Systems and methods for precision nonlinear microscopy
Systems and methods of microscopy include and/or apply a laser light source configured to produce an excitation light; a modulator configured to modulate the excitation light to produce a modulated light; a pulse compressor configured to compress a pulse of the modulated light to produce a pre-compensated light; a beam scanner configured to raster scan the pre-compensated light on a sample; a detector configured to receive a light signal from the sample and produce a detection signal; and a lock-in amplifier configured to receive the detection signal and perform an electronic heterodyne amplification of the detection signal.
1 . A microscopy system comprising:
a laser light source configured to produce an excitation light;
a pulse compressor configured to compress a pulse of the excitation light to produce a pre-compensated light;
a beam scanner configured to raster scan the pre-compensated light on a sample;
a multi-channel detector configured to receive a light signal from the sample and produce a multi-channel detection signal; and
a multi-channel lock-in amplifier configured to receive the multi-channel detection signal and perform a multi-channel electronic heterodyne amplification of the multi-channel detection signal, wherein the multi-channel lock-in amplifier includes:
an internal oscillator,
a phase lock loop (PLL) configured to lock the internal oscillator to an input clock frequency thereby to generate a reference signal,
a mixer configured to multiply the multi-channel detection signal by the reference signal, thereby to generate a multiplied signal,
a filter configured to filter the multiplied signal, thereby to generate a filtered signal,
a rectifier configured to demodulate an envelope of the filtered signal, thereby to generate a rectified signal, and
an amplifier configured to apply a gain to the rectified signal, thereby to generate an amplified signal.
2 . The system of claim 1 , further comprising a modulator configured to modulate the excitation light, wherein the modulator is an amplitude modulator or a polarization modulator.
3 . The system of claim 1 , further comprising a beam shaper configured to modify a spatial profile of the modulated light.
4 . The system of claim 1 , wherein the multi-channel detector further includes an amplifier.
5 . The system of claim 1 , wherein the multi-channel lock-in amplifier is further configured to receive a laser clock from the laser light source.
6 . The system of claim 1 , wherein the multi-channel detector is configured to receive a plurality of single channels individually and produce the multi-channel detection signal.
7 . The system of claim 1 , further comprising a control unit configured to control the modulator and the beam scanner.
8 . The system of claim 7 , wherein the control unit is configured to receive an output of the multi-channel lock-in amplifier in a digital format, and to perform an image reconstruction of the sample based on the output.
9 . The system of claim 1 , wherein the multi-channel lock-in amplifier includes a phase shifter configured to apply a phase change on the locked signal, thereby to generate the reference signal.
10 . The system of claim 1 , wherein the input clock frequency corresponds to a clock of the laser light source.
11 . The system of claim 1 , wherein the multi-channel lock-in amplifier includes an adder configured to apply an offset voltage to the amplified signal, thereby to generate an output signal.
12 . A multi-channel lock-in amplifier configured to perform multi-channel electronic heterodyne amplification, the multi-channel lock-in amplifier comprising:
a first-channel input configured to receive a first channel of a detection signal, the first channel of the detection signal corresponding to an imaging of a sample that has been irradiated with an excitation light from a laser light source;
an input reference configured to receive a first reference signal having a known frequency;
an internal oscillator;
a phase lock loop (PLL) configured to lock the internal oscillator to the input reference, thereby to generate a second reference signal;
a mixer configured to multiply the first channel of the detection signal by the second reference signal, thereby to generate a multiplied signal;
a filter configured to filter the multiplied signal, thereby to generate a filtered signal;
a rectifier configured to demodulate an envelope of the filtered signal, thereby to generate a rectified signal; and
a gain amplifier configured to apply a gain to the rectified signal, thereby to generate an amplified signal.
13 . The amplifier of claim 12 , further comprising a phase shifter between the PLL and the mixer, and configured to apply a phase change to the second reference signal.
14 . The amplifier of claim 12 , further comprising an adder configured to add a voltage offset to the amplified signal, thereby to generate an output signal.
15 . The amplifier of claim 12 , wherein the reference signal is a clock of the laser light source.
16 . The amplifier of claim 12 , further comprising:
a second-channel input configured to receive a second channel of the detection signal, the second channel of the detection signal corresponding to the imaging of the sample that has been irradiated with the excitation light, wherein a wavelength range of the second channel of the detection signal is different from a wavelength range of the first channel of the detection signal.
17 . A microscopy method, comprising:
generating, by a laser light source, an excitation light;
irradiating a sample with an imaging light, wherein the imaging light is based on the excitation light;
detecting a light signal from the sample, thereby to generate a multi-channel detection signal, wherein the light signal is responsive to irradiation of the sample with the imaging light; and
performing a multi-channel electronic heterodyne amplification of the multi-channel detection signal, thereby to generate a digital image signal, wherein the multi-channel electronic heterodyne amplification includes:
multiplying the multi-channel detection signal by a reference signal having a known frequency to generate a multiplied signal, the reference signal being based on an output from an internal oscillator,
filtering the multiplied signal to generate a filtered signal,
demodulating an envelope of the filtered signal to generate a rectified signal, and
amplifying to the rectified signal to generate an amplified signal, the digital image signal being based on the amplified signal.
18 . The method of claim 17 , further comprising reconstructing an image of the sample based on the digital image signal.
19 . The method of claim 17 , wherein the multi-channel electronic heterodyne amplification includes:
locking an internal oscillator to a clock of the laser light source to generate the reference signal.
20 . The method of claim 14 , wherein the multi-channel electronic heterodyne amplification further includes applying a voltage offset to the amplified signal to generate the digital image signal.
21 . The method of claim 17 , wherein an order of a multiphoton process of the microscopy method is resolved by locking the multi-channel detection signal to at least one frequency based on the order.
22 . The method of claim 17 , wherein coherent and incoherent signals are resolved from each other by modulating a polarization of the excitation light, and lock ed to at least one modulated frequency.