Help with Laser Based Experiment!!!!

[ProxyWorm]

I am doing the Using a Laser Pointer to Measure the Data Track Spacing on CDs but slightly changed (I'm using different colored lasers to measure the DTS to see if there is a difference) and i just cant seem to get any of my measurements right. Any of the topics I've seen of this experiment in the past got lower numbers than i did for there D for any number (i.e they got 1575 nm for d, m= +1) While i got 4090 nm for d,M= +1. I don't know what im doing wrong to get this number.If some one could give me a simpler explanation for how your suppose to measure the DTS please help because my project is going to be due soon. Thank you for any help or suggestions.

[ProxyWorm]

Can anyone please help me i don't have much time left till i have to turn in my project

[deleted-71882]

Hello ProxyWorm,

It's always hard to determine what might be going wrong when I can't see the experimental setup. Nevertheless, here are a few comments to consider.

Are you using the correct wavelength for your laser?

Are you using the correct sign for each of the angles?

CDs have different track spacings. Try the experiment with several different CDs to see what spacings you get. Try a red laser to see if you get the same spacing as with the other laser you're using.

The Science Buddies web site has a number of inquiries about this experiment. Do a search for "Laser CD" and maybe some of the discussions will help you.

Good luck, WW

[ProxyWorm]

Thank you for your helping, I think i have found the problem with my data but the only problem i have now is how do i tell whether or not one result is better than another (i.e 1348.66893 nm for Red Laser Data track spacing and 939.94785 nm for Blue Laser Data track spacing).

[deleted-71882]

ProxyWorm,

Error analysis and figuring a likely error in an experimental result is often the hardest part of the experiment.

A web search tells me that the usual spacing for a CD is about 1600 nm.

I'd suggest that you think carefully about each observation you make and what might cause an error in it. Do you get the same spacing from all the different diffraction orders? Is your angle measurement accurate? Do you have the right wavelength? Is the CD lined up exactly so that you are measuring the perpendicular track spacing? Do you get the same result if using different spots on the disk? Other issues?

I'm happy to hear you solved your earlier problem. Good luck again, WW