Optica, OSAhttps://www.osapublishing.org/optica/abstract.cfm?uri=optica-2-11-965
Short Summary
Fluorescence Lifetime Imaging (FLI)

Fluorescence Lifetime Imaging or FLI is a well established imaging parameter which finds applications in DNA sequencing, tumor detection, fluorescence tomography and high resolution microscopy. Lifetime imaging provides a method for detection of fluorescent signal within a living tissue. This is important because the fluorescent signal functionally encodes disease related information such as immune response, cancer cell growth, presence of pathogens as well as inflammation. FLI based imaging systems available in the market cost in the range of several thousands of dollars. These systems operate in two complementary modes: time domain and frequency domain.

We demonstrate a cost-effective, blind, and calibration-free solution for fluorescence lifetime imaging (FLI), an imaging modality for detection of photosensitive markers in biological systems. The system relies on consumer time-of-flight sensing and can be implemented with both time-based and frequency-based signals. This new method of FLI offers potential flexibility for both large-scale and microscopy imaging.

Leica Microsystems

Fluorescence Lifetime Imaging System
Microsoft Kinect

~ $ 100 K

Time-of-Flight Imaging Systems

Time-of-Flight Sensors: Compute depth based on speed of light (aka SONAR with light.)

Alternatively, time-of-flight (ToF) sensors such as the Microsoft Kinect, are essentially depth/range imaging devices which are far more cost-effective and operate in real time. For this purpose, these sensors are at the heart of the entertainment industry.

Much in the same way as the FLI, ToF sensors operate also two complementary modes: time domain and frequency domain.

Our Approach: Time and Frequency Domain
   Lifetime Imaging with Time-of-Flight Sensors

ToF Imaging: Relative Phase Encodes Distance Information    
        ToF FLI: Relative Phase Encodes Lifetime Information   

Frequency Domain Time-of-Flight Based FLI

  1. (a)Amplitude and phase measurements.

  2. (b)3D profile of phase image at 40 MHz. As can be seen, the extra phase at the fluorescent sample location is attributed to the sample’s lifetime as well as its depth from the sensor. Our technique allows us to estimate both of these parameters simultaneously.

Time Domain Time-of-Flight Based FLI

  1. (a)Per-pixel time-domain measurements.

  2. (b)Corresponding measured signal phase together with the estimated phase.
    Estimating phase amounts to estimating lifetime as well as depth information.

FAQ: Frequently Asked Questions
FLI-ToF : Low-cost Lifetime Imaginghttp://fli-tof.info/

Designed and Maintained by Ayush Bhandari

Keywords: Time-of-Flight, Low-cost, Fluorescence Lifetime Imaging, FLIM, Signal Processing, Depth Imaging, Calibration-free

E14-374H, 75 Amherst Street
MIT, Cambridge 02139. MA. USA

ToF Imaging: Relative Delay Encodes Distance Information    
        ToF FLI: Fourier Phase Encodes Lifetime Information   



Christopher BARSI


Camera Culture Group, Massachusetts Institute of Technology

Commonwealth School, Boston






 Ayush Bhandari *http://www.mit.edu/~ayush/MIT/
Christopher Barsi
Ramesh Raskarhttp://web.media.mit.edu/~raskar/