Spider: This is not a real spider. It is an electron momentum (2-D) image generated by velocity map imaging (VMI) machine. The cylindrical symmetry of the laser field enables us to do the so-called Abel Inversion on the image which gives these fine structures. The spider legs are holography images coming from quantum interference between different electron pathways and it is a unique feature of strong field ionization (SFI). Further readings: Abel Inversion; VMI; SPIDER pattern.

Owl: This is not a real owl. It is an ion momentum (2-D) image also generated by our VMI machine. The difference here is that it is the x-t projection of the full 3-D momentum. In the Spider picture, the image is x-y projection of the electrons. The time information is very hard to obtain for single electrons/ions. Thanks to the recent development of the TPX3CAM camera which has 1.56 ns timing resolution, the ion’s timing information is now avaiable. The reason why the x distribution is symmetric is because the laser is oscillating back and forth in that direction. In the meanwhile, the time dimension has a non-trivial relationship to the luminosity of the hits arriving at the detectors which results in this interesting picture of owl. Further reading: TPX3CAM+VMI; TPX3CAM.

Squid: This is not a real squid. It is a complicated fragmentation correlation plot coming from triple ionization’s fragmentation. Here a deuterated water molecule D2O was triply ionized and runs into a strong Coulomb explosion among all three atoms. By capturing all three ionic fragments’ 3-D momentum, we can rotate the whole frame to make the bisector of the two D ion along the x+ on the image. This will force both D+ to locate on the right hand side of the graph while O+ on the left hand side, forming the so-called Newton’s plot. The experiments were carried out by our collaborator Andrew Howard and his colleagues at Stanford University’s Phil Bucksbaum group. Further reading: Newton’s plot; Triple ionization of D2O.

Crab claw: This is not a real crab claw. It is a Dispersion Scan (D-Scan) result from our recent Stretched Hollow Core Fiber (SHCF) laser develpment. The x axis is Second Harmonic Generation (SHG) wavelength. Y axis is the depth of dispersion material in D-Scan. The color is reflection of spectrum intensity. For a laser pulse as short as 10fs, one would expect a Transform Limited (TL) pulse to show a horizontal line instead of having structure in the picture. But since it is hard to compress all the colors at the same time, the pulse is usually chirped in some way which leads to this “crab claw” structure. Further reading: D-Scan; SHCF.

The Milky Way: This is the milky way! Our universe! It is human’s dream! Aren’t you motivated to try out the space travel and explore the universe by yourself? Now let’s do it! It shows that we can generate the Universe in our experiments! I think it is really cool to show these structures and link to our galaxy. And I wish one day people could fly out of the Milky Way and explore the rest of the universe! Upper row: left shows D-scan at a special angle and less dispersion; right is the VMI image on the fly shown from our TPX3CAM software. Lower row: left shows the top view of our galaxy; right shows the side view of the Milky Way. The images are linked to their original sites.