Common lighting techniques in metallographic microscopes
1. Direct illumination: Light is directed directly onto an object to obtain a clear image. This type of light is very effective when we need to obtain high contrast objects. But when we use it to shine on bright or reflective objects, it can cause mirror reflection.
2. Dark field of view: Light is projected onto the surface of an object at an angle, resulting in slanted scattered light reaching the camera, creating bright points on a dark background or field of view. With this illumination method, if there is no color difference on the surface of the object, nothing can be seen through the visual system. These two observation methods are usually equipped in a metallographic microscope.
3. Back lighting: Light that emits a uniform field of view from the back of an object, and the side profile of the object can be seen through the camera. Back lighting is often used to measure the size of an object and determine its direction.
4. Scattered lighting: Reflective lighting, providing a soft and directionless light like a dazzling shadow, which is more suitable for highly reflective objects. Due to the effect of this lighting, we compare this light to calm, directionless light on cloudy days.
5. Coaxial lighting: The formation of a uniform surface light source emitting in a vertical direction, through a semi transparent mirror at a 45 degree angle, causes the light source to illuminate the surface of an object in a vertical downward direction. This type of light source is particularly helpful for detecting highly reflective flat objects.
