Advancements in Microscopy

by Noelle Weber, Laboratory Marketing Manager,
(as seen in American Laboratory magazine, November 2000.)
Figure 1
Portable, digital video microscope model DG-1

Digital technology is allowing the researcher more flexibility than ever in microscopy. Capturing images digitally has several benefits. Digital images are easy to store, index, and manage, just like other digital files. They are also portable and can be e-mailed across the laboratory or across the globe in a matter of moments. Slide storage systems, slide boxes, and slide mailers may one day be relegated to the antiques section of the laboratory or at least to a dusty old storage closet. Digital images also lend themselves easily to analysis using a variety of different software programs. For those with pack rat tendencies, results of the analysis can be saved and retained indefinitely for future reference. The neatniks in the laboratory need never know.

New handheld, portable, visual analysis tools allow the researcher to capture images in the field and bring them back to the laboratory for detailed analysis. The DG-1 (Scalar Corp., Tokyo, Japan) portable, digital video microscope, allows the user to capture up to 48 images on a 4-MB disk (Figure 1). Live video images are displayed on a 2-in. LCD screen. When the desired image is attained, the click of a button captures the 640 X 480 pixel image. The image is captured using a 1/4-in. video graphics array (VGA) progressive scanning charge-coupled display (CCD), so the video image is not in real time. The still image is stored in a JPEG format on a 4-MB PCMCIA-ATA card. Using the included PCMCIA adapter, it can then be inserted directly into a laptop computer. A separate cable and interface set is required to use the microscope with a desktop computer.

A rechargeable lithium battery provides about 1-1/2 hr of continuous use in the field. The digital video microscope comes with a 30X lens; however, magnifications of 50X, 100X, and 200X are also available. A 1X lens may be used to take a macro view of the subject for documentation before proceeding with the desired magnified aspects.

The 30X and higher magnification lenses include built-in illumination; thus, an external light source is not necessary. The 30X and 50X lens are fixed focal length. A clear shield protects the spring-loaded lens. The video microscope is placed on the sample. The focal length can then be adjusted slightly until the sample comes into focus. This is ideal for paper and textile samples, as well as skin and fingerprint analyses. The 100X and 200X lenses have adjustable focus lengths, although the clear lens shield touches the sample.

Figure 2
Plug-and-play USB microscope provides 200X magnification, connects directly to a desktop or laptop computer via USB port, and transfers data easily by e-mail with included software.

The video microscope also includes a C-mount adapter, allowing it to be used on a traditional compound or stereo microscope. The video microscope’s lens is placed on the C-mount fitting, which then attaches to the microscope’s C-mount or video adapter.

Another digital product is the plug-and-play USB microscope (Scalar Corp.) (Figure 2). Handheld and featuring interchangeable lenses, it is similar to the DG-1, but instead of having its own LCD, it connects directly to iMac (Apple Computer Corp., Cupertino, CA), iBook™ (Apple), PowerBook ® (Apple) and G4 (Apple) computers. As with the DG-1, the image sensor is a 1/4-in. progressive color 350,000 pixel CCD. Resolution is 640 X 480 pixels with a frame speed of 12.5 frames/sec, or 320 X 240 pixels with a frame speed of 30 frames/sec. Still images can be captured in either PICT or JPEG format. Video images are in MOV (QuickTime) (Apple) format.

USB connectivity and software with video e-mail features make this a convenient tool for many users. While the DG-1 is completely portable, the USB microscope is only as portable as the computer to which it is connected. The biggest drawback is that it is only available in a Macintosh-based format. However, a PC version will most likely be available soon.

Figure 3
The Pixera digital video camera

If the user requires higher resolutions than those previously discussed, a digital video camera (Pixera Corp., Los Gatos, CA) (Figure 3) offers a 1.2 million pixel, 1/3-in. CCD camera with 1260 X 960 resolution on a PC and 1280 X 1024 resolution on Macintosh® (Apple) computers. Since this is a standalone camera, it must be used in conjunction with a separate microscope or other optics. The camera will thread onto any microscope using a C-mount adapter. It supports both Windows® 95/98 or NT 4.1 (Microsoft Corp., Redmond, WA) and Macintosh Power PC platforms.

For those who are still on the analog side of the digital revolution, an inexpensive frame grabber will allow any USB-enabled computer to accept NTSC or PAL input from a video camera, VCR, or DVD player. Included software supports JPEG, TIFF, and BMP formats for still images and AVI, MPG, and ASF motion file formats.