XT2 Collimating Emission-Port Adapter0 pages

Photometrics XT2™ Datasheet
HIGH PERFORMANCE EMCCD & CCD CAMERAS FOR LIFE SCIENCES

Collimated Emission-Port Adapter
For many imaging applications, it is necessary to utilize devices such
as filter wheels and LCTFs on the emission port of a microscope. The
beam emerging from the microscope emission port, however, is coming
to a focus. Optical devices are often placed in the focusing beam,
thereby producing a series of errors, including:

Correct emission imaging with the XT2!
Filter in focusing beam

Filter in focusing beam

Parfocality

Parfocality problem!

Anytime a flat piece of glass (e.g., an emission/barrier filter) is inserted
Focusing light
in a microscope beam, the beam will no longer focus at its original
from focusing
location; instead, the location of the focal plane will be shifted. The
amount of shift will depend on the thickness of the filter as well as the
index of refraction of the glass used to make the filter. This focal-shift
New focal plane
error destroys parfocality between the detector and the eyepiece.
Original focal plane
However, when collimated light passes through an emission filter, the
focal plane is not shifted.

Bandpass Variation

Parfocality problem!
Filter in focusing beam
Focusing light
from microscope
Parfocality problem!
Focusing light
from microscope
New focal plane
Original focal plane
New focal plane
Original focal plane

Filter in focusing light

Filter in focusing light

It is a well-known fact that the bandpass of a filter varies with the
angle at which light hits it. When a filter is placed in a focusing beam,
Edge ray
the light at the edge of the beam wavelengthfilter at a different angle than
λ2
Center hits the
λ1
theCenter ray the center of the(CWL) of bandpass
light at
beam. As a result, there is a variation in
is different at edge
λ2
the center wavelength (CWL) of the filter bandpass for different parts
and center!
Edge ray
of the beam. However, when collimated light passes through a filter,
all rays strike at the same angle, eliminating bandpass shift.

Filter in focusing light
Edge ray
Center ray
Edge ray
Edge ray ray
Center

λ2
λ1
λ2
λ2
λ1
λ2

Center wavelength
(CWL) of bandpass
is different at edge
and center!
Center wavelength
(CWL) of bandpass
is different at edge
and center!

Edge ray
→ Angle of incidence changes from edge to center.

→ Angle of incidence changes from edge to center.
→ Angle of incidence changes from edge to center.

XT2

The Solution…
Filter in collimated light
No wavelength shift!
All light hits filter
at same angle.
λ1
λ1
λ1

Focusing light
from microscope

Lens systems
in XT2

PM-DS-017 Rev B3 ©2013 Photometrics. All rights reserved.

No focal shift!
Original focal
plane is preserved.

•t Two-piece optical adapter creates 1 – 4” of collimated (infinity)
Filter in collimated light
space at emission port of microscope, thus allowing addition of wavelength shift!
No
All light hits filter
other optical devices without sacrificing performance or
Filter in collimated light
at same angle.
No wavelength shift!
introducing optical aberrations
Focusing light
from microscope

•t Provides “extra space” at microscope emission
Focusing light
port for installation of instrumentation such as filter
from microscope
wheels and liquid-crystal tunable filters (LCTFs)
Lens systems
in XT2

•t Flexible enough for use with a variety of optical
Lens systems
devices with C-mounts
in XT2

λ1
All light hits filter
λ1
at same angle.
λ1
λ1
λ1
λ1
No focal shift!
Original focal
plane is preserved.
No focal shift!
Original focal
plane is preserved.