Night Vision Device Optical Diopter: Principles and Applications

What is diopter?

Diopter (symbol: D) is a unit of measurement for the refractive power of an optical system (e.g., lenses, eyepiece lens), defined as the reciprocal of the focal length (f). The calculation formula is: D=1f (unit: meters, m). For example, a lens with a focal length of 0.5 meters has a diopter of +2D (convex lens that can focus light), while a lens with a focal length of -0.25 meters has a diopter of -4D (diverging light, concave lens).

Diopter is widely used in eyepiece adjustment of glasses, microscopes, telescopes and optoelectronic imaging equipment (such as pvs31 night vision goggles and thermal imagers) to ensure that users with different vision can clearly observe the target image.

Application of diopter in optoelectronic imaging equipment

Diopter adjustment of night vision goggles

PVS 14 night vision use image intensifier tubes (IIT) to amplify low ambient light (such as moonlight and infrared radiation) and convert them into visible images. Due to the different degrees of refractive error (such as myopia and hyperopia) among different users, night vision goggles are usually equipped with adjustable diopter rings (usually ranging from ±2D to ±5D), which change the equivalent focal length by axially moving the lens set to make the retinal image clear.

Adjustment steps:

1. Adjust the objective lens to initially focus on the target in the distance;
2. Rotate eyepiece diopter ring to compensate for user vision differences (e.g. -3D adaption for 300-degree myopia);
3. PVS 31 night vision devices require independent adjustment of the left and right eyepieces to ensure parallax balance of dual eye.

Diopter adjustment of thermal imagers

Thermal imagers use IR detectors (such as vanadium oxide microbolometers) to convert target thermal radiation into visible images. The eyepiece diopter adjustment methods include:

• Mechanical adjustment: similar to night vision goggles, changing the light path by lens displacement;
• Electronic adjustment: Some digital thermal imagers support software-level diopter compensation (such as digital increase and decrease);
• Automatic adaptation: High-end models integrated vision detection sensors, automatically optimize diopter.

The physical meaning of diopter adjustment

1. Image distance compensation: According to the lens formula, 1f=1u+1v (uu is the object distance, vv is the image distance). The essence of diopter adjustment is to adjust (v) to match the user's retinal position.
2. Diopter tolerance: The normal adjustment range of the human eye is approximately ±4D. Beyond this range, additional optical correction (such as additional lenses) is required.

Summary

Diopter is a key parameter for the optical system to adapt to human vision, and its adjustment ability directly affects the user experience of pvs14 nvg night vision devices, thermal imagers, etc. Through accurate diopter compensation, it can ensure that users with different vision can obtain clear and low-distortion observation effects, which has important application value in the military, security and medical fields.