Colposcope

Overview

A colposcope is a low-power stereo microscope on a stand that lets a clinician magnify and brightly light the cervix, vagina and vulva during a colposcopy, the exam done after an abnormal Pap smear or positive HPV test. Working at arm's length from the patient, it reveals surface texture and the vascular pattern of the tissue, guiding where to take a biopsy. It does not touch the patient; it is an optical and imaging instrument that hangs over the exam field.

The device is a viewing head on a counterbalanced arm on a rolling stand. The Optical Head does the magnifying and viewing; the Illumination Module lights the field and adds a vascular-contrast filter; the Focus & Support Arm positions and focuses the head; the Mobile Stand makes it mobile and height-adjustable; and the Control Electronics with the Display Panel runs the light and shows the camera image.

How it works

Light from the Illumination Module module floods the cervix coaxially with the view. Its key feature is the Green (Red-Free) Filter: swinging it in removes red wavelengths so that blood vessels, which absorb green, appear as dark lines against pale tissue. Abnormal vascular patterns are one of the main things a colposcopist looks for, along with the response of tissue to applied acetic acid and iodine.

The returning image enters the Optical Head through the Objective Lens, passes through the Magnification Changer, a detented drum of Galilean lens groups giving stepped magnification, and splits into the two Binocular Eyepiece Tubes eyepiece tubes for a stereo view. A Beam-Splitter Prism taps part of that light to the Documentation Camera, whose CMOS Image Sensor feeds the Display Panel so the procedure can be recorded and discussed.

Positioning is hands-on. The Focus & Support Arm carries the head on a counterbalance so it floats wherever it is placed, and a fine-focus knob trims sharpness on the curved cervix. The Mobile Stand rolls on braked casters and adjusts height through a Helical Gear Pair column. The Capture Footswitch in the Control Electronics lets the examiner capture images without taking a hand off the speculum or biopsy instruments.