Category Archives: Geometrical Optics

TIR Prism

Demo: OP-A-TP
Pira Index: 6A 44.00

 Lab Equipment  Directions
  1.  Elec.-Opt laser and power supply – yellow (match laser color and # on each)
  2. Internal reflection prism on stand
  3. small lab stand
  4. 3 finger clamp
  5. 90 degree clamp
  1.  Set up equipment as shown.
  2. Turn on laser (in dark room).
  3. Adjust to create desired effect as shown with return beam coming out parallel to ingoing beam.
Warning: Be careful not to expose eyes to laser beam.


Two Liter Internal Reflection Stream

Demo: OP-A-TL
Pira Index: 6A 44.45

 Lab Equipment  Directions
  1.  Uniphase orange laser and power supply
  2. lab pole
  3. 3 finger clamp with 90 degree clamp
  4. 2 liter bottle with attached outlet
  5. lab jack
  6. salad bowl
  7. creamer
  1.  Fill bottle with water – add a small pinch of creamer to make water slightly cloudy.
  2. Align the bottle and laser so that the ray of light exits the bottle through the outlet.
  3. Situate salad bowl to catch the water from the bottle.
  4. Without moving the bottle, remove the small black cover from the outlet hole and loosen bottle cap. Observe the light following the water path.


Frustrated TIR

Demo: OP-A-TF
Pira Index: 6A 44.00

 Lab Equipment  Directions
  1.  He-Ne laser
  2. lab jack
  3. bungee cord (secures laser to jack)
  4. double-prism apparatus
  5. vice
  6. demo multimeter
  7. photocell
  8. 2 AB leads
  9. short lab stand
  10. 90 degree clamp
  11. 3 finger clamp
  12. plug strip
  1.  Align the laser so that the beam hits the middle of one of the faces of the prism as shown
  2. Tightening the small c-clamp 1/4 turn allows light to take the straight path. Do not overtighten.
  3. The photocell is connected to the demo meter and the voltage with the beam being deflected can be compared to the voltage when the beam goes straight through the middle.
  4. You can look through the prism at the yellow “post-it” note as you tighten and loosen the clamp. You alternately see and not see the “post-it” as the ‘window’ opens and closes.


Spherical Aberration

Demo: OP-A-SA
Pira Index: 6A 65.45

 Lab Equipment  Directions
  1.  SP 155 laser
  2. Pasco laser bench
  3. beam splitter and holder
  4. lab jack
  5. large plano-convex lens
  6. paper screen
  1.  Put the laser on the bench and the large lens on the lab jack in front of the laser. Adjust the position and height of the lab jack until the laser beam goes through the center of the lens.
  2. Set the beam splitter in its holder in front of the laser. Adjust the beam splitter until several rays hit the screen after passing through the lens.
  3. Observe what happens to the pattern when you move the screen closer and further from the lens. The rays do not all focus at the same point.


Index of Refraction on OH

Demo: OP-A-RW
Pira Index: 6A 40.00

 Lab Equipment  Directions
  1.  3 plastic rulers
  2. Plastic photocube
  3. overhead projector
  1.  Place photocube filled with water to depth d on the overhead. Slide a transparent ruler under the cube and focus the ruler sharply through the water.
  2. Lay the second ruler alongside the cube. Slowly raise that ruler until it also focuses sharply. Measure the distance h that the ruler is elevated.
  3.  d/(d-h) should equal the index of refraction of water (neglecting the small effect of the bottom of the cube).


Refraction Set

Demo: OP-A-RS
Pira Index: 6A 42.45

 Lab Equipment  Directions
  1.  Photocube container with water
  2. thick white ruler
  3. refraction cube
  1.  Place the ruler in the water and observe from various angles.
  2. Look straight into the dark hole in the cube. How many dark holes do you see? Look into the opposite cube point. How many dark holes do you see?


Raindrop Refraction

Demo: OP-A-RR
Pira Index: 6A 46.10

 Lab Equipment  Directions
  1.  Round bottomed flask filled with water
  2. Flask holder (petridish)
  3. lab jack
  4. slide projector
  5. screen (to view rainbow)
  6. specially cut box, green file folder, and manila folder
  7. lab pole
  8. small 3 finger clamp
  9. telescope clamp and wood block
  1.  Set up as shown with the box between projector and lab jack and screen supported by the 3 finger clamp just above the box. To block stray light, place the green file folder as shown and the manila folder “tented” over the top of the projector.
  2. Remove the lens from the projector. Turn off the lights in the room and turn on the projector lamp.
  3. Adjust the height of the lab jack until a slit of light goes through under the edge of the box.
  4. A rainbow should appear on the screen.


Rainbow Prism

Demo: OP-A-RP
Pira Index: 6A 46.1o

 Lab Equipment  Directions
  1.  2 60 degree prisms
  2. optical slit slide
  3. 2″ x 4″ x 6″ block (with white location marks)
  4. slide projector
  1.  Set up as shown in figure with prism #1 in place on the block.
  2. Turn on the projector and if a rainbow does not show on the screen, rotate prism #1 either to the left or right until a rainbow appears.
  3. Put prism #2 in between prism #1 and the rainbow beam. You should see again a beam of white light, if not, rotate prism #2 either to the left or right until white light shows up again.


Refracted Oxide

Demo: OP-A-RO
Pira Index: 6A 65.56

 Lab Equipment  Directions
  1.  Sheet with “Barium Oxide” printed in red and blue letters
  2. acrylic rod with stoppers on ends
  3. stoppered test tube filled with water
  1.  Look at the words through the test tube, first with it flat on the paper, then with it raised slightly above the paper. What is happening?
  2. Lay the acrylic rod on top of the paper. Look at the two words on the paper through the rod.
(BOTH words are inverted when seen through the rod and raised test tube. They act like convex lenses. ‘OXIDE’ appears to not be flipped since all leters are the same right side up or inverted.


Ray Box with Mirrors

Demo: OP-A-RM
Pira Index: 6A 20.45

 Lab Equipment  Directions
  1.  universal mirror on support box
  2. pasco ray box
  1.  Place the box with the universal mirror directly behind the ray box.
  2. Set up the ray box so that parallel light beams come from the top.
  3. Darken the room. Using the knob in back of the box turn the mirror to show the reflections from the plane mirror side, the convex side, and the concave side as shown.