Lambert Instruments

The LIFA -Lambert Instruments Fluorescence Attachment for lifetime imaging microscopy can be attached to any widefield fluorescence microscope and works in the frequency domain, which means that it uses a modulated light source and a modulated image intensifier as detector. The system is easy to install (within 1 hour) and to operate and does not require an optical bench with laser. The LIFA -Lambert Instruments Fluorescence Attachment system has been judged "easy and highly quantitative". And last but not least, it's reasonable priced.

Components
Light source
Typically, the LIFA -Lambert Instruments Fluorescence Attachment uses high brightness LED light sources of different wavelengths. The use of an LED has several advantages over a laser as light source: LEDs are inexpensive, can be modulated over a broad frequency range (10 - 100 MHz), have no interference effects or speckles, and are available in many wavelengths in the UV and VIS spectrum.
Additionally, a modulated laser diode or a CW laser modulated by an external modulator (Pockel cell or AOM) can also be used as light source, especially when higher intensities are needed. This is advantageous when combining the LIFA -Lambert Instruments Fluorescence Attachment with a spinning disk to obtain optical sectioning and 3D imaging.

Image intensifier
The high-resolution image intensifier is the key component of the LIFA -Lambert Instruments Fluorescence Attachment . The gain of the image intensifier can be controlled by the voltage across the MCP and is typically in the range of 100 to 10,000 times. Also the voltage between cathode and MCP can be changed in order to control the gain. During modulation, the gain is modulated via the cathode voltage.
Depending on the application, the photocathode has to be chosen that has the appropriate sensitivity per emission wavelength. For GenII we normally offer either the S20 or the SuperS25 photocathode. For higher quantum efficiency (25% instead of 10%) the GenIII intensifier is offered, with the GaAs photocathode. See here for the photocathode characteristics.

Digital CCD camera
The image intensifier is either lens-coupled or fiber-coupled to a intensified CCD camera. The fiber-optic coupled image intensifier and the CCD unit is integrated in the LI2CAM MD camera that is made by Lambert Instruments. This intensified CCD camera is very compact and has a higher gain than the lens-coupled combination as a result of the more efficient and compact fiber coupling. The lens-coupled combination allows easy detachment and exchange of camera from image intensifier by the user.

Integrated Control unit / Signal generator / Power supply
This unit supplies the RF modulation signals at controlled frequency, amplitude and phase difference to the LED light source and to the image intensifier. The unit also supplies the DC power and high voltage to LED and image intensifier. An extra output to drive an external modulator is available as well as monitor outputs to check the modulation signals.

LI FLIM software
The user-friendly software is developed by Lambert Instruments. With this package you can acquire lifetime images, process them and do statistic analyses. Users that have the password for the new release, can download the software from the LI FLIM software page directly.

LIFA set-up

Patents
Patents owned by Photonic Research Systems Ltd.