DRAFT_Specifications_FLIM.pdf

DRAFT Fluorescence Lifetime Imaging Confocal Microscope (FLIM) Specifications

The Naval Research Laboratory has a requirement for a Fluorescence Lifetime Imaging Confocal Microscope to enable time-resolved measurements of luminescent emission spectra upon photoexcitation to determine the lifetime of emitting states with single photon sensitivity and < 15 ps temporal resolution. The system shall be capable of performing lifetime measurements / lifetime mapping of wavelength resolved luminescent emission features from monolayer transition metal dichalcogenides such as MoS2, and performing antibunching measurements on single photon emitters in monolayer WSe2 with diffraction limited spatial resolution. The system shall include capabilities for wavelength selection by both tunable bandpass filters at selected wavelengths, and gratings over a continuous range, at the choice of the user, over a range of 500-950 nm, and include three pulsed laser excitation sources. The system shall further be capable of interfacing with a commercially available closed cycle optical cryostat.

The system shall consist of the following components or subsystems:

1) a confocal optical microscope column to provide diffraction limited spatial resolution;

2) a set of pulsed laser diodes with discrete wavelengths for sample excitation;

3) a stage for time resolved photoluminescence (TRPL) measurement using free space optics and a wavelength tunable narrow bandpass filter with < 15ps time resolution;

4) a stage for single photon antibunching measurement using free space optics, a wavelength tunable narrow bandpass filter and the Hanbury-Brown-Twiss geometry with < 50ps time resolution;

5) a stage consisting of a double grating spectrometer for high resolution PL survey scans and time-resolved PL with < 15ps time resolution;

6) time-correlated single photon counting electronics, all electronics and power supplies, and control and analysis software necessary to operate system as an integrated unit from a single graphical user interface.

I. Confocal Optical Microscope

• Research grade microscope column to view sample with either binocular eyepiece or CCD camera, provide laser excitation to sample, and collect / transmit sample luminescence to detector system with free space optics and diffraction limited spatial resolution

• Polarization preserving optical path to sample and detectors

• Interchangeable objective lenses to include 20x, 40x and 100x

• Manual sample positioning stage with 1” by 1” range and 1 um resolution

• Scanned objective lens for sample imaging / scanning in the sample plane (xy) o Scan range 80x80 microns o Scan resolution 1nm o Interfaced to data acquisition software for automated scanning and intensity / lifetime mapping in the xy plane

• Capable of interfacing with commercially available closed cycle optical cryostat o Example cryostat: Montana Instruments Cryostation

II. Pulsed diode lasers and power supplies for optical excitation of sample

• Set of pulsed diode lasers in an integrated unit providing software selection of wavelength and power

• Laser driver / power supply providing temperature stabilized operation and control in both pulsed and cw modes

• Wavelengths to include 532 ± 1 nm, 640 ± 10 nm, 730 ± 10 nm

• Each wavelength includes clean-up filter, collimator, dichroic filter and bandpass filters

• Pulse width < 100 ps

• Rep rate of 40-80 MHz

• Minimum average pulsed power of at least 2 mW, CW power of at least 10 mW

• Polarization preserving optical path to sample

• Software selectable linear / circular polarization

• Software selectable neutral density filters

III. Stage for TRPL with free space optics and tunable narrow bandpass filter

• Capable of less than 15 ps time resolution after deconvolution with instrument response function (IRF)

• Spectral analysis shall be performed with a narrow bandpass filter centered at 750 nm, with center wavelength and bandpass controlled by software specific for this filter o Bandpass selectable from 3 to 12 nm o Center wavelength selectable from 700 ± 10 nm to 800 ±10 nm o Transmission not less than 50% o Clear aperture of 10 mm or larger

• Photodetector shall have the following characteristics o Spectral range 400-900nm o Quantum efficiency >40% at 600nm, 25% at 700nm, 10% at 800nm o Response time < 50 ps

• All control and analysis software to record, analyze and present lifetime data, including dynamic deconvolution of IRF

• Stage must provide at least one unused free space exit port

IV. Stage for Single photon antibunching with free space optics

• Utilize Hanbury-Brown-Twiss (HBT) methodology

• Utilize time correlated single photon counting technology

• Capable of 50 ps or less time resolution after deconvolution with instrument response function (IRF)

• Stage must provide at least one unused free space exit port

• Spectral analysis shall be performed with a narrow bandpass filter centered at 750 nm, with center wavelength and bandpass controlled by software specific for this filter o Bandpass selectable from 3 to 12 nm o Center wavelength selectable from 700 ± 10 nm to 800 ±10 nm o Transmission not less than 50% o Clear aperture of 10 mm or larger

• Photodetector shall have the following characteristics o Spectral range 400-950nm o Quantum efficiency >65% at 600nm, 60% at 800nm, and 20% at 950nm o Response time < 250 ps

• All control and analysis software to record, analyze and present antibunching data, including dynamic deconvolution of IRF o Analyze and graphically present second order autocorrelation function g2(t), extract lifetime and g2(0) for CW laser excitation o Analyze and graphically present intensity correlation data to determine for pulsed laser excitation to extract g2(0)

V. Stage for High resolution PL survey and time resolved photoluminescence analysis

• Provides wavelength analysis of steady state emission for survey scans over a wide wavelength range of 400-900 nm

• Provides time resolved analysis of emission lifetime at a user specified wavelength

• This stage can be fiber coupled to the light collecting optics

• Spectral analysis shall be performed with a double grating spectrometer operating in two selectable modes: additive and subtractive o Includes at least two user selectable grating pairs, providing spectral dispersions from 1.4 nm/mm to 4.5 nm/mm o Grating pair selection and slit widths are software controlled

• Stage shall include two internally cooled software selectable photodetectors optimized for different wavelength ranges and temporal response times o Detector 1: 400-800 nm with quantum efficiency (QE) > 10% at 500 nm and response time of 50 ps or less, providing effective temporal resolution of < 15 ps after deconvolution of IRF o Detector 2: 400-900 nm with QE > 10% at 800 nm and response time of 200 ps or less, providing effective temporal resolution of < 50 ps

• All control and analysis software to record, analyze and present PL survey scan and time resolved data, including dynamic deconvolution of IRF o Analyze and graphically present PL survey scan data o Analyze and graphically present time resolved emission data and lifetimes

VI. Software, electronics, time correlated single photon counting control

• time-correlated single photon counting electronics with time resolution of 1ps

• independently operate all detectors listed without mechanically reconfiguring electrical connections,

• all electronics and power supplies for lasers and other system components

• control computer and monitor at least 32” diagonal or greater

• control and analysis software necessary to operate system as an integrated unit from a single graphical user interface o control of all data acquisition parameters o analysis of data including fitting and extraction of lifetimes

OPTIONAL ITEMS

Please quote the following as optional line items

1. addition pulsed lasers, minimum average pulsed power of at least 2 mW, CW power of at least 10 mW, pulse width < 80ps, at wavelengths of

a) 594 nm

b) 705 nm