Monochromator

A monochromator separates out the single-wavelength components from an incoming light beam. The Model 03 Mini-Chrom Monochromator does this with an adjustable reflection diffraction grating; adjusting the wavelength dial turns the grating to a particular angle, allowing light of the corresponding wavelength to leave the exit slit and go to your eye or some other detector.

Digital Multimeter

Use the DMM to measure the output voltage from the photodiode/amplifier.

Power Supply

Connect this SOLA Solids power supply to the DMM and the photodiode/amplifier.

Photodiode/Amplifier

Light entering the photodiode/amplifier hits a photodiode, generating a tiny current. This current flows to the amplifier, which produces a measurable voltage signal in response. The output voltage is proportional to the light intensity hitting the photodiode when the input intensity is sufficiently small. Look at the photodiode/amplifier’s responsivity curve (pdf version).

Fiber-Optic Cable

Works by total internal reflection. Use it to transmit light in a controlled fashion from the source to the entrance slit of the monochromator.

Tube Light

A small incandescent bulb resides deep within the cylindrical metal housing. If your main task for this lab is to characterize the spectrum of an incandescent light bulb, this is your light source. It is essentially a plug-in flashlight and was built for use with spectrometer labs.

CFL

If your main task for this lab is to characterize the spectrum of a compact fluorescent light bulb, this is your light source. Basic information about how fluorescent lamps work can be found here.

Clamps

These clamps are useful for holding things steady – like the fiber-optic cable, for example.

Diffraction Grating
There are two main classes:

• Reflection
  
  The diffraction grating is outlined in red in this image of the inside of a monochromator.  Look at the second grating efficiency curve. Remember we are using Model 03.
• Transmission
  
  A Transmission Diffraction Grating

Sodium Lamp

Appears in the Summary Questions

Circuit Diagram

Look at a picture.

Background Data Collection and Analysis Summary Questions