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Thermo Fisher Scientific

Using the grazing angle objective (optional)

The grazing angle objective (GAO) is an optional, factory-installed addition for your microscope that allows for analysis of ultra-thin film samples on reflecting surfaces. Using the GAO is similar to using other IR objectives but differs in several ways due to its specialized design.


Because of its narrower depth of focus, you must always bring the sample into focus manually when using the GAO, and you must never use the Autofocus feature.


The grazing angle objective is very tight, so the mirror head needs to be closer to the sample than normal. This lack of space is correct and expected, but brings a risk of scraping the sample while moving the stage. Be careful not to bump the objective onto the sample during collection.


You do not need to use the illuminator when working the GAO. The extra light is not necessary and the cable might get tangled with the objective during rotation.

Collecting data with the GAO:

1. Load a sample. In the Dashboard, set Analyze Using to Reflection.

2. Prepare your measurement settings.

Before selecting Start Session or going into microscope view, start the session as normal but skip the Autofocus step at all points and focus manually. Never use Autofocus while using the GAO.

3. Capture a mosaic.

Start your session as normal. Collect a 4x mosaic, then a 15x mosaic if needed. 

4. In the toolbar, select Change objective to switch over to the grazing angle objective. 

5. Change the GAO focus. With the software or the optional Joystick, use fine movements to adjust the stage height.

  • Open the Camera View and select the Live Spectra tab under View Tools.

Camera view live spectra.png

  • Use the IR signal to determine when the sample is in focus.

6. Measure a background spectrum.

7. Analyze areas, lines, and points.

Collect your sample as usual.


Be careful not to bump the objective onto the sample during the measurement. Sampling large areas or point that are particularly far apart increases this risk.

When you finish a session, the objective automatically switches to the 4x objective. To avoid the risk of collision between the objective and the sample during rotation, move the stage down before ending the session.

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