Fiber excitation

Excite fiber with direct beam normal incidence

ocean optics "vis 200 um" multimode

Slits full open, EMCCD 200 gain

Peaks at 455, 488, 650 nm. First two peaks easily saturate, reduced in point mode, increase with defocus. 650 peak is less flux dependent. Raster average over reduced area, signal drops with box size.

Charging present but does not seem to affect optical response.

Nothing on VPSE

Afternoon

When remounting fiber, glove catches fiber tip, fractures

Take spectra, also APD images after optimizing detector XYZ
30 um and 60um hi apertures

650 peak can see fiber core, less clear 480. Surface topography / cleave features have more effect on 480 image.

Record several images at 480 and 650 at 5 and 2 kV. Also connect PMT directly to fiber, no filter or spectrometer. Count rates to 1.8 MHz. Take several complete images no restarts.

Try using CT1 for PMT instead of CT2, now get some restarts.Back to C/T 2 runs OK.

Now take image at 1 kV for real (not 2 kV like before, one RHK mislabled 1 kV, first true 1 kV after 8 pm)