4. Spectrophotometer - Visible Type
Spectro - photometer consists of two instruments :
Spectrometer  
Photometer 
Spectrometer   for producing light of any selected color (wavelength)

5. Photometer  for measuring the intensity of light.

6. By passing Light (into sample solution) with a specific wave length
Spectrophotometer measures :
the percentage of light that is transmitted from a sample solution
the amount of light that is absorbed by the sample solution.
By passing Light (into sample solution) with a specific wave length
Sample solution inside cuvette :
placed between the Spectrometer beam and the Photometer - Detector

7. The instrument is arranged so that liquid in a cuvette can be placed between the
Spectrometer beam and the Photometer

8. There are two kinds of spectrophotometers:
Single beam spectrophotometer measures:
the light intensity of the beam before and after a test sample is inserted.
Double beam spectrophotometer :
Compares the light intensity between two light paths:
Reference sample.
Test sample.
A double beam machine makes readings easier and more stable.

10. Basic Parts of Spectrophotometer
Lamp - Light source (Tungsten Halogen Lamp)
Collimator to collect the light
Monochromator produced by :
Prism , Grating :to split white light to color of rainbow with several wavelengths
Filters to select one color with specific wavelength
Wavelength selector to select a specific color-wavelength
Cuvette  Is used to hold sample solution
Detector convert (light) photons into electrical signal (electrons)
Amplifier to amplify the electrical signal
Meter shows the data from detector (Analog Meter , Digital Display or LCD Display)
Power Switch zero control
Light Control transmittance & absorbance control

11. 1 Lamp

13. A lens to collect the light
Collimator
A lens to collect the light

14. 3 Monochromator
a Prism
to split whit light to color of rainbow with several wavelengths

17. b Diffraction Grating
to split whit light to color of rainbow with several wavelengths

20. c Filters
to select one color with specific wavelength

22. 4 Wavelength Selector

25. convert photons into electrical signal
5 Detector photocell
convert photons into electrical signal

28. 7 Meter

30. a Analog Meter

31. b Digital Display

32. C LCD Display