How to measure grating constant with digital camera

Experiment G2 grating diffraction method is used to measure grating constant.

Experimental purposes:

1, master the basic knowledge and photography skills of digital photography.

2. Using digital image processing method to measure grating constant. Experimental instruments:

Grating, He-Ne laser, slide rail, polarizer, light screen, drawing paper, white paper, adjustable bracket, digital camera Canon PowerShot A630/640, tripod, computer (built-in Photoshop, drawing and other software). Experimental principle: (read the experimental textbook p 165~ 167 and answer the exercises)

sin/mm 1kdn？ , ? ,,,

2 10k. Experimental content: 1. Optical path layout.

(1) Be familiar with the experimental instruments and devices, and call up the diffraction image of the laser passing through the grating, with the coating surface of the grating facing the light screen. (2) Adjust the distance between the grating and the screen to make the distance as large as possible, and at the same time, the diffraction spot of 1 order can be observed.

(3) Adjust the laser to be parallel to optical bench, and the grating plane and light screen to be perpendicular to optical bench. At this time, the distance from the diffraction spot of 1 order to the central bright spot is equal. Step 2 take pictures

(1) Install the digital camera on the tripod and connect the power adapter. (2) Delete all existing images in the camera. (Set the mode switch to play, press the menu key, then press the down arrow to select Delete All, and then press FUNC. /SET to confirm, right-click to select OK, and then press FUNC. /Set it again to confirm. )

(3) Turn the mode dial to position P; Set the ISO value of the sensitivity to the lowest, and set the driving mode to self-timer; Turn off the flash ().

(4) Adjust the focal length of the tripod and the lens so that the camera is flush with the diffraction spot, and the shooting picture is slightly wider than the 1 order diffraction spot spacing. In order to reduce the distortion of lens imaging, it is best to use medium focal length shooting.

(5) Half-press the shutter to complete focusing, and fully press the shutter to take pictures. 3. Measurement data

(1) Measure the distance between the grating and the light screen L: Please use one eye to observe which scale the grating (light screen) plane is vertically aligned with.

(2) Measuring the distance d of 1 order diffraction spot: open the photo just taken with Photoshop, press and hold the pipette tool to turn it into a measuring tool, measure the distance of centimeters on the coordinate paper near the diffraction spot with the measuring tool, then measure the distance of 1 order diffraction spot, and get the real distance d of the spot through proportional conversion.

(3) Change the focal length of the lens, take photos again, and measure the next set of data.