المدينة الطبية · مختبر الأجهزة · الجهاز 62 من 69
منظار الجلد
Dermatoscope
منظار الجلد في مختبر الأجهزة في المدينة الطبية من BMEssentia. افتحه بتقنية ثلاثية الأبعاد تفاعلية، وفكّكه قطعةً قطعة، وتعرّف إلى طريقة عمله، ثم تعلّمه على منصة BMEssentia واسأل إسنشيا عنه.
محتوى مختبر الأجهزة في هذه الصفحة باللغة الإنجليزية، كما هو داخل المدينة الطبية.
- عدد الأجزاء: 10
- عدد التكوينات في مختبر الأجهزة: 2
- يُعرف أيضًا باسم: Dermoscope
مختبر الأجهزة
Dermatoscope
A polariser on the illumination and an analyser crossed with it on the observation. 646 per cent air-to-skin reflection still forms; it is rejected because a specular reflection preserves the polarisation that made it while multiply scattered light does not.
التكوينات
نسخ الجهاز في مختبر الأجهزة.
Cross-polarised head with stand-off spacer
A polariser on the illumination and an analyser crossed with it on the observation. 646 per cent air-to-skin reflection still forms; it is rejected because a specular reflection preserves the polarisation that made it while multiply scattered light does not.
Immersion contact head with coupling fluid
A coated glass plate pressed against the skin with a fluid between them. 1035 per cent with mineral oil.
الأجزاء
قطعةً قطعة.
Rechargeable lithium-ion cell and charge contacts
7 volts nominal and 800 milliamp-hours, lying inside the grip where your hand closes on it. It is the least interesting component in the instrument and it is the one that decides which head you can work with all afternoon.
Constant-current emitter driver and brightness control
A constant-current switching driver on a board about fourteen by thirty millimetres, tucked below the cell. It holds the emitter current at whatever the brightness control asks for, regardless of what the cell voltage is doing as it discharges.
Six-emitter illumination ring
Six white emitters on an annular board, spaced sixty degrees apart on a ring of nine millimetres radius, sitting twelve millimetres above the skin plane and facing it. The ring is not a styling choice.
Ring diffuser and light-guide collar
A ring of moulded light guide with a frosted emitting face, sitting just below the emitter board and surrounding the imaging bore. It takes six point sources and turns them into six small area sources, which is what stops the field carrying six hot spots and what makes the Lambertian model a fair description of them.
Illumination polariser ring
A ring of dichroic polarising film sitting directly beneath the diffuser, covering the illumination path and nothing else. Every photon that leaves the head toward the skin has been through it; nothing on the return path has.
Stand-off spacer cone and graticule
000 millimetres off the skin, with a graticule window in its wall and a soft rim that rests on the surface. It touches the patient and it does not touch the light: the twenty-two millimetres it protects are filled with air, which means the four point six four six per cent reflection is still there.
Achromatic doublet objective, 25 mm focal length
A cemented achromatic doublet of twenty-five millimetre focal length in an anodised cell, with a four-millimetre aperture stop in front of it. It is the only imaging element in the instrument and it fixes, on its own, the magnification, the numerical aperture, the resolution and the depth of field.
Crossed analyser in the observation pupil
A small disc of polarising film, three and a half millimetres across, sitting in the observation pupil just below the objective with its transmission axis at ninety degrees to the illumination polariser. It is the second half of the crossed pair and it is where the whole cross-polarised strategy either works or does not.
Field stop and 12 mm reticle window
A blackened annular aperture just above the contact face with a twelve-millimetre clear opening and a millimetre scale engraved around it. It defines the field of view, it gives the operator a ruler in the picture, and because it sits at the front rather than inside, its diameter is the field diameter with no magnification in between.
Internal baffle stack and blackened bore
Three knife-edged annular rings inside the barrel with progressively wider throats, in a bore that is threaded and blackened. They do nothing for the image and everything for what surrounds it, by removing the light that would otherwise arrive from the wrong direction and sit over the whole field as a grey wash.