MOSCOW BAUMANN STATE TECHNICAL UNIVERSITY
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AIM OF THE WORK

EQUIPMENT

   Spectrometer

   Optical behch design

   Optical resolution

   CCD-detector

   Fibre optic cable

   Collimating lens

   AVALight lamp

   SPECTROMETER CONTROL PARAMETERS

REFERENCE INFORMATION

   Spectral lines

   Argon (Ar I)

   Argon (Ar II)

   Crom (Cr I)

   Iron (Fe I)

   Hydrogen (H I)

   Mercury (Hg I)

EXPERIMENT

   Experiment scheme

   Àcquaintance with control interfaces

   Order of carrying out the work

   Stage 1

   Stage 2

   Stage 3

   Practical part
 
CCD-detector
Spectrometer Avaspec 2048FI equipped with SONY 2048 detectors based on silicon CCD arrays.

The Charged Coupled Device (CCD) detector stores the charge, dissipated as photons strike the photoactive surface. At the end of a controlled time-interval (integration time), the remaining charge is transferred to a buffer and then this signal is being transferred to the AD converter.

CCD detectors have an enormous dynamic range, only limited by the dark (thermal) current and the speed of the AD converter. Advantages for the CCD detector are many pixels (2048), high sensitivity and high speed. Main disadvantage is the lower S/N ratio.

Detector SONY2048 specification
Type CCD linear array
# Pixels, pitch 2048,14 mkm
pixel width/ height 14 x 56 mkm
Sensitivity 240 V/lx.s
Sensitivity (AvaLight-HAL, 8 um fiber) in counts per ms integration time 5000 counts/W
Peak wavelength 500 nm
Signal/Noise 250:1
Dark noise Ca. 10 counts
PNRU*(max.) ± 5%
Frequency 2 MHz


*PNRU (Photo Response Non-Uniformity) - max difference between output of pixels with uniformly illuminated, divided by average signal.

The sensitivity of a detector pixel at a certain wavelength is defined as the detector electrical output per unit of radiation energy (photons) incident to that pixel.

The relation between light energy entering the optical bench and the amount hitting a single detector pixel depends on the optical bench configuration. The efficiency curve of the grating used, the size of the input fiber or slit, the mirror performance and the use of a Detector Collection Lens are the main parameters. Cylindrical Detector Collection Lens (DCL) mounted directly on the detector array.


Detector spectral sensitivity