Design of a microscope spectrometer (400-900nm range)
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The monochromator is a Jobin Yvon H20 with a 1200 lines / mm
grating, wavelength range between 200 and 900 nm. Although the photodiode
detector used is a UV model (see detector page),
the transmission of the optics is limited below 400 nm. The polarizer is a
common photographic filter with a polarization bandwidth limited to 820
nm. Consequently, he spectrometer described here has a wavelength range
limited to 400-820 nm. The monochromator is actuated by a stepper motor
(RS components) directly controlled by a PC.
The light source is focused on the entrance slit of the monochromator and the exit slit is imaged via objective lens and 45° mirror in the plane of the microscope stage. The light from a small area at the center of the microscope stage is focused on the photodiode surface with the photo eyepiece. The signal from the diode amplifier is sent to an Escort 3145A digital multi-meter ( 1 µV resolution) connected to a computer with RS232 interface. The image below shows the layout of the spectrometer and microscope. |
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