34 BD LSR II User’s Guide
Filters
Optical filters attenuate light or help direct it to the appropriate detectors. The
BD LSR II instrument uses dichroic filters. Dichroic filters transmit light of a
specific wavelength, while reflecting other wavelengths. The name and spectral
characteristics of each filter appear on its holder.
There are three types of dichroic filters:
• Shortpass (SP) filters transmit wavelengths that are shorter than the
specified value.
• Longpass (LP) filters transmit wavelengths that are longer than the
specified value.
• Bandpass (BP) filters pass a narrow spectral band of light by combining the
characteristics of shortpass filters, longpass filters, and absorbing layers.
Discriminating filters (DF) and ALPHA™ filters (AF) are types of bandpass
filters.
When dichroic filters are used as steering optics to direct different color light
signals to different detectors, they are called dichroic mirrors or beam splitters.
• Shortpass dichroic mirrors transmit shorter wavelengths of light to one
detector while reflecting longer wavelengths to a different detector.
• Longpass dichroic mirrors transmit longer wavelengths to one detector
while reflecting shorter wavelengths to a different detector.
The BD LSR II instrument octagon and trigon detector arrays use dichroic
longpass mirrors on their inner rings, and bandpass filters on their outer rings.
However, you can customize the arrays with other types of filters and mirrors.
In Figure 1-5 on page 35, the inner ring is colored gray, and the outer is blue.
LSR2.book Page 34 Tuesday, April 25, 2006 3:34 PM
To Next Page
Loading...
