 60°, s- and p-polarization). We could achieve almost perfect match of simulated spectra based on literature data of the optical constants, fitting a thickness of 6.2 nm of the native SiO2 layer on the wafer. Data acquisition for each spectrum took less than 1 second (averaging 18 spectra using an integration time of 50 ms).

WOSP-UVIS

Based on the WOSP-LEDO light source we have developed a spectrometer system that can be used to measure reflectance spectra in the wavelength range 270 … 900 nm. The light source is based on LEDs only.

2 array spectrometers (not shown in the images) are used to record the sample signal and a reference signal at the same time. This makes the results independent of light source drifts.

Samples must be positioned within a few mm distance to the sample port of the system. The measured spectra are tolerant against small sample tilts or height differences.

Spectral quality is the same as for WOSP-LEDO. The unit can be used as a light source for transmittance measurements as well.

The system requires an external power supply of 12 V DC.

WOSP-LEDO – a new UV-Vis light source based on LEDs only

Our new WOSP-LEDO light source generates a homogeneous area of light emission, covering the spectral range 270 … 900 nm. It uses LEDs only – small power, long lifetime.

You can point a collimated field of view of an array spectrometer to the center of the light source and record transmittance or reflectance spectra in lab quality, within a fraction of the time a lab instrument would need.

The following transmittance spectra (100%, 0%, Schott Borofloat glass) have been recorded in less than 1 second, with a distance of about 1 m between light source and detector:

Zooms into the 0 and 100 percent spectra show excellent spectral quality:

 

WOSP-NOLAB

Based on WOSP-SUNBLOCK, the WOSP-NOLAB system can be used in glass factories to measure solar reflectance and transmittance (300 … 2500 nm) of large pieces of glass.  Total measurement time is about 5 s.

sketch

The CODE software used for data acquisition can predict the technical performance data (color, g-value, solar R and T) of arbitrary final glazing products built with the just produced coated pane. All data (spectra, measured and predicted performance data) can be automatically exported to an external SQL database.

WOSP-MAC

Multiple angle reflectance measurements

Glass for buildings and cars may have different appearance with respect to color when the viewing angle changes. The angular dependence of color values is important for the design of glass coatings, and hence it is important to verify that the wanted color values are obtained after coating deposition.

WOSP-MAC (multiple angle color sensor) is a lab instrument that measures color values at fixed angles of incidence of 30°, 45° and 60°.
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Measurements can be performed using a very simple software interface – they take about 10 seconds.

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Results for various samples are collected in a workbook which can be exported as Excel document.

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WOSP Sunblock

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A halogen light, 16 UV-LEDs and an integrating sphere have been combined with 2 spectrometers to the WOSP Sunblock system. It measures reflectance in the range 300 … 1050 nm, with the option to extend the NIR range up to 2500 nm.

illumination and sphere

The light sources inject radiation into a sphere (76 mm diameter). The intensity at the sphere wall as well as the intensity reflected by the sample are simultaneously recorded with 2 spectrometers. Signals recorded for a reference mirror and the sample are combined to compute the final reflectance of the sample.

side view

The whole block can be mounted on a traverse or a robot arm – only electrical cables leave the system.

rack system

The rack mounted system shown above has been used to record some demonstration spectra discussed below. All spectra have been acquired in less than one second.

Since the final spectrum is based on ratios of spectra the absolute light source intensity cancels – this leads to very stable results. The spectra shown below have been recorded with a delay of more than half an hour:

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The next set of spectra show reflectance spectra of float glass with SiN layers of different thickness:

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The last demo set shows spectra of solar glass with AR coatings, applied on one side only and on both sides of the glass:set3

 

 

WOSP-ART

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Once youhave optimized the design of your coating product with respect to angular variation of color you have to check if it really performs as CODE predicts.

The prototype described in this section will do the job: You can record absolute reflectance and transmittance spectra in high quality for the range 8° to 85° of the angle of incidence. The 85° are possible only for thin samples, with thickness below 5 mm. You do not need a calibration mirror since the 100% reference measurement can be done with light source and detector facing directly opposite to each other.

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WOSP-ART consists of a light source and a detector mounted on arms which can be rotated individually. Spectra are recorded for the wavelength range 380 … 1100 nm. Extensions to the UV (down to 280 nm) and the NIR (up to 2500 nm) are possible.

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Measurements are performed using our CODE software which can export results to data files or external SQL databases.

Here is a video demonstrating the operation of WOSP-ART.

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:

WOSP_8deg_Traverse_1

WOSP_8deg_Traverse_2

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:

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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:

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

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Typical spectra of high quality:

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

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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:

WOSP_8deg_Traverse_8

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.

WOSP-MRC-DESKTOP

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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.

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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.

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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.

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