METHOD AND METHOD AND APPARATUS FOR CONTROL OF LIGHT INTENSITY FOR IMAGE ANALYSIS

An image apparatus for measuring true mass characteristics of the specimen in real time is provided with means for controlling the amount and intensity of background light so that the amount of light is held substantially constant and at a level providing reduced background and scattered light so that evaluations at different times on the same or on different image analysis apparatus of the same manufacture result in substantially identical measurements of mass. The light control for the conventional light microscope used with the image analysis apparatus includes four variables which are the light intensity of the light bulb, the size of the field iris, the size of the condenser iris, and the movement the condenser lenses in a vertical or "Z" direction for focus. Preferably, a fixed aperture means in the form of a cup attachment is secured to the condenser iris optics to provide a fixed size iris for the condenser. The controls for the variable condenser iris are opened wide so that the less size aperature in the fixed condenser iris is that which is controlling of the light passing through the condenser optics. The preferred attachment device is a cup-shaped member of one piece metal which is attached by a threaded fastener in a non-invasive manner to the bottom of the condenser iris and optics. A monitor displays the intensity of the background light as a numerical value and the intensity of the light bulb is adjusted to provide a substantially constant background light transmitted to a CCD sensor or camera.