PerkinElmer Spotlight 400 Series, User Manual

Page: 32 / 120

32 . Spotlight 400 Series User’s Guide
The Optical System
The imager has optics for infrared microspectroscopy and visible light. A video camera
enables you to view the sample. The two systems intersect at the aperture. When a sample
on the sample stage is in focus, its conjugate image is focused at the remote aperture.
You can choose between transmittance, reflectance or diffuse reflectance operation.
Reflectance and diffuse reflectance modes use the same optical system. This section
describes what happens within the optical system when the imaging system changes from
visible light to infrared mode in transmittance and reflectance/diffuse reflectance operation.
Dichroic mirrors form part of the optical system. The dichroic mirrors used in the imager
reflect infrared and transmit visible light.
Viewing
When you view a sample with the video camera, you are really looking at the conjugate
image of the sample, located at the remote aperture (Figure 10).
The Z-control on the joystick enables you to focus the optical image. This control moves the
sample position up and down until the conjugate image is focused at the remote aperture.
The joystick also enables you to move the position of the sample so that the area of interest
is in the center of the field of view. The automatic infrared aperture then enables you to
isolate an area of interest in Point mode. In Image mode the apertures are not needed.