I designed and built this near-field optical microscope- first version for Actoprobe LLC. The microscope is a combination of confocal and AFM. The measured resolution of the microscope is about 20nm. I will build more version of it in near future.

1. Tip-enhanced Near-field Optical Microscope
I designed and built this system:
A Confocal Microscope
combined with Bruker Innova
AFM working as Tip-enhanced
Near-field Optical Microscope.
This was the first version. I am
building many versions of it.
AFM resolution ~ 1nm
Confocal ~ 1.3 µm (measured)
at 1.3µm wavelength, .4NA
objective and 1AU aperture
TENOM ~ 20nm (measured)

2. System
Innova AFM
Acto-S confocal microscope

3. Acto-S Confocal Microscope
Acto-S is a confocal microscope
developed to work with any AFM
but it could be used without AFM.
In the present system it could be
used by itself to produce confocal
images using external detector
and AFM hardware - software (by
routing detector signal through
AFM hardware) or with AFM to
produce confocal images with
AFM images.
It could also be used for PL and
spectral imaging. In this system
an IR version of Acto-S was used
with 1.3µm laser.

4. TENOM
TENOM was achieved by top
illumination and collection of AU
coated Si probe-tip in contact mode.
The system could produce AFM and
near-filed images side by side in a
single scan with near filed resolution
up to 20nm.
CMOS camera W/O IR filter
3D Stage with super stability
Flexible adapter for easy slide
removal (microscope)

5. Some Results
AFM Near-field Confocal
The sample under test was a reference target for AFM
calibration: 10µm pitch with 200nm depth. Images-
512X512

6. Software-NanoDrive Innova (Bruker)

7. Software-IR Camera (by me)
I wrote this software. It is used for
IR laser spot alignment with
probe-tip for optimum near-field
enhancement.

8. Software-IR Laser Control (by me)
Alignment is very crucial for tip
enhancement. To facilitate an
easy alignment of laser spot
with tip I wrote this laser
control software which could
control the laser in CW or
pulse mode with any desired
duty cycle.

9. By: Pranav Rathi (PhD)
Scanning Laser Confocal Microscope