Optical Needle / Parallax
Product Code : SCL-LAO-11216
Quick answer: The optical needle is a fine nickel-plated steel pin on a brass rod that stands in an optical bench rider or upright. Students use it as the object needle and the search needle in lens and mirror experiments, moving it until there is no parallax with an image to fix that image's position and find focal length. Lab Exports manufactures it in Delhi for schools, colleges and universities.
Specifications
| Part | Specification |
|---|---|
| Needle | Fine-pointed pin, nickel-plated steel |
| Support rod | Brass, uniform diameter |
| Mounting | Standard optical bench riders, uprights or bosshead clamps |
| Supplied with | Protective rubber tip cap; quick-start guide to parallax alignment |
How the parallax method is used
Parallax is the apparent relative movement of two objects at different distances when the observer moves the eye sideways. On an optical bench one needle serves as the object; a second needle is moved along the bench until its tip and the image of the object needle stay together as the eye moves from side to side. At that point there is no parallax, and the search needle marks the exact position of the image.
- Clamp the needle rod in a rider and set the tip at the height of the centre of the lens or mirror.
- Place the object needle at a measured distance from the lens or mirror.
- Find the inverted image by eye, then move the second needle until its tip appears to touch the tip of the image.
- Move the eye sideways and shift the search needle until the two tips move together with no separation.
- Read the image distance from the bench scale and calculate the focal length from the lens or mirror formula.
Key features
- Sharp, finely pointed tip gives a precise reference for tip-to-tip alignment.
- Nickel plating protects the steel pin against rust from repeated handling.
- Rigid brass rod keeps the needle straight and upright in the rider.
- Uniform rod diameter fits standard optical bench riders and stand clamps.
- Bright metal finish shows clearly against a dark bench or background.
- Rubber tip cap protects the point during storage.
Documentation and supply
A protective tip cap and a quick-start guide to parallax alignment are supplied with each needle. Most Lab Exports products carry a one-year manufacturer warranty.
Lab Exports manufactures the optical needle at its works in Laxmi Nagar, Delhi, and supplies it to schools, colleges and universities in India and 60+ countries, handling the export documents for each shipment. More about the company is on the About Lab Exports page.
Related Light and Optics products
- Newton's Colour Disc Model (SCL-LAO-11215)
- Magnifier Glass 3" (SCL-LAO-11225)
- Ray Optics Kit (SCL-LAO-11229)
- Convex Lens (SCL-LAO-11234)
- Concave Lens (SCL-LAO-11235)
- Concave Mirror (SCL-LAO-11236)
The full range is in the Light and Optics section of the Physics Lab range.
Frequently asked questions
How is an optical needle used to find focal length?
One needle acts as the object and a second as the search needle; the search needle is moved until there is no parallax with the image, and the object and image distances are then used in the lens or mirror formula.
Will the optical needle fit an existing optical bench?
The brass rod has a uniform diameter made for standard optical bench riders and bosshead clamps; mention the bench type in the enquiry if its uprights are non-standard.
What is the price of the optical needle?
Prices are not published on the website. Add the optical needle to the Enquiry Cart with the Add To Cart button on this page, or email [email protected] with the house code SCL-LAO-11216 and the quantity, to receive a quotation.
Does Lab Exports manufacture the optical needle?
Yes. Lab Exports manufactures the optical needle at its works at 11/315, Lalita Park, Laxmi Nagar, Delhi 110092, under house code SCL-LAO-11216.
Request a quote
Email [email protected] with the house code SCL-LAO-11216 and the quantity, or add the optical needle to the Enquiry Cart with the Add To Cart button on this page. Tender buyers can also see the Tenders and OEM page.
